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Username Post: Poor start, Idle surge, cold or hot, code 33, 34, 44????        (Topic#222059)
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-21-09 08:44 PM - Post#1739606    

Hello all, great forum, just found it and joined!

I have an 89' 1500 P/U 5.7 TBI with some strange issues...

SYMPTOMS:
Cold or hot starts, will fire right up, will rev RPM's up like a normal start but dies right away. It will turn over about 2-5 times this way and then will fire up and run but idle surges from fairly high to REALLY low and almost dies. It will cycle like this for about 20-30 seconds and then levels off and idles OK.

Result #1

Then when I go to drive sometimes (not always) has a lack of power. During acceleration very doggy, then once on freeway runs ok, but not great. Still lacking full power. If I try to run WOT it really bogs bad. At low speeds during acceleration I have to "baby" the throttle. Sometimes (again not always) the chk eng light comes on while on the freeway but will turn back off once off the freeway and back on side streets. Then if I shut the engine down and it sits for more than 10 mins it will be difficult to start and does the whole cycle over again.

Results #2

Once the engine starts and idle settles down I drive away and all is fine. Plenty of power, no bogging, no chk eng light. Then if I shut the engine down and it sits for more than 10 mins it will be difficult to start and does the whole cycle over again. If it was running good and I shut the engine off for only like 5 mins, it will start right back up and run fine???

Diagnostics performed:

Ran codes. Came back with:

32 (EGR open command did not change MAP sensor signal. Normal EGR flow should cause slight decrease in manifold vacuum which would change MAP sensor signal)

33 (MAP sensor signal voltage was too high (low vacuum) for 5 seconds when throttle opening was under 4%)

44 (Oxygen sensor voltage was under 0.2 volts for 50 seconds of closed loop operation.)
(Lean Exhaust Indicated)


First off I have replaced cap, rotor, plugs recently. It was just part of a tune up. This was before all this started though. At first it would only have trouble starting when warm. (I know CTS right, well ran Ohm resistance tests and all ok. Plus now it will do the same thing weather cold OR hot)

Replaced all vacuum lines except pvc, what ever the other one is coming out of the other valve cover gasket and runs into the riser/spacer between the TBI and air cleaner, and the one going to the fuel charcoal canister thing. Checked vacuum levels at multiple point and all at 20 at idle.

Cycled the EGR cold (felt fine, moved smoothly) and cycled while running and engine wanted to die when I depressed it. Egr definitely working to some degree.

Checked voltage at the MAP sensor. Pulled vacuum and saw voltage change. All good there too.

Both injectors are spraying even and misting well.

Checked timing, looked ok, but not 100% sure. The mark on the balancer was kind of hard to see. I will have to get a better look later, but sometimes it runs fine so timing seems kind of out of the question??

Tried sea foam "fogging" all the vacuum lines as well. No change.

Looked over all wires and connections. All look good.

Just flashed the codes tonight and going to make sure the same ones pop again after replacing all the vacuum lines and messing around with everything under there tonight.

At a loss, I usually figure stuff out after reading a bit and doing some testing but this one has me stumped. Sorry for the flood of info but I wanted to cover as much as could remember. I have been pissing around with this for weeks now and it is getting worse and worse. I am not the DIY who buys stuff till it's fixed. I am on a tight budget and I like to diagnose things as best as possible before just throwing money at it. I have read too many posts where people replace just about everything under the hood and then find out it was something silly that could have been figured out with a little trouble shooting. Again really great site and thanks ahead of time for all of everyones time and suggestions!!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
The_Hunter 
Contributor
Posts: 983
The_Hunter
Loc: Manitoba, Canada
Reg: 02-14-05
07-22-09 06:00 AM - Post#1739748    
    In response to d8nk

Check your fuel pressure. It's a bit of a pain on TBI's, most guys t in by the fuel filter. While your doing the test might as well replace the fuel filter.
86 C10 Short Box

Computers are like air conditioners - They can't do their job properly if you open windows.


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 07:59 AM - Post#1739823    
    In response to The_Hunter

I left for work today and it was running the worst it ever has. I had a spare fuel filter on the shelf at home so I turned around and went home, threw that in just by chance... Well it ran better, but not fixed. I had my fuel pressure gauge out and ready to check it out while I was down there but, wait, they are hard lines...grrr. I have to go read the FAQ now on the best option for tapping in.

Ohh yeah, on the way in it still popped a CE light. Got to work and checked it. 44... So no more EGR and MAP error but running lean. Gotta check pressure tonight hopefully. Thanks for your input!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-22-09 08:12 AM - Post#1739833    
    In response to d8nk

Easy to T in the gauge on a TBI - once you fight the filter off.

I have the typical fuel pressure gauge kit that is available everywhere, and says "not for GM TBI" on the package. I added a couple scraps of 3/8" fuel injection hose, about 4" or so each. Clamp them over the T that comes with the kit, then shove them onto the truck's hard lines in place of the filter, then clamp those too.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 09:40 AM - Post#1739879    
    In response to someotherguy

So you recommend testing pressure with vehicle running and no filter in place? I would have some concern with junk (especially after removing fuel lines and possibly knocking crud loose) entering the injectors. Should I not worry about that...
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 01:29 PM - Post#1739978    
    In response to d8nk

After reading and reading and reading some more, I have doubts in my diagnostics. It sounds like even though I read what seemed like proper ohm's off the CTS, maybe it is off. I am going to try comparing it to a temp gun tonight.
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-22-09 01:44 PM - Post#1739986    
    In response to d8nk

The only possible crud is going to be in the tank; I've never feared running a fuel pressure test this way unless I know for a fact there's a tank full of debris.

If you're really concerned, a little more hose and a clamp-in style filter would be fine for very brief use for running the test; the TBI pump (other than 1994-1995 big block) makes a max of 14psi.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
Billy_Bob 
Contributor
Posts: 290

Reg: 05-25-09
07-22-09 02:11 PM - Post#1740006    
    In response to someotherguy

Actually I bought a new lawnmower a few years ago and did not realize it did not come with a fuel filter. It actually ran for a couple of years before I had to clean out the carburetor (and install a fuel filter!)


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 02:44 PM - Post#1740022    
    In response to Billy_Bob

Thanks guys, I will be doing some more testing tonight and will get back with new info!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 04:56 PM - Post#1740097    
    In response to d8nk

CTS @ 260 ohm @ 180 deg. No go there...

Just now when I went to start it after driving home from work and letting it sit for about 45 min it did not even want to start. Next, onto fuel pressure chk. Will be back soon...
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-22-09 05:43 PM - Post#1740130    
    In response to d8nk

Once you do the pressure test - a low result doesn't necessarily mean a bad pump. On an '89, you're old enough that a few other things could have happened. Namely, the fuel pressure regulator spring inside the TBI unit breaking, or much more common - a split/crack/pinhole in the short section of hose that attaches the pump to the hard line on the sending unit. Often these can build enough pressure to start intermittently, or will start consistently but with long crank times.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 07:07 PM - Post#1740183    
    In response to someotherguy

Ok here is the latest.

I re-tested the CTS and it was good. 260 ohms @ 180 deg.

Then I wrestled the fuel pressure out of er'. What a pain that was for me, got covered in gas... Anyways the pressure read about 6 when just cycling the ignition but stayed solid at about 9-10 when running. So that looks good.

Next I wanted to double check the timing. I found the brown wire and dis-connected it. It read 2 deg BTDC. Then I plugged the computer back in and **WOW** it now read at least double the max distance on the gauge. The last mark I have is 12 deg BTDC so it has to be at least 20-25 deg BTDC!!! That seems REALLY retarded to me. Is that norm?? What would be causing that??
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-22-09 07:14 PM - Post#1740186    
    In response to d8nk

Another ? What happens if you run the engine wihtout that wire hooked up? I know without computer controlled advancement it would most likely run poor but 20-25 deg BTDC would be worse than no advancement wouldn't it??
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
The_Hunter 
Contributor
Posts: 983
The_Hunter
Loc: Manitoba, Canada
Reg: 02-14-05
07-22-09 09:09 PM - Post#1740264    
    In response to d8nk

IMHO your fuel pressue is to low. 13psi is the ideal reading. I should have mentioned before to pinch the fuel line (where ever possible) after your pressure gauge, to see if the pump is capable of producing at least 13psi.

If it can't get the pressure above 12, your pump is shot, or possibly not getting enough power? Code 54?
If the pressure pops up to 13+ psi your pump is good, and this means you have a pressure regulator problem, described by someotherguy above.

I think you've found the source of you lean condition, percentage wise 9 psi is 30% below the required/ideal amount. This is, no doubt, beyond the limit the ECM will allow O2 closed loop compensation. Also stab the throttle and look for pressure drops, it should be rock solid. If you can, take it for a little drive, looking for pressure drops.

Just my 2 cents.

And the 6 psi initial reading is no good.
86 C10 Short Box

Computers are like air conditioners - They can't do their job properly if you open windows.


Edited by The_Hunter on 07-22-09 09:18 PM. Reason for edit: No reason given.

 
The_Hunter 
Contributor
Posts: 983
The_Hunter
Loc: Manitoba, Canada
Reg: 02-14-05
07-22-09 09:16 PM - Post#1740269    
    In response to The_Hunter

You will lose major performance with the wire disconnected. There will only we a default advancement curve that's rpm based in the ignition module. Won't hurt anything to disconnect it and play around with it, although you could overheat the manifolds/headers?
86 C10 Short Box

Computers are like air conditioners - They can't do their job properly if you open windows.


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-23-09 06:54 AM - Post#1740380    
    In response to The_Hunter

On the timing thing, I did a bunch or research on timing advance and I don't think that my reading are abnormal at all.

As far as the fuel pressure, I read in here (FAQ I think) that between something like 9-13 is ok. But if you think that is low I will research further. Also I was seeing pressure loss after the pump turned off too, but I just assumed it was a small leak in my hook up for testing. It didn't see any leaks in my connections but the smallest of leak would allow a pressure loss wouldn't it? Perhaps it is that soft line connection off the sending unit...

Also, why would my truck run perfectly fine sometimes if the fuel pressure is an issue? Like yesterday during my lunch break I drove around and made two stops and the truck ran almost perfect. Can a pump fluctuate from bad to good? If I had a cracked line off the sending unit wouldn't it be bad all the time as well??

What is weird is how much my problems fluctuate, and how it seams to be consistently worse in the mornings now. And like I said before, if it running ok and I shut it off then start it within 5 minutes it will run just fine, it only runs poor after running good if it sits for like 10 mins or so??

BTW, truck started rough this morning, let it idle for about 10 min and then drove in with plenty of power, ran great. If I let it sit and idle on it's own for like 10 minutes or so, it always seems to run good. Like it has to "warm up". But when the engine is warm and it had sat for more than 10 min (if I were to just try to drive away it would run really bad) an then I let it idle for extended periods it seems to "fix" whatever the issue is??

Sorry for the long replies, I just want to try and give as much info as I can and again thanks for the input!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-23-09 06:55 AM - Post#1740381    
    In response to d8nk

Oh yeah, no code 54. Since I flashed my codes a couple days ago, I have only had the CEL come on once and left a 44 Lean code.
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-23-09 07:45 AM - Post#1740402    
    In response to d8nk

The suggested range is 9 to 13 psi but many here feel that 9 is insufficient. I'd hate to tell you to just go ahead and replace your pump and have that not be the solution, but the somewhat low pressure reading combined with the lean code and drivability issue is *kind of* pointing to it.

You seem to be content to test things though and not frustrated with it yet so you might want to press on and try different things as they come up instead of rushing into a part replacement just yet. By now, plenty of people would have thrown hundreds of dollars of parts at a problem and not fixed it.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-23-09 08:10 PM - Post#1740782    
    In response to someotherguy

  • someotherguy Said:

You seem to be content to test things though and not frustrated with it yet so you might want to press on and try different things as they come up instead of rushing into a part replacement just yet. By now, plenty of people would have thrown hundreds of dollars of parts at a problem and not fixed it.

Richard



Losing patience after tonight... Starting to wish I had money to throw around...

I removed half the bolts on the bed and loosened the other half and jacked up the bed to gain a little more access to the pump. What a B**ch that was... Anyways got under there and cleaned up and re-did the ground. Voltage all good. I was contemplating taking the pump out so i could check on that line you keep talking about in there. After inspecting the hard fixed lines coming out of the unit, I decided not to go there. I almost guarantee that if I even attempt to crack those lines they are going to break and i will have to replace the pump no matter what...

So here is what I keep going back to in my head. If the truck runs great (as it did for my drive home from work today)sometimes, how could it be fuel pressure/volume?? If there were a hole/crack in that hose it would have to bad all the time, right??

About the only thing consistent with this whole thing is that it doesn't like to start/idle cold AND it doesn't like to start/idle warm after sitting for more than 10 minutes. WHAT CAN THAT BE??



Even though I have good readings off the CTS, would it cause poor running conditions at start-up cold and hot? My gut is saying that might be it...
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-23-09 08:19 PM - Post#1740784    
    In response to d8nk

Keep in mind it has to operate throughout a range of conditions, just because it read correct at the warmed-up temperature does not mean it is reading correctly at others.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-23-09 08:56 PM - Post#1740809    
    In response to d8nk

Good point I will check the reading in the morning when she's cold.

  • d8nk Said:


So here is what I keep going back to in my head. If the truck runs great (as it did for my drive home from work today)sometimes, how could it be fuel pressure/volume?? If there were a hole/crack in that hose it would have to bad all the time, right??




What do you think about this?
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-24-09 07:20 PM - Post#1741346    
    In response to d8nk

I forgot to check the CTS until it was too late (truck was already running for a couple of minutes) this morning. Will try to remember tomorrow morning. (It's tough to think in the morning)

Richard, what do you think about my question above?

Anyone else have ideas/comments? Really running out of ideas.

I remember reading somewhere about hooking up some cable (adhl?) to the computer and running some software hooked to a laptop to get reports generated telling what exactly the computer is doing and what readings it is getting off the sensors. Is this something I can do with my truck? What would you all recommend for that if it is possible? (ie. Where to buy cable, what software, where to download etc)

More help would be GREATLY appreciated and I sincerely thank you guys for what help you have generously given so far!!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
someotherguy 
Moderator
Posts: 25155
someotherguy
Age: 43
Loc: Texas
Reg: 08-01-03
07-24-09 07:32 PM - Post#1741359    
    In response to d8nk

I'd say it's hard to second-guess how some faults are going to present themselves. A lot of times you get something that fails only when certain conditions are met.

Generally when there's a problem with the CTS or its circuit, it reads cold, because of its design that higher resistance = colder temperature. Note the recent thread from fritz about how his was running rich/flooding; this is the typical result of CTS problems. I just wanted you to check it to see if it might point to at least some of your symptoms.

The lean code and your somewhat low pressure reading is what has me thinking it's a fuel pressure issue. You're in kind of the opposite situation of the CTS going bad and over-fueling. It's very unlikely it has failed the opposite direction and is commanding too lean of a mixture.

Just out of curiosity, have you checked and cleaned your sensor grounds - the two pairs of grounds attached at, and near, the thermostat housing? Also, ground braid from the rear of the passenger head attached at the firewall by the heater core connections, and continues on to the frame?

Have you 100% confirmed your vacuum line routings, especially where the EGR solenoid goes to the EGR valve? Those two ports on the back of the solenoid - barbed one feeds the EGR, non-barbed one is open (vent.) Rubber boot on the back of the TBI for the feed to the MAP sensor fits snug? Back to the EGR for a second, have you tested its operation with a vacuum pump? Moving it by hand only proved the passage wasn't carboned up, doesn't mean the diaphragm is good.

If you can systematically knock out all these question marks it'll help lead to the solution.

As far as datalogging, never done it, the few times I've had really persistent problems I've had a friend with a high-end scanner watch it while I drove around to repeat the problem. There are those here that have done it so maybe they'll chime in. Or, you could search the forum, and google, for WinALDL which is the program's name.

Richard
94 C2500LD / 94 C1500 / 06 300C SRT8
Check out my truck shop projects


 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2922

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
07-24-09 07:50 PM - Post#1741369    
    In response to The_Hunter

  • The_Hunter Said:
Check your fuel pressure. It's a bit of a pain on TBI's, most guys t in by the fuel filter. While your doing the test might as well replace the fuel filter.



I agree, test the fuel pressure.

Often the computer will do a good job of compensating for low pressure and the symptoms will not be the same as an old carbureted vehicle.

I know a guy who had a hard starting 4.3 in an Astro van and struggled with it for over a year. I found out he was testing his fuel pressure by putting a gauge on the end of the fuel line. I told him he MUST “T” in a gauge to test it with the engine running, and when he did, he said it showed less then a pound of pressure. The fuel pressure regulator spring was rusted and broken into 4 pieces. After he put a new regulator in it he said it did have better performance but the only symptom it had with the broken spring was a hard start at times. Not all the time.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
Billy_Bob 
Contributor
Posts: 290

Reg: 05-25-09
07-24-09 08:29 PM - Post#1741388    
    In response to d8nk

WinALDL
http://winaldl.joby.se

 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-24-09 09:52 PM - Post#1741416    
    In response to Chevytech

  • Chevytech Said:


I agree, test the fuel pressure.




I did "t" in and I got 9-10psi and I know some people say that is insufficient, but I am really having a hard time believing that is the case. The truck almost always "starts" right away. But it revs up and dies for a couple of cycles, then will surge idle for 10 seconds so. Once she is warmed up a bit and running, she runs great with no problems. If I try to just drive away without letting it do it's thing (especially when it's cold) it WILL run poor. See below for more on this...

  • someotherguy Said:

Just out of curiosity, have you checked and cleaned your sensor grounds...

Have you 100% confirmed your vacuum line routings...

Back to the EGR for a second, have you tested its operation with a vacuum pump? Moving it by hand only proved the passage wasn't carboned up, doesn't mean the diaphragm is good.

Richard



I did not see the ground behind the head, will check that.

Vacuum lines all replaced. All snug. All in correct placing. Good suggestion though, I have checked that like three times just hoping... I did not try pulling vacuum on the EGR though! I will have to try that for sure.

Also, is there a good way to inspect the pressure regulator? That is the contraption mounted right behind the injectors on the TB where the fuel lines come in right?

HOW TO DRIVE MY TRUCK:

Now I have kind of "figured out" how to drive it. It is at least getting me by.

WHEN IT"S COLD: in the morning I have to let it warm up. (on it's own BTW, if I try to "throttle it" to warm it up it will most definitely run like crap. If I try driving away "cold" that is when i get the CEL to come on the freeway) Once warm it runs good though and i get NO CEL?? Why I don't know, but it works.

WHEN IT"S WARM: and I start it once the engine is running, even if it is surging, I can drive away and drive ok. The only thing is that getting it running can be tough. (only once and awhile) And if it is warm and has only been sitting for 5 min or less, it will start up and drive great with no problems AT ALL???


ALDL CABLE:

I did some cable research. I might build one. I will keep you informed if I go that route. Thanks for the input everyone!
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2922

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
07-25-09 09:28 AM - Post#1741565    
    In response to d8nk

Sorry I missed that you did test the fuel pressure.

This system can run ok on 9 PSI, but most of the time when the pressure is on the low end of the specification, if you do more testing you will find that the pressure drops well below spec. at times.

Usually with a good pump, and good regulator, the pressure will be near the top and of the spec.


The finding that it only produced 6 PSI with a key cycle also leads me to be suspicious of the fuel supply.

Another thing you could try is driving it with the o2 sensor disconnected. This way the system will stay in open loop. If the o2 sensor is the problem it could be giving bad readings on what the mixture really is. If it runs well with the O2 sensor unplugged then some O2 sensor testing should be done.

Are there any exhaust leaks before or within a couple feet behind the o2 sensor?
For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
fritz1990 
Senior Member
Posts: 6389
fritz1990
Age: 52
Loc: Kansas
Reg: 02-16-03
07-25-09 10:04 AM - Post#1741589    
    In response to Chevytech

I just did a TBI fuel pump a month ago and it was testing 6 psi with key on and 9 1/2 lbs running. I was having stalling issues. Replaced fuel pump and all is good. I agee fuel pump is suspect. Did you try and pinch the hose off ahead of the gauge to see if fuel pressure went up?

I was a lil' stubborn too about the fuel pressure but it did solve my problem.

Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

http://picasaweb.google.com/fritz199090


 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-27-09 01:49 PM - Post#1742821    
    In response to fritz1990

I had a busy weekend and did not get to all the testing yet but I have a couple questions/comments.

BTW, truck ran great sometimes, not so great other times.

O2 Open/Closed Loop:

The vehicle does not go into closed loop until it is running up to temp and at a constant right? (no heavy accel/decel) And it does not take readings form the 02 until it runs in this closed loop. So some of the problems are during idle/start-up. That would not fit with the 02 sensor since it would still be in open cycle. Unless it is somehow stuck in closed loop. Is that possible? What do you all think about this theory?

No exhaust leaks till after the cat.

Also, what about testing/inspecting pressure regulator. How, and confirm I am looking at the right part. See above...
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
d8nk 
Forum Newbie
Posts: 36
d8nk
Loc: St Paul, MN
Reg: 07-21-09
07-27-09 02:21 PM - Post#1742844    
    In response to d8nk

Oh yeah, on Saturday my truck threw the CEL again. Since I just flashed I thought I would check it out again, WELL totally new codes...

15 - CTS wow that is kind of nice to see...

33 - Map sensor voltage again...

42 - EST voltage issue. Thats new to me, any ideas on that one??

44- That one either re-popped or it is still the old one that would have been in the computer last time the CEL came on.

With the complete change in Codes popping now I am thinking more and more towards electrical fault somewhere... What do you all think?????
89' Chevy 1500 5.7 4X4 TBI
99' Dodge Grand Caravan 3.3 Flex Fuel
95' Pontiac Bonneville 3.8 NA
88.5' Suzuki Samurai
72' Kayot 24' Pontoon w/ 1965 65hp Merc



 
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