1994 s10 blazer.
cpi,map,iac,fuel pump, filter, plugs cap rotor wires .. all replaced, cat gutted, egr cleaned.

runs great now that all that is new. after driving for about 8 miles and it sits for about 2 hours it wont start. it cranks and nothing. the only thing i do ... dont know if its relevant but press in the schradder valve { spelling} a couple times and it starts.
i pump it once or twice, recycle the ignition. when it does start ... it fires fine, like nothing happened. short trips no problem. it takes at least an hour for the no start condition. it has had this issue for a while so i hear.

im wondering if the ignition switch ? i dont know. any help would b great. ty

 

Get a fuel pressure gauge and do the check. Also search on here for CPI INJECTOR and you will find all the info you will need to diagnose your problem. If you havent changed this part, then its due to be done. You may also want to get it running, and tug on the BLUE/RED wires that go into the intake behind and down from the EGR valve. You may just have a crappy connection on the injector harness - also a common problem. If you make the engine sputter or quit while messing with these wires, you have found the problem.

 

ty the cpi is new, lol, already had drama about that. i will give your suggestion a try. ty

 

Does any fuel come out when you press the schrader valve?

 

oh yes, plenty comes out. got spark. i can drive it 2 miles and it fires up again after sittin about 20 min. when i drive it at least 7 miles and let it sit for an hour it just cranks. the only thing i do .... again i dont know if its relevant .. i press the schrader valve and it fires up. sometimes i do it twice. this is after cranking it up at least 3 times.
when it starts, it starts like normal, not loaded up, no miss just like nothing happened.
i wonder if the ignition switch is failing. it had this issue before i got it. after everything else, i think im at the original problem now.
so what ever it is does it after it gets good and warm. i can drive round trip 5 miles and it will start as many times as i want it to no matter how long it sits.

 

Hmmm, these early CPI systems are going to have some kind of leak down rate. So the longer the truck sits not running the less static fuel pressure there is in the system. So on that idea, in the morning your truck has been sitting all night there should be zero fuel pressure. When you first turn the key to the "on" position the fuel pump is going to cycle to for a couple of seconds to prime the system. Then when you turn the key to the "start" position the computer pulses the maxi injector and the pump runs.

Try to see if it could be an issue with priming the fuel system. Click the key to the "on" position and listen for the fuel pump to run. You should hear it doing its thing from the back of the truck. If you can hear it cycle on for a few seconds then click the key back to the "off" position, wait a few seconds and click it back "on", try priming the fuel system a few times before you try to start the engine. If you find the engine will start after several priming attempts then I would suspect the check valve in the fuel pump. But you could always test the check valve at the pump by doing a leak down test at the line coming from the pump.

It could be the check valve at the pump is letting the static fuel to return to the tank and when you key on there is a vapor lock in the line so when you press the schrader valve it's priming the lines to the nut kit. That's the best I can up with, this is a strange problem and even stranger solution, pressing the schrader valve to start it. Just on a humor note, you could always attach a push button cable to the schrader valve and run it under your dash and have an anti-thief device.