GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi there, I am Cam. I am sorry to hear about this issue, it’s a bit of a pain but I will help you out.The electric pump you hear is not for the fuel pump, this engine does not use an electric lift pump. IT has only the mechanical lift pump mounted on the back if the injector pump. So the only way to prime it after running out of fuel is to open the bleeder on the top of the fuel filter housing, then pump until fuel comes out. This can take 60-100 pumps. Then after it gets fuel, close the bleeder and continue pumping until it gets stiff. This will take many pumps. You can have someone crank the engine while you pump during the second portion of the bleeding/priming sequence until it runs. This will get you going. Once fuel does come out of the bleeder you should notice a different feel in the plunger. IF not then its possible the primer pump is failing. I have replaced the fuel filter head for issues with priming.Please try this and let me know what you find.
Sorry for the delay. I was on a road test.
IS yours a dual tank setup?
OK, sounds good. IF you keep pumping with the bleeder closed, does fuel come out anywhere?
Does it keep running if you keep pumping the plunger?
But it starts and stops, is there any question about the type of fuel put in? Was it by chance Gas or really old fuel that may be contaminated?
OK, This is strange, usually the pumping/priming makes it run. IS there any warnings on the dash?
the spring is a glow plug indicator. At this moment after everything, does it still just start and stall?
OK, we need to try a bit more fuel then. You might be lower than you thought. IF this does not change it then we might be looking at something deeper like a pump, but that’s a major issue, and with only running out of fuel, it usually does not end up like that.
Ok, and pump after it gets stiff several times to see if that changes anything.
It my have been. The fact it does not remain running and you cannot make it stay running with the primer suggest it may be an injection pump issue, is there a chance you can measure the vacuum on the system at the test port?
There is a black test cap with a port under it that measures the vacuum between the pump and filter. WE need to see what the vacuum that the injection pump is pulling.
Perhaps I should ask when you last changed the fuel filter?
OK, can we try a bit more fuel just in the off chance?/Otherwise we need to get it scanned and see what the computer is seeing.
Ok, I really hope that’s it. IT strange that it did not run by now.
It makes no sense unless the lack of fuel finished off the pump. These were bad for the injection pump ceramic ball inside failing.
So do I. To be honest I am hoping its just an issue with how you primed it but it does not sound like it is. .
Odd the timing of it. Glad you got it sorted out. Put some moth balls under there to keep them out.