For the last six months my truck will occasionally not start. It turns over great and runs for just a second then dies. A lot of times if I wait a few hours it will then start. The truck only has 54000 miles on it. Any ideas?
2004 GMC Sierra won't start?
- Thread starter Dianne H
- Start date
It sounds like the fuel pump is weak. Disconnect the fuel line just before the filter and have a helper crank the motor while placing the end of the line into a plastic container. Observe the fuel flow from the disconnected line to see if there's a steady stream of fuel. If not, you may need to replace the fuel pump.
Make sure you purchase the pump from the dealer using the VIN number. GM made a large variety of fuel pumps for this vehicle and getting the correct aftermarket unit is a hit and miss proposition.
Make sure you purchase the pump from the dealer using the VIN number. GM made a large variety of fuel pumps for this vehicle and getting the correct aftermarket unit is a hit and miss proposition.
Molson02536
New member
You may be weak on fuel pressure . Even a couple of lbs low on a cold start will cause a no start. Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems. One test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem.
Run the full fuel pressure test and post back pressures.
Here is the guide lines on testing:
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure. Cold start should be 64-65 lbs of pressure. If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
The 75-85 is only a check on the capable full pressure of fuel pump.
What are the pressure readings that you have done. What are your cold start pressure readings? Post back what you have, be glad to help you get your Sierra running again.
Almost forgot, your ground wire to your fuel sending unit is separate from the wire harness and is grounded on the frame. Inspect it for corrosion or any damages and repair , a bad ground can cause a weak fuel pump and cause you extra expense that was not needed.
Oh if the engine does not start with the carb cleaner, then it's going to be an ignition system issue and we can start with that once we determine that it's not fuel issues. Good luck friend.