97 4.3 won't start.

[Mike7468]

last week wouldn't start. ended up replacing spark plugs, it started ran for a few days then sunday it didn't start again. pulled the plugs seems like there is a lot of gas on the plugs. It is as if there isn't any spark going, I replaced the coolant temp. sensor yesterday still same result. when i pulled the wire off the plug there was spark. any ideas??

[tblake]

Could the plugs be fouling out with too much gas?

Mine started missfiring one day on my way home from work. Ended up being a fuel pressure regulator dumping all 60psi of fuel pressure into one cylinders intake runner. Fuel pressure would pump up to about 60psi and then drop to 0 within seconds. New FPR fixed the problem.

[Mike7468]

Pretty sure they where fouling out due to, too much gas I am trying to find out why it is getting to much gas. I did fail to mention It sat for 24 hours before I replaced the Coolant Temp. Sensor, and DID NOT pull the plugs out and dry them.. Should I attempt that before I sink money into another part? I last tried to start it at about 8 pm last night and won't have another chance till maybe 6 tonite? Should I pull the plugs and dry them or should enough time have passed to where they should have dried out enough??

[MT-2500]

Originally Posted by Mike7468

Pretty sure they where fouling out due to, too much gas I am trying to find out why it is getting to much gas. I did fail to mention It sat for 24 hours before I replaced the Coolant Temp. Sensor, and DID NOT pull the plugs out and dry them.. Should I attempt that before I sink money into another part? I last tried to start it at about 8 pm last night and won't have another chance till maybe 6 tonite? Should I pull the plugs and dry them or should enough time have passed to where they should have dried out enough??

Drying off may help get it started.
If pluges are gas fouled with black stuff some times yoou have to replace them.

I would run a fuel pressure test on it and watch for fast leak down.
Also chek for lose of spark to plugs when no start.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
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.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding 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.
Do not leave home without it.
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 in system.
Post back fuel pressure readings.