# 89 Chevy truck won't stay running



## CarolT (Mar 12, 2009)

1989 Chevy Silverado V8 350 was dying intermittently for about 2 weeks then died and wouldn't start again , replaced fuel pump because that was what seemed to be the problem (we later found out fuel pump was still ok) and fuel filter and it ran for about 1 week, then it died again. Found broken spring in TBI, replaced spring and pressure regulator. Will start and run for several seconds with nice cone, then gas stops and motor dies. Tried a different TBI, same thing. It will rev while running. Any ideas? I really appreciate any help!


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## CarolT (Mar 12, 2009)

Oh, and apparently almost impossible to measure fuel pressure in the lines


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## Darren (May 10, 2002)

Check for a connection on the passenger side where the metal fuel line is routed behind the engine. You'll have to get under the truck to see it. You can buy a T fitting that can be screwed in at that connection that provides a tap to check fuel pressure. There is a chance you got a new fuel pump that was bad. Install the tap and check the pressure to absolutely rule out the pump. If you don't know it already, never let a fuel injected vehicle run out of gas. That's not good for the in-tank fuel pump.

Is the "Check Engine" light coming on?


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## Cabin Fever (May 10, 2002)

Has all this been happening on the same tank of gas? If so, you may have gotten some bad gas at the last fill up.


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## Allen W (Aug 2, 2008)

Check your wiring and make sure every thing is hooked up. I've had them loose or knocked off and they wouldn't run right or not at all.


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## CarolT (Mar 12, 2009)

Different tanks of gas, 3 or 4 different ones. It's DH's truck and he never lets it get below 1/4 tank because he'd heard was big no-no to let it run dry. I will tell him to look for the connection. If you put that connection in, it won't take some specialized gauge they were talking about online as being what was required? Apparently expensive  so I hadn't gone looking for whatever it is. His family has several back-yard mechanics and this one has them all stumped. I'm trying to get suggestions for him to go through when he gets home from work. Also, if the relay is bad, would it run at all? Seen that suggested too...


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## CarolT (Mar 12, 2009)

Oops. Missed a couple of things. His check engine light has been on for the last 3 years. It says one of the sensors is bad and after replacing everything, it wouldn't go away and the shop said it was something wrong in the brain. There is no new code other than the one that's been there, if that helps any?

He rechecked all the wiring. He won't rule out a spot he can't see in the harness somewhere that's gone bad, but it's all hooked up.


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## CarolT (Mar 12, 2009)

Also, in the last 2 or 3 months, we've replaced plugs, wires, coil, rotor button and distributor cap because it was having issues accelerating and he thought it was spark related. I don't know if it's all the same problem, but want to give everything I can think of to maybe nudge any ideas


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## fordy (Sep 13, 2003)

CarolT said:


> Also, in the last 2 or 3 months, we've replaced plugs, wires, coil, rotor button and distributor cap because it was having issues accelerating and he thought it was spark related. I don't know if it's all the same problem, but want to give everything I can think of to maybe nudge any ideas


..........You can have a bad connection in a wiring harness that is Intermittant , thus allowing the truck to run and then die ! Your mechanic probably won't offer to start checking the wiring for shorts because you aren't about to pay him for all the hours it may take him to achieve a firm diagnosis and fix the problem . , fordy


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## coolrunnin (Aug 28, 2010)

My brother has a 91 with similar symptoms turns out the distributor shaft was worn and allowing intermittent spark. Good luck


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## agmantoo (May 23, 2003)

what is the mileage on the engine?


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## farmrbrown (Jun 25, 2012)

CarolT said:


> Different tanks of gas, 3 or 4 different ones. It's DH's truck and he never lets it get below 1/4 tank because he'd heard was big no-no to let it run dry. I will tell him to look for the connection. If you put that connection in, it won't take some specialized gauge they were talking about online as being what was required? Apparently expensive  so I hadn't gone looking for whatever it is. His family has several back-yard mechanics and this one has them all stumped. I'm trying to get suggestions for him to go through when he gets home from work. Also, if the relay is bad, would it run at all? Seen that suggested too...





CarolT said:


> Also, in the last 2 or 3 months, we've replaced plugs, wires, coil, rotor button and distributor cap because it was having issues accelerating and he thought it was spark related. I don't know if it's all the same problem, but want to give everything I can think of to maybe nudge any ideas


I was going to suggest looking at the ignition coil pickup until I saw this last post, but keep in mind you can still get a bad part, new out of the box, or have a bad wire going to it.



CarolT said:


> Oops. Missed a couple of things. His check engine light has been on for the last 3 years. It says one of the sensors is bad and after replacing everything, it wouldn't go away and the shop said it was something wrong in the brain. There is no new code other than the one that's been there, if that helps any?
> 
> He rechecked all the wiring. He won't rule out a spot he can't see in the harness somewhere that's gone bad, but it's all hooked up.


There is one thing odd about this model of Chevy engine, and it might be worth trying to track down exactly what that check engine code was.

The oil pressure switch is connected to the fuel pump relay and sends voltage for about two seconds while cranking and I think uses voltage through that circuit while _running._
That might be one of those odd things going bad that you wouldn't think was the cause of it all.


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## Hidden Hills (Feb 10, 2013)

The ignition module is what controls the injector pulse and plug wire firing. It sounds to me like that's your problem. On this truck the pick-up coil reads a signal from the spinning distributor shaft and then sends a pulsing power signal to the ignition module. The ignition module then uses that signal to fire the injectors and the plug wires. You can take an ignition module to most part stores and have it tested but they usually fail due to heat. By the time you get it to the parts store it has cooled and then tests ok. I would just replace it and see what happens. They are fairly cheap. If you take off the distributor cap and the rotor button and then climb up on the radiator support you can look on the back side of the distributor and you'll see the module. It has a connector on both ends and is held on the distributor with 7/16 head screws. Don't forget to coat the underside of the new one with dielectric grease before installation. There will be a small tube of grease in the box. You can do what you like but if I were a betting man I would say that's your problem.


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## Darren (May 10, 2002)

Once you have the tap connected, it would be simple for a local garage to get a reading on the fuel pressure. Below is a link to one on eBay. There's another, more expensive tap, that temporarily replaces the fuel filter mounted on the frame. I never liked the idea of using one of those and potentially allowing unfiltered gasoline to get to the injectors.

I had a similar problem with an 87 which eventually was tracked to the fuel pump. Eliminate the pump as a potential problem first. I doubt the code/codes stored are going to be much help on an early TBI system. I've had folks tell me to replace the computer behind the glove box. I never did and my 87 now runs fine even though the computer doesn' self check when the engine is first started.

http://www.ebay.com/itm/GM-TBI-inli...Parts_Accessories&hash=item35c013e86c&vxp=mtr


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## CarolT (Mar 12, 2009)

agmantoo said:


> what is the mileage on the engine?


Ummmmm, about 504,000..... :ashamed:

Getting the fitting and the oil pressure sending unit today. And probably an ignition module if he hasn't replaced it already. I thought he had done everything under the distributor cap, but I may be wrong.

ETA I happened to catch my brother who also said oil pressure unit, which makes about the fourth person today LOL Here's hoping!


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## CarolT (Mar 12, 2009)

OK, DH corrected me, only between 3 and 350 thousand on this motor. Not oil sending unit, fuel pressure is good and when he got a noid light in one side of the injector, truck cranked and ran while it lit up, but quit lighting and truck died. Now trying to decide to try pickup coil, pcm, calpak or something else entirely.... I think. (I hate mechanicing....)


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## Darren (May 10, 2002)

Something's killing the signal to the injectors. In my case, 87 chevy, the ignition coil was bad. I could crank forever, no fuel, no ignition. Wouldn't run on starting fluid either. The new coil was bad too. That was a lot of fun.


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## CarolT (Mar 12, 2009)

It will run if fed direct. Got a pcm and calpak from junkyard and still no good  Book says there's another oil sending unit down by the oil filter, so probably try that tomorrow. Of course, there's always the possibility that the junkyard stuff is not good. Going to be a couple of paydays before we can afford to get more parts... Keep any ideas coming, we're pretty well at a loss and appreciate any help!


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## michiganfarmer (Oct 15, 2005)

this would frustrate me so much I just might jerk it out and put in an old carburated 350


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## michiganfarmer (Oct 15, 2005)

Darren said:


> Something's killing the signal to the injectors. In my case, 87 chevy, the ignition coil was bad. I could crank forever, no fuel, no ignition. *Wouldn't run on starting fluid either*. The new coil was bad too. That was a lot of fun.


Good thinking trying the starting fluid. That will at least tell you if yo uhave spark


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## CarolT (Mar 12, 2009)

If you could find one, it might have a carburated one already, but we can't find a decent motor for the old 73 as it is.

We have spark, but only sometimes, if that helps any ideas pop? If there is signal, it runs, if not, won't fire at all


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## Darren (May 10, 2002)

There's a place in Florida that will check and repair vehicle computers. At some point I'll send the one out of the 87 just to find out why it doesn't always store codes. Already looked for wiring problems and loose connections.

Have you checked the ignition coil?


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## SpaceCadet12364 (Apr 27, 2003)

89 has module in the distributor that will give problems like this. it fires the plugs and provides tach signal for fuel injection tbi.


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## Allen W (Aug 2, 2008)

CarolT said:


> If you could find one, it might have a carburated one already, but we can't find a decent motor for the old 73 as it is.
> 
> We have spark, but only sometimes, if that helps any ideas pop? If there is signal, it runs, if not, won't fire at all


You can buy a brand new crate moter delivered for less then $2,000. check out Jegs or Summit Racing. I have a '90 model I plan on putting one in this summer. I priced uesd then rebuilt and finally the crate motors. How they price them around here it isn't that big of spead between them. I don't know how this fits our budget though.


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## Hidden Hills (Feb 10, 2013)

Still say it needs an ignition module. $37.99 at O Reilly auto parts.


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## CarolT (Mar 12, 2009)

Thank you, Hidden Hills! Space Cadet, it was ignition module you were thinking about, too. I'm married to a man who was used to non-computerized models where the ignition module had nothing to do with fuel, so it took a bit to persuade him to try it but when he finally did, I got to say "I read you so!" He now has his old faithful running again and I can get my life back. Thank you! Thank you! Thank you!


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## Hidden Hills (Feb 10, 2013)

Your welcome. Glad to help.


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## nosqrls (Jun 9, 2012)

Your welcome! I had a 90 3500 that did the same thing.There is a bunch of stuff tied in that are not labeled that shut off fuel.


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## keryjacks (Apr 24, 2014)

Okay, after reading all that you have depicted, I really thing the problem was not only related with ignition module but also with spark plugs. Correct me if I am wrong. My family is full of auto heads and your problem is common in nowadays cars. Happy to know that your issue is solved.


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