hello. I have a 1997 gmc jimmy that has been having problems lately. For the past 2 weeks, it would bog a little and periodically while driving and ideling. It also made a noise and started hard, but it still started. I went out to start it this morning, and the noise is worse than before and it will not start. The noise is a mix between a large rattle and puff. I already did distributor and spark plugs. What could the problem be? The rattle is more like the engine rattleing. It hesitates to start. Thank you
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. it's a lot safer, if you get a intake or engine full of starting fluid it can blow things like the poppet valve. Carb cleaner will start it if it is a fuel problem and lot safer. 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.
1. Check cold start fuel pressure.
2. Check engine running fuel pressure.
3. 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.
If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.
What are the pressure readings that you have done.
What are your cold start pressure readings?
Post back what you have.
You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors.
I think each injector is on a separate driver on that one.
Check for pulse to all of them.
Also check the ground wire leads to the fuel pump sending unit on the frame, a bad ground will give you a weak fuel pressure and a dirty fuel filter also. Start with the simple and replace the fuel filter and check the fuel pressure at the shredder valve and keep me posted. Good luck and while your replacing the fuel filter, check the wire harness to the fuel pump sending unit.
