The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Engine & Drivetrain

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 12-16-2013, 09:19 PM   #1
87chevyk10
Registered User
 
Join Date: Sep 2013
Location: Spring grove pa
Posts: 14
Engine randomly shuts off

Hi, i am working on a 89 305 tpi for a guy. he said that when he is driving it randomly shuts off and is very inconsistent when it does shut off. he can not guess when its about to shut off. after it shuts off it wont start up until 5 minutes later. here is a list of things he changed or did:
tune up
fuel filter
distributor
Fuel injectors
Fuel pressure regulator
strainer/ float sending
Ecm (twice)
ignition switch
02 sensor
tps
egr valve
maf sensor
lac valve
ignition module
coil
2 relays
so can you guys help me out here and tell me what possibly it could be?
After it shuts off it starts up again but the idle goes up and down. when u hit the gas it shuts off. and when you start it up again the idle still will go up and down but when u hit the gas it would stay running. And the guy i am working on this for replaced all the things listed above by a garage and by his self. And now i am trying to figure this out for him. he took it to a couple of garages and they dont know.
87chevyk10 is offline   Reply With Quote
Old 12-16-2013, 09:49 PM   #2
LONGHAIR
just can't cover up my redneck
 
Join Date: May 2004
Location: Columbus OH
Posts: 11,414
Re: Engine randomly shuts off

Randomly shutting off pretty much has to be an electrical issue, but "unpredictable" makes it far worse to figure out.
Could be as simple as a loose ground.
Most of the things that have been replaced could make it run badly (or not at all) if they were bad, but the random shut off that runs fine the rest of the time is not easily connected to most of them.
Were these new ECMs?
__________________
You can review the site's rules here.



Quote:
Originally Posted by Longhorn Man View Post
As for reading directions...
The directions are nothing but another man's opinion.
Learn from the mistakes of others, you won't live long enough to make them all yourself...

Bad planning on your part does not necessarily constitute an instant emergency on my part....

The great thing about being a pessimist is that you are either pleasantly surprised or right.
LONGHAIR is offline   Reply With Quote
Old 12-16-2013, 09:50 PM   #3
cableguy0
Senior Member
 
Join Date: Apr 2000
Location: Delta,Pa
Posts: 14,948
Re: Engine randomly shuts off

Was the fuel pump replaced? How much fuel pressure does it have? I have seen a few Gm vehicles recently that show 50lbs+ of fuel pressure but are actually not moving any fuel just building air pressure. No clue how it manages to do it but I have seen it 4 or 5 times in the last year. Open the valve on my gauge set and fuel barely dribbles out showing 50psi or more.
__________________
Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.
cableguy0 is offline   Reply With Quote
Old 12-16-2013, 09:52 PM   #4
cableguy0
Senior Member
 
Join Date: Apr 2000
Location: Delta,Pa
Posts: 14,948
Re: Engine randomly shuts off

Also is it throwing any codes at all? The computers in the obd1 gms are notoriously horrible and the replacements from the parts store aren't much better.
__________________
Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.
cableguy0 is offline   Reply With Quote
Old 12-16-2013, 10:18 PM   #5
87chevyk10
Registered User
 
Join Date: Sep 2013
Location: Spring grove pa
Posts: 14
Re: Engine randomly shuts off

Quote:
Originally Posted by LONGHAIR View Post
Randomly shutting off pretty much has to be an electrical issue, but "unpredictable" makes it far worse to figure out.
Could be as simple as a loose ground.
Most of the things that have been replaced could make it run badly (or not at all) if they were bad, but the random shut off that runs fine the rest of the time is not easily connected to most of them.
Were these new ECMs?
Tried 2 different brand new Ecms. I will go through and check the grounds tomorrow thanks.
87chevyk10 is offline   Reply With Quote
Old 12-16-2013, 10:20 PM   #6
87chevyk10
Registered User
 
Join Date: Sep 2013
Location: Spring grove pa
Posts: 14
Re: Engine randomly shuts off

Quote:
Originally Posted by cableguy0 View Post
Also is it throwing any codes at all? The computers in the obd1 gms are notoriously horrible and the replacements from the parts store aren't much better.
New fuel pump. I dont think it's throwing any codes but I will double check tomorrow. And also will check fuel pressure and stuff tomorrow thanks.
87chevyk10 is offline   Reply With Quote
Old 12-16-2013, 10:21 PM   #7
Special-Ed
Registered User
 
Special-Ed's Avatar
 
Join Date: Jul 2013
Location: Floriduh
Posts: 386
Re: Engine randomly shuts off

did you check the idle circuit(air) and clean the throttle butterfly... carbon build up can cause this exact issue... it was very common with the quad4 and other motors from pontiac/gm and other motors from back in the day.
__________________
Ed will be known as the Tiger Woods of the integration business
Special-Ed is offline   Reply With Quote
Old 12-16-2013, 10:39 PM   #8
87chevyk10
Registered User
 
Join Date: Sep 2013
Location: Spring grove pa
Posts: 14
Re: Engine randomly shuts off

Quote:
Originally Posted by Special-Ed View Post
did you check the idle circuit(air) and clean the throttle butterfly... carbon build up can cause this exact issue... it was very common with the quad4 and other motors from pontiac/gm and other motors from back in the day.
No, I will tomorrow thanks! Keep throwing stuff at me that I can do.
87chevyk10 is offline   Reply With Quote
Old 12-17-2013, 10:39 AM   #9
68gmsee
Active Member
 
68gmsee's Avatar
 
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
Re: Engine randomly shuts off

I had the throttle position sensor act up on one of my vehicle and do strange things with the idle and surging. Since you show it's been replaced, check the connector very carefully for loose, broken or corroded wires. Maybe try to follow it back.
__________________
68 GMC 250/3 speed Saginaw p/b p/s
69 Chevy 350/350 currently in pieces still lookin for a cab
06 Trailblazer
I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive...
68gmsee is offline   Reply With Quote
Old 12-17-2013, 10:43 AM   #10
Gumby
Registered User
 
Gumby's Avatar
 
Join Date: Dec 2008
Location: NW-Ohio
Posts: 2,525
Re: Engine randomly shuts off

Did ya open the ECM's and inspect the board with eyes ands nose for burnt section?

won't always toss a code.

had a CCP valve mess with me for a few years.

canister Control Purge
Gumby is offline   Reply With Quote
Reply

Bookmarks

Tags
305


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 03:15 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com