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Username Post: 1988 r30 454 tbi issues        (Topic#349898)
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-01-18 12:37 PM - Post#2726130    

I hope i am posting in the right section. I have a square body 454ci tbi chevy and it will not stay running in drive or reverse.

Symptoms:
1) Must hold gas down to keep running
2) Very rough running while driving (constantly wants to die)
3) Gas pouring out of evap canister

Helpful tips(I hope): 1988 Chevrolet R30 454TBI with a 454 motor from a motorhome. I have no clue the year motorhome the motor came from.

Any helpful tips on where to start diagnosing this issue would be great. Just bought this thing and it ran perfectly until now. I use only 97 octane in my fuel but i change stations that i fill up (second time filling it since purchase one week ago)


1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
Shepherd 
Frequent Contributor
Posts: 1418

Loc: Lake George, NY
Reg: 11-11-15
03-01-18 01:02 PM - Post#2726132    
    In response to Project_leviathansbc

Welcome to CT. Sounds like it is running rich, if so fuel pressure regulator in the tb is one cause, bad temp sensor, map sensor, any way to check codes or live info at the a diagnostic port? See if the evap cannister is loaded with fuel, check the oil for fuel contamination.Do you have the matching ecm for this engine?



Edited by Shepherd on 03-01-18 01:03 PM. Reason for edit: No reason given.

 
Liberty Valance 
Poster
Posts: 72
Liberty Valance
Loc: Euless,Texas
Reg: 07-21-14
03-01-18 02:32 PM - Post#2726139    
    In response to Project_leviathansbc

Welcome

1974 Cheyenne 10 LWB 350/TH350/AC/4 BBL Quadrajet


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-01-18 05:54 PM - Post#2726173    
    In response to Shepherd

I have no clue motor was swapped before i bought it... It is possible that i do bc it was running fine off the right tank. Out of the left tank i have no turn over just endless cranking.

If it does help at all I know the motorhome motor was originally carb but the guy switched it back to the truck's TBI system.

Under light pump of the throttle black smoke is fired out the pipe and the engine chokes very bad, fuel smell fills the air but it smells like laquer thinner? Possible to still have faulty fuel in the system? I've burned through 2 full tanks.

Truck does not have a functioning temperature sensor or oil pressure sensor. (Or even one that i have been able to locate)



1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


Edited by Project_leviathansbc on 03-01-18 09:08 PM. Reason for edit: Forgot some useful info

 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4014
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
03-01-18 11:36 PM - Post#2726210    
    In response to Project_leviathansbc

Start by checking your fuel pressure.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-02-18 06:21 AM - Post#2726224    
    In response to CowboyTrukr

And if the fuel pressure is not right how would i adjust it?

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4014
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
03-02-18 06:52 AM - Post#2726226    
    In response to Project_leviathansbc

Only three things: filter, pump or pressure regulator like Shepherd said. Most often, it’s the pump that’s failing.

Start by replacing your filter first.

With dual tanks, you have two pumps. You may even have a second fuel filter. I don’t have experience with the dual tank setup. Others here do.

The thing is that the pump is almost always the culprit.

How’s you fuel spray pattern? Take a bright light or even a timing light and shine it in the throttle body while it’s running. You should see a steady cone shape all the time. No drops or dribbling.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-02-18 08:45 PM - Post#2726283    
    In response to CowboyTrukr

Fuel spray appears conical. I don't run it for long without the filter on top of the throttle body. But it seems to be a nice even spray. No drops that i can tell. I will replace the filter tomorrow whilst at work and touch base.

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-03-18 09:28 AM - Post#2726310    
    In response to Project_leviathansbc

Welcome to the site. Fuel pressure will cause all kinds misdiagnosis. I know. I’ve chased ghost problems only to find a bad fuel pump. GM didn’t put a testing port. You need a special adaptor. You can test a different way. You have to be really careful. With a cold engine, pour a little fuel down the throttle body. Crank it. If it starts and runs a few seconds, the fuel pump or delivery is not what working properly. If you do see a spray, check for spark. If the injectors are firing, the pick up coil is working. You can ohm it out to check it too. Remove and have the ignition module checked at a parts store.

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-03-18 04:07 PM - Post#2726333    
    In response to gchemist

I do appreciate that help but come to find out the a hole before me tried to convert it to a single tank system running both tanks at one time. I have open hoses and cut lines everywhere so ill have to start from scratch and repost once i get the fuel set back to normal....

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-03-18 04:10 PM - Post#2726334    
    In response to Project_leviathansbc

Do you guys think it would be better to run a carb instead? My eventual goal is to run a big lopey cam and a high-rise intake on the truck with a turbo 400 trans

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
Shepherd 
Frequent Contributor
Posts: 1418

Loc: Lake George, NY
Reg: 11-11-15
03-03-18 06:21 PM - Post#2726337    
    In response to Project_leviathansbc

The stock tb system will not be happy with an aggressive cam.



 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-04-18 04:53 AM - Post#2726375    
    In response to Shepherd

TBI is very reliable when everything is working correctly. Work out the bugs. It's worth it. I'll email you a TBI troubleshooting guide. I forgot to mention it earlier.

Is your truck a four door? Dually? Wrecker?

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-04-18 06:45 AM - Post#2726380    
    In response to gchemist

Truck is a square body 4 door dually. With an 8ft bed and dual gas tanks. Turbo 400 trans that was just rebuilt.

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-05-18 05:01 AM - Post#2726468    
    In response to Project_leviathansbc

Nice!! I've seen a few still driving around Texas. Did you receive the TBI troubleshooting guide?

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-05-18 05:32 AM - Post#2726471    
    In response to gchemist

Yes i did im going to be running through it but just a thought.

The guy before me hooked up both tanks to run at the same time. So if i am pulling the same ammount of fuel from both tanks at the same time to try and run the truck could it be causing this issue?

Or maybe because one tank is a main and the other is auxillary it is just pulling air through the one tank now? Since i have only filled one side?

Edit: the truck started acting up on the way home when the gauge reached half a tank. (Didn't even fill it yet) so possible 25gal on one side and 15 gal on the other? So since i drained the one fully and the other half way it is acting up?

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


Edited by Project_leviathansbc on 03-05-18 05:40 AM. Reason for edit: Tanks tanks and more tanks

 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-05-18 11:22 AM - Post#2726510    
    In response to Project_leviathansbc

Liquid will take the path of least resistance. Fix the switch valve hoses. If it's truly pulling from both tanks, that's two pumps supplying fuel. TBI only requires 13-15 PSI to run. Any more or less pressure will make it run bad.

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-05-18 04:48 PM - Post#2726548    
    In response to gchemist

10-4 I will look into the fuel pressures tomorrow as well as start to re-run new fuel lines to the bank switch/ selector valve. Does anyone know the orientation for these? The Haynes Repair Manual that I have does not have the diagram for dual tanks let alone the selector valve set up.

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-06-18 05:44 AM - Post#2726620    
    In response to Project_leviathansbc

Go here and download a factory manual.
http://forum.73-87chevytrucks.com/smforum/index.ph...

I'm not sure if hose locations are detailed. I'll search around for a detailed pic or routing.

I have one of these for TBI pressure testing.
https://www.amazon.com/Actron-CP7817-Throttl e-Inje...
They are not easy to find anymore. Look around. I've seen a few on Craigslist or ebay.

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-06-18 11:50 AM - Post#2726662    
    In response to gchemist

Great help ill look into those manuals and go buy a tester!

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-14-18 04:52 AM - Post#2727543    
    In response to gchemist

Fuel pressure at the TB is 17psi

I found a diagram for the dual tank set up so that is my next project.

On this diagram i could use some help with the inlet and outlet locations for the right and left tank as well as what the black locations are for if anyone knows??

https://goo.gl/images/0LDhQl


1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


Edited by Project_leviathansbc on 03-14-18 04:54 AM. Reason for edit: Link

 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
03-18-18 05:06 AM - Post#2728019    
    In response to Project_leviathansbc

Below are pics of tank routing lines.

Attachment: valve.jpg (30.87 KB) 15 View(s)


Dual tank valve.


Attachment: 2104_0135.jpg (49.62 KB) 14 View(s)


Carb truck line routing.


'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
Project_leviathansbc 
Forum Newbie
Posts: 15
Project_leviathansbc
Age: 22
Loc: Belleview FL
Reg: 03-01-18
03-19-18 11:07 AM - Post#2728161    
    In response to gchemist

Gchemist. You are a freaking lifesaver man thank you so much. Will tackle that this month and get back to y'all

1988 chevy r30 454TBI
1995 g20 conversion 350MPI
1998 chevy k1500 350MPI


 
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