Need Help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Johnny Merder · 11-23-2013, 09:47 AM

I'm working on a 87 TBI 350 for a friend of a friend (I know better), the thing will run perfect with a shot of carb spray. it will not crank and start without the shot of carb spray? The problem is that the engine is cobbed into a jeep and the wiring isn't the best. Does anyone have any Ideas on this? It is in my shop and needs to leave, I'm just trying to help a guy out. But now I need the help.

Thanks in advance

Sodell · 11-23-2013, 10:45 AM

Has it ran since the swap?

**hatzie** · 11-23-2013, 10:53 AM

Runs on carb spray and stalls?

notallthere · 11-23-2013, 10:59 AM

If it runs just on the carb spray then it is not getting enough fuel. I would check the fuel pump electrical connections to ensure the proper 12V and that the fuel pressure is around 7-9 PSI.

Johnny Merder · 11-23-2013, 11:40 AM

No, sorry It actually will run perfect forever once it starts.

Johnny Merder · 11-23-2013, 11:41 AM

It doesn't need the carb spray after it starts

Johnny Merder · 11-23-2013, 11:48 AM

Missed one, sorry it has ran for a few years in this JEEP.

franken · 11-23-2013, 11:49 AM

You might want to start googling 87 GM TBI ECM no fuel. Interesting that it has spark and no gas.

Maybe back then the EFI was computer controlled but not the ignition. Those were the early days of EFI...

If it was me, I'd check to see if the ignition is run off the ECM.
Is it squirting fuel at all in the TB?
Find the ECM and make sure it's getting good power?
Clean all electrical connections including grounds. Electronics in vehicles dislike bad power and signal.

Just guessing...

kserieskid · 11-23-2013, 12:35 PM

I have an 87 tbi stock in my 3/4 ton here have been my issues and fixes for no fuel problems

the wires for the two nodes would get jamed underneath the air cleaner and short out poping the fuse under the dash

fuel pump went out slowly causing the truck to stall and not be very driveable.

also one of the nodes itself went bad thoes are the little thingys the wires for the tb go to inside you can go to most autoparts stores and rent a set of node testers cheap or any place like harborfreight sears craftsman ect

Sodell · 11-23-2013, 03:27 PM

I would check the fuel pump relay. I had a buddy in the same predicament and messed with it for a good amount of time before I figured it out. Unhook the battery and see if it will start after re-hooking.

Does it die while driving around?

Sodell · 11-23-2013, 04:06 PM

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**hatzie** · 11-23-2013, 04:48 PM

In 87-91 RV chassis TBI the ECM controls the fuel pump power. It should cycle for @ 20seconds after the ignition is switched from off to on. If the fuel pump relays with this provision along with the wiring from the ECM were overlooked in the conversion then it'll have issues starting.

Hard start could also be the "Starter-is-Cranking" signal. This feeds a 12 volt signal to the ECM when the starter is engaged to allow enrichment and cancel diagnostics until engine is running.

If the fuel pump check valve on a GM TBI truck is leaky then you'll have hard starts. If this was overlooked on the install into the Jeep then the fuel will drain back to the tank making for hard starts.

The Complete GM 87-91 RV service manual sets are in my signature.

Johnny Merder · 11-24-2013, 08:44 AM

Thanks everyone, I have some place to go now to start looking.

Sabaka454 · 11-24-2013, 11:02 AM

You need to check for injector pulse when cranking and check fuel pressure.

11-23-2013, 09:47 AM	#1
Johnny Merder Registered User Join Date: Jun 2011 Location: Jasper, In Posts: 109	Need Help! I'm working on a 87 TBI 350 for a friend of a friend (I know better), the thing will run perfect with a shot of carb spray. it will not crank and start without the shot of carb spray? The problem is that the engine is cobbed into a jeep and the wiring isn't the best. Does anyone have any Ideas on this? It is in my shop and needs to leave, I'm just trying to help a guy out. But now I need the help. Thanks in advance

11-23-2013, 10:45 AM	#2
Sodell Registered User Join Date: Mar 2013 Location: Fayetteville Arkansas Posts: 830	Re: Need Help! Has it ran since the swap? __________________ Scott 87 Chevy 2WD SWB, 88 4x4 LWB http://67-72chevytrucks.com/vboard/s...d.php?t=610652

11-23-2013, 10:53 AM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Need Help! Runs on carb spray and stalls? __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

11-23-2013, 10:59 AM	#4
notallthere Registered User Join Date: Nov 2011 Location: sarnia ontario canada Posts: 211	Re: Need Help! If it runs just on the carb spray then it is not getting enough fuel. I would check the fuel pump electrical connections to ensure the proper 12V and that the fuel pressure is around 7-9 PSI.

11-23-2013, 11:40 AM	#5
Johnny Merder Registered User Join Date: Jun 2011 Location: Jasper, In Posts: 109	Re: Need Help! No, sorry It actually will run perfect forever once it starts.

11-23-2013, 11:41 AM	#6
Johnny Merder Registered User Join Date: Jun 2011 Location: Jasper, In Posts: 109	Re: Need Help! It doesn't need the carb spray after it starts

11-23-2013, 11:48 AM	#7
Johnny Merder Registered User Join Date: Jun 2011 Location: Jasper, In Posts: 109	Re: Need Help! Missed one, sorry it has ran for a few years in this JEEP.

11-23-2013, 11:49 AM	#8
franken Registered User Join Date: Jun 2013 Location: Somewhere Posts: 3,124	Re: Need Help! You might want to start googling 87 GM TBI ECM no fuel. Interesting that it has spark and no gas. Maybe back then the EFI was computer controlled but not the ignition. Those were the early days of EFI... If it was me, I'd check to see if the ignition is run off the ECM. Is it squirting fuel at all in the TB? Find the ECM and make sure it's getting good power? Clean all electrical connections including grounds. Electronics in vehicles dislike bad power and signal. Just guessing...

11-23-2013, 12:35 PM	#9
kserieskid Registered User Join Date: Nov 2013 Location: Nashua NH Posts: 27	Re: Need Help! I have an 87 tbi stock in my 3/4 ton here have been my issues and fixes for no fuel problems the wires for the two nodes would get jamed underneath the air cleaner and short out poping the fuse under the dash fuel pump went out slowly causing the truck to stall and not be very driveable. also one of the nodes itself went bad thoes are the little thingys the wires for the tb go to inside you can go to most autoparts stores and rent a set of node testers cheap or any place like harborfreight sears craftsman ect __________________ 1987 GMC 3/4 ton 1981 chevy step side 1998 chevy blazer 1999 Subaru legacy (DD)

11-23-2013, 03:27 PM	#10
Sodell Registered User Join Date: Mar 2013 Location: Fayetteville Arkansas Posts: 830	Re: Need Help! I would check the fuel pump relay. I had a buddy in the same predicament and messed with it for a good amount of time before I figured it out. Unhook the battery and see if it will start after re-hooking. Does it die while driving around? __________________ Scott 87 Chevy 2WD SWB, 88 4x4 LWB http://67-72chevytrucks.com/vboard/s...d.php?t=610652

11-23-2013, 04:06 PM	#11
Sodell Registered User Join Date: Mar 2013 Location: Fayetteville Arkansas Posts: 830	Re: Need Help! [IMG][/IMG] [IMG][/IMG] __________________ Scott 87 Chevy 2WD SWB, 88 4x4 LWB http://67-72chevytrucks.com/vboard/s...d.php?t=610652

11-23-2013, 04:48 PM	#12
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Need Help! In 87-91 RV chassis TBI the ECM controls the fuel pump power. It should cycle for @ 20seconds after the ignition is switched from off to on. If the fuel pump relays with this provision along with the wiring from the ECM were overlooked in the conversion then it'll have issues starting. Hard start could also be the "Starter-is-Cranking" signal. This feeds a 12 volt signal to the ECM when the starter is engaged to allow enrichment and cancel diagnostics until engine is running. If the fuel pump check valve on a GM TBI truck is leaky then you'll have hard starts. If this was overlooked on the install into the Jeep then the fuel will drain back to the tank making for hard starts. The Complete GM 87-91 RV service manual sets are in my signature. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

11-24-2013, 08:44 AM	#13
Johnny Merder Registered User Join Date: Jun 2011 Location: Jasper, In Posts: 109	Re: Need Help! Thanks everyone, I have some place to go now to start looking.

11-24-2013, 11:02 AM	#14
Sabaka454 Registered User Join Date: Jul 2005 Location: CT Posts: 278	Re: Need Help! You need to check for injector pulse when cranking and check fuel pressure.



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