Quote:
Originally Posted by nuckolls_7
I have a 98 blazer with the 4.3. It will start intermediately when it wants to. I have good fuel pressure and spark. I replace the fuel pump and fuel filter a year ago. And have checked the pressures today and they are still good. I have also replaced the plugs, put a reman distributor in it, cap, rotor, and ignition control module. There is plenty of spark but I cant figure out why it wont start. It will crank and fire but will not run. I did get it to run with starting fluid in it but as soon as I quite spraying it in it died. There are no codes to read either. I put the reman distributor in it and it ran for a week and a half with no problem. Now it is doing the same thing again. I am stumped and any help would be great.
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Go easy on starting fluid unless you want to blow the dip stick threw the hood.
Only use carb cleaner for starting aid.
If it starts with squirting in intake you have a fuel delivery problem.
You need 64-65 lbs of fuel pressure for injectors to squirt on a cold start.
Give us your fuel pressure readings.
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.