No Start Situation

[Xman]

87 R10 has spark and fuel but won't start. Was driving and engine shut down. Pulled plug and grounded it and there is spark. Had wife crank truck and saw injectors squirt fuel. Any ideas as to what has happened and what to look for?

 

[gpmorgan]

Do you hear the fuel pump running? It could have jumped time.

 

[chengny]

First check in this type of situation (non-start but with apparent spark and fuel flow) is whether the ECM is functioning. Simple diagnostic:

Turn ignition switch to RUN and - without going to START - check for the presence of a SERVICE ENGINE SOON warning light.

 

[Xman]

Yes. The SERVICE ENGINE SOON LIGHT is on with the key in the on position. Not sure what "jumping time" means for the fuel pump. Is that controlled by the ECM?

 

[chengny]

Yes. The SERVICE ENGINE SOON LIGHT is on with the key in the on position. Not sure what "jumping time" means for the fuel pump. Is that controlled by the ECM?

I think he was offering two separate possible causes.

1. That the fuel pump was not being energized - as could be verified by hearing it

2. That the proper ignition timing had been lost - because the the timing chain had jumped a tooth.

 

[Xman]

Thanks for clearing that up. I do see the fuel injectors pulse when cranking the engine. As far as the timing chain...I had the top end done about a month ago due to a leaking head gasket. Engine also received a new timing chain. Could this be an ignition control module if there is spark?

 

[4WDKC]

Thanks for clearing that up. I do see the fuel injectors pulse when cranking the engine. As far as the timing chain...I had the top end done about a month ago due to a leaking head gasket. Engine also received a new timing chain. Could this be an ignition control module if there is spark?

possible, if this is the original dist. Id recommend replacing it, anyway they are know to allow contact withing the pickup coil when the bushings get worn. Before you do that make sure you get a fuel pressure gauge on it, the pump can be on and make enough pressure to fire the injectors sporadically but not enough to make the truck run.

 

[gpmorgan]

I think he was offering two separate possible causes.

1. That the fuel pump was not being energized - as could be verified by hearing it

2. That the proper ignition timing had been lost - because the the timing chain had jumped a tooth.

Thx chengny. That's what I was saying. Shouldn't be a timing issue since the chain was recently changed. I agree that fuel pressure check would be the next move.

 

[1987 GMC Jimmy]

What kind of spark did you see when you grounded the plug? Should have been white with maybe a bluish tinge. Yellow-orange spark is a weak one. If you're getting a good spark, you can try priming the TBI with a little gasoline like a carburetor. I'd also start moving towards fuel pressure. You can borrow a pressure test kit from AutoZone and tee it in at the fuel filter location to see what it is.

 

[chengny]

Yes. The SERVICE ENGINE SOON LIGHT is on with the key in the on position. Not sure what "jumping time" means for the fuel pump. Is that controlled by the ECM?

Have you checked for codes? Since the SES light won't go out until the engine fires (and yours isn't firing), you won't be able to tell if the ECM is throwing any DTC's. Scan the ECM for any codes that were present when the engine shut down. Here is how to do it - in case you are not sure:


Pull the ALDL cover. Locate the A & B terminals as shown below. Make a jumper (a paper clip is fine) and connect terminals A & B.

Turn the ignition switch to RUN. You should see the SES light flash a 12 code (1 flash - pause - 2 flash) 3 times.`Then any stored codes will follow. After any stored codes have been flashed, the 12 code will flash one last time.

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[chengny]

BTW - have you tried starting/running with ether (i.e. starting fluid)? That is always my first diagnostic.

If it will start - and stay running - by spraying ether down the throat...the problem is related to fuel supply.

If there is no difference...forget the fuel system and look at an ignition problem.

 

[Xman]

Thanks to all that have responded. Truck will have to wait until this Monday or Tuesday as my time will be taken up by hurricane prep. Hopefully I will have internet. Hopefully there will be power.

 

[74 Shortbed]

Good luck and stay safe out there..

 

[Xman]

Well....made it thru the hurricane with no issues other than too much yard cleanup and assisting the neighbors. I did the ALDL test and it only showed 12. No other codes. I am going to rent a fuel pressure tester next and see what happens. I did pour fuel into the TBI to see if it would fire. It did not. I had pulled the computer out to have it tested and the only place that I knew of doesn't test computers that old. This prior to doing the ALDL test. Would that have cleared any other codes?

 

[gpmorgan]

As long as the spark plugs are not fouled and the ign is firing, the fuel down the tb should have resulted in something.