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Username Post: excessive fuel consumption 4.3L '93 blazer        (Topic#176452)
gfng 
Forum Newbie
Posts: 15

Reg: 11-26-07
12-06-07 08:17 AM - Post#1312069    

Using a lot of fuel. Starts like flooded - need to put pedal to floor then starts OK. Starts great when cold. (real cold). Idles like stuck carb (yes TBI) heavy fuel smell. No Codes.

Any ideas where to start?

Thanks


 
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427SS65 
"10th Year" Platinum Supporting Member & Moderator
Posts: 13279
427SS65
Age: 68
Loc: St. Louis, MO
Reg: 12-11-03
12-06-07 12:00 PM - Post#1312247    
    In response to gfng

Probably the spider unit inside the intake manifold.
Tom 65-70 Full Size Team Moderator

View My Photos Here

65 Impala SS Tahitian Turquoise


 
ExtraScrews 
Senior Member
Posts: 284

Loc: Kansas, USA
Reg: 08-19-04
12-06-07 05:02 PM - Post#1312454    
    In response to gfng

I would carefully inspect the throttle body when the engine is running to see if there is any fuel leaking from the pressure regulator or connections to the injectors.
1995 S10 (4.3 5-speed)

What is your malfunction?


 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2993

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-06-07 06:45 PM - Post#1312528    
    In response to gfng

The first thing I would test is the coolant temp sensor because it is one of the criteria used by the ECM/PCM to determine how much fuel to inject. It screws into the intake manifold by the Thermostat.

To test the coolant sensor, unplug the wire connector and test the resistance across the two terminals of the SENSOR with an ohm meter.


Coolant sensor approximate resistance specifications:
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.

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.


 
gfng 
Forum Newbie
Posts: 15

Reg: 11-26-07
12-08-07 07:29 AM - Post#1313648    
    In response to Chevytech

Thanks everyone for all your help. Here's an update. The saga continues...

Checked the temp sensor (seemed the easiest)
use a spare electrical clip, DMM, an infared temp sensor.

Results

1550 ohms @ 85.5
2500 ohms @ 64
3180 ohms @ 69 (moved the IR to a closer position)
6950 ohms @ 42

While not exactly to specs. I thought close enough to be good. On to the spider. Fortunatly I have a spare parts vehicle (at least I thought. It had a recently replaced spider).

Replaced spider w/ new intake gasket. About an hour time. Boom fires right up. several times, happy, happy. Off to the favorite Tavern to show off my success, Alas it got worse than before. 6 gallons of fuel down the pipes. 20 miles to my favorite haunt. Extra rich code popped up. No kidding. My friends tell me I have a good sense of humor, which is good. It's mighty chilly today about zero out but I'll hold off to see if I get any suggestions. I think the fuel connection (quick clip) failed.

One post here suggested I can visual check the injection. Can you fire it up or pressurize the system with the intake off? seems sensors would go wild but might be helpful.

Again thanks for all your time and help

 
gfng 
Forum Newbie
Posts: 15

Reg: 11-26-07
12-08-07 07:38 AM - Post#1313656    
    In response to gfng

I know I mentioned TBI in my first post, and should have specifies spider. Although the spider is a glorified throttle body injector. Unless the defining criteria is location of throttle plates, before or after. Sorry, babbling, better go get more coffee

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2993

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-08-07 08:03 AM - Post#1313672    
    In response to gfng

  • Quote:

1550 ohms @ 85.5
2500 ohms @ 64
3180 ohms @ 69 (moved the IR to a closer position)
6950 ohms @ 42

While not exactly to specs. I thought close enough to be good.

Yes, it is close enough.

  • Quote:
Replaced spider w/ new intake gasket. About an hour time. Boom fires right up. several times, happy, happy. Off to the favorite Tavern to show off my success, Alas it got worse than before. 6 gallons of fuel down the pipes. 20 miles to my favorite haunt. Extra rich code popped up. No kidding.

The plastic fuel supply and return hoses that bring the fuel to and from the spider can crack and leak fuel into the engine. This is a fairly common problem.

  • Quote:
One post here suggested I can visual check the injection. Can you fire it up or pressurize the system with the intake off?


I put a fuel pressure gauge on then turn on the key on without cranking the engine to see if pressure holds or falls, after the 2 second prime. If pressure falls, I restrict flow in the return line, to test the regulator.

Now that you have had it apart and know how quickly it can go, you may just want to remove the upper plenum and take a look at the plastic fuel supply hoses.

I turn the key on WITHOUT cranking the engine with the upper plenum off to pressurize the system to check for leaks.

DON”T start or crank the engine with it apart.
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.


 
gfng 
Forum Newbie
Posts: 15

Reg: 11-26-07
12-08-07 08:11 AM - Post#1313677    
    In response to Chevytech

Thanks chevyTech.
I guessed as much. Should of done this pressure test the first time with the plenum off. Sometime speed kills, usually about the third time I get it, hopefully I can do it on the second try.

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2993

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-08-07 08:16 AM - Post#1313684    
    In response to gfng

You're welcome!

Let us know what you find.
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.


 
427SS65 
"10th Year" Platinum Supporting Member & Moderator
Posts: 13279
427SS65
Age: 68
Loc: St. Louis, MO
Reg: 12-11-03
12-08-07 03:47 PM - Post#1313990    
    In response to gfng

GM calls those two fuel hoses a "Nut Kit". Screwy!

That used spider assembly may not be better than the one you took off.

The spider assembly takes 53 PSI of fuel pressure to "poppet" properly. Make sure you have that kind of fuel pressure at the test point (even with the motor running).
Tom 65-70 Full Size Team Moderator

View My Photos Here

65 Impala SS Tahitian Turquoise


 
gfng 
Forum Newbie
Posts: 15

Reg: 11-26-07
12-12-07 03:10 PM - Post#1317029    
    In response to 427SS65

The Saga continues:
I know new is better, but when you have and buy one get one free, you use the parts at hand first. (at least that was the idea for the tranny). But there are many other good (recently replaced parts) still on the spare.
Yes it was the supply line had cracked so I replaced that.

Checking the fuel pressure, it checked out OK. I didn't catch the fuel leak. So after I put out the ensuring fire. (Lots of excitement and panic) How come I can't find a fire extinguisher when I need it. Lots of snow and windsheild washer fluid and water later the fire was out. I thought I need a cooling out period. Replaced the leaking pressure release valve. But no go. Started checking my burnt wiring harness for breaks or meltdowns. this took a while, not much room back there. replace the harness going to the coil, replaced the pickup sensor, (found out the cap retaing bolts are stripped). But none of the harness wires were burnt. Walk away....Started checking voltages. Had spark, power to the fuel solennoid, spark plugs were dry.????? I think it has a death wish. Next I activated the fuel solenoid. Low an behold she sputters. Try again and fires to life, but I can flood it out. PLaying with it a little more I get her to run on her own. I had also noticed it was very low on fuel but still had a bar, so I put more fuel in the tank and now she running better than ever (not a miss, smooth idle). I still have to check the cold start tommorrow till my faith is restored, and I can get after my originally tranny problem. Sorry about the long post, when things happen, they really happen.

Again thanks for the help

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 2993

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-12-07 06:21 PM - Post#1317154    
    In response to gfng

Thanks for the update!
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.


 
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