98 Blazer Intermediate Starting

[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.

[MT-2500]

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.

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.

[nuckolls_7]

fuel pressure when the pump is running is about 62 or 63. when pump shuts off it drops to around 55 before cranking the truck. pressures are the same weather it starts or dose not. at idel it is alos around 63. i can't test it after a drive because it will not start now. i did check it befor to get the idle reading though.

[MT-2500]

Originally Posted by nuckolls_7

fuel pressure when the pump is running is about 62 or 63. when pump shuts off it drops to around 55 before cranking the truck. pressures are the same weather it starts or dose not. at idel it is alos around 63. i can't test it after a drive because it will not start now. i did check it befor to get the idle reading though.

Check for codes.
If you can get it on a scanner see it it has rpm signal.
Crank sensor has to run rpm signal for injectors to squirt.
Also check fuses and for 12 volt power to injectors.
Check for good hot spark to all plugs.
Post back any code no.

[nuckolls_7]

there is no code pressent
fuses are all good
shows rpm on the dash. dont know if thats whart u ment or not?

[nuckolls_7]

i have taken my blazer to the dealer now and they told me i had 4 stuck injectores. i had them clean them becaause they wanted over $1200 to replace them all. it ran for about a week and then not started again. i decided to put injectors in it now scince the dealer said cleaning them may only be a temp fix. it has now not started agin on my since. has anyone had this problem befor or know what step to take next to dignose this problem.

[MT-2500]

Originally Posted by nuckolls_7

i have taken my blazer to the dealer now and they told me i had 4 stuck injectores. i had them clean them becaause they wanted over $1200 to replace them all. it ran for about a week and then not started again. i decided to put injectors in it now scince the dealer said cleaning them may only be a temp fix. it has now not started agin on my since. has anyone had this problem befor or know what step to take next to dignose this problem.

Where are yo at on it now?
Have you replaced the injectors?
Does engine crank over good?
Does it have good spark when cranking?
Is fuel pressure still holding good?

If you have good spark and fuel pressure pull spark plugs and see if they are wet or dry on end.
Check compression when plugs are out.
If good compression and.
If plugs are wet or black on ends put a new set of AC delco plugs in it

[MT-2500]

I have never saw 4 injectors go bad at one time.

[nuckolls_7]

yes i did put all new injectors in the truck. I have already put new ac delco plugs in it. fuel pressure is still good and the same and the spark is also good in all cylinders. it has only had the problem once again scince i put the injectores in but dont want to risk it.

[MT-2500]

Originally Posted by nuckolls_7

yes i did put all new injectors in the truck. I have already put new ac delco plugs in it. fuel pressure is still good and the same and the spark is also good in all cylinders. it has only had the problem once again scince i put the injectores in but dont want to risk it.

You mean it has only failed to start one time since injector replacement.

See if it will start with a shot of carb cleaner when it acts up.

Pull some plugs and see if they are wet or dry on end.
Confirm good fuel pressure when it acts up.

keep us posted on how it goes.

[nuckolls_7]

it just decided to do it again today. it now has new injectors in it and good fuel pressure. it will run with carb cleaner but only as you spray it in as soon as you stop the truck dies. there is good spark and the plugs are dry when you pull them out. i am thinking it may be and injector pulse problem or a security problem. what do you guys think and is there any way to test them.

[MT-2500]

Originally Posted by nuckolls_7

it just decided to do it again today. it now has new injectors in it and good fuel pressure. it will run with carb cleaner but only as you spray it in as soon as you stop the truck dies. there is good spark and the plugs are dry when you pull them out. i am thinking it may be and injector pulse problem or a security problem. what do you guys think and is there any way to test them.

You need to test when it is doing it.
Check when it does it check for loss of spark and fuel pressure.
comfirm fuel pressure is at or near full specs.

Starts on carb cleaner points to fuel delivery problems.

A engine capable scanner or a injector testing noid light will confirm injector pulse.

Does security light come on for a bulb check and then go out or does it stay on?
Andy codes or check engine lights?

[nuckolls_7]

it has good spark and fuel pressure at all times. it will fire on carb cleaner but not run. the security light comes on when you turn on the key like normal then goes out. when you crank the key over it will come back on thenn go out.

[MT-2500]

Originally Posted by nuckolls_7

it has good spark and fuel pressure at all times. it will fire on carb cleaner but not run. the security light comes on when you turn on the key like normal then goes out. when you crank the key over it will come back on thenn go out.

Fuel pressure at 64-65 lbs cranking?
Any aftermarket alarms or remote start systems?
Doe security light come on cranking ?
If it fires on carb cleaner you have a fuel delivery problem.
Fuel pressure or lose of injector pulse.
Check for injector pulse when cranking engine.

Give it the old key on 3 times for 10 minutes again.
Will security light come on and go off each time?

Recheck for codes with a good engine capable scanner.

[nuckolls_7]

i went out this morning and it finally started again. i let if run for a few minutes and when i came back the security light was on. i drove it for about 30 or 40 minutes and it didn't go off. is this a sign of a security problem?