98 s10 blazer runs and dies

[Billy J]

4.3L vortec , changed coil and module .truck runs for a while and dies what could cause this?once it warms up it will die after a few minutes.cold it runs until it warms up. not sure what to do..

[MT-2500]

Any check engine lights or flashing lights on?
Check for codes.
Post back any codes.
Check fuel pressure cold and hot and when it quits and post back readings.
When it quits check for lose of spark or lose of fuel pressure.
How many miles on tune up?

[Billy J]

no, there is no check engine light, I even unpluged a few sensors to make sure the light and the computer was working and it sets codes for them. I have no pressure gauge to check fuel pressure.. the fuel pump is very loud and when i press the fuel neddle valve on the fuel rail theres not much pressure. when it stops running the fuel pump is still running and not pressure on the rail valve.

[MT-2500]

How many miles on tune up?
How is the fuel filter?
It will not run without fuel prtssure.
Borrow or rent or buy a fuel pressure gauge.Some parts places loan or rent or sell them.
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 and fuel pressure testing guide line.
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.

[Billy J]

I changed the fuel pump $200. +.. all is well so for. Thanks for all the info. Keep up the good work.

[MT-2500]

You are welcome and thanks for posting back the fix.
Did the fuel pressure test show bad pump?
Good luck

[Billy J]

yes, fuel pressure was at 25lbs, Pluss the pump was real loud so that should of gave it away. The new pump is quiet.Thanks again, its always nice to get free help.

[MT-2500]

Originally Posted by Billy J

yes, fuel pressure was at 25lbs, Pluss the pump was real loud so that should of gave it away. The new pump is quiet.Thanks again, its always nice to get free help.

You are welcome