Hey.

So my 99 blazer 4.3L won't start when it's getting hot. It starts almost all the time at home, but when i'm outside and kill it to then start up later it won't 50% of the time. If i fill it with fuel the car probably won't start, and i'd have to disconnect the + cable from the battery or jumpstart the fuelpump because the car isn't recieving fuel. The fuelpump can start, but sometimes won't pump fuel anyways. I have literally no idea of what to do, i've switched the fuelpump already, and it didn't help at all. Please help me!

Best regards

Ole J.

 

Kind of sounds like vapor lock, but that's not usually an issue with an F-I motor, assuming your starter is working okay. Could be and likely is an ignition issue. Have you
run any OBD II codes on it? Could even be the ignition switch. I'd check for spark. Might be a something with the PCM, the distributor (how are the cap and rotor looking?)

 

thought the idea behind priming the fuel system was to eliminate vapor lock?


TO OP
how do you know its not getting fuel?
how did you jump the pump?
like henry said about spark, have you checked for that?

 

I checked if it got fuel in the engine room, and there's usually no pressure.
I'm sorry, i meant that i primed it, not jump started it.
We recently switched the plugs, and we check with a scan tool everytime something happens if there is a problem with them.

It's really here and there, really har to tell. Most of the tips we get/find never helps the problem, and it's quite unpredictable.

 

so you can hear the pump "prime" but there wont be any pressure in the line?

 

Some of the time, yes. Sometimes it just doens't prime at all when i fill it with fuel or just kill it to start later.

 

it kinda sounds like maybe an pressure regulator ? You need to do a fuel press test and after your initial press relay run and pump cycle you should be around 55 to 60 psi and drop 5 psi after cycle then hold for a couple of minutes before slowely bleeding off ! If anything other id say fuel lines rusted or regulators the issue ! You have to keep chopping this away untill you find its problem.