Here is the deal, I have a 2001 blazer 4x4, 4 door, 150,000 on it, last year it got a new fuel filter/pump. During the nice 60 degree thaw we had in Michigan a few weeks ago and humidity at 80% it decided over the weekend that when I got in on monday to got work- not to start. Last year it did the same thing when we had the mid-winter thaw and we thought because it does turn over maybe fuel pump and filter. After sitting most the winter in my garage,one warmer day after replacing only the filter I got in to just see if I could drive itand it started, I immediatly took it to go get the pump replaced. no problems since then except for this most recent thaw and not starting. We tried starting fluid and nothing. it turns over, I can hear the pump hum when I turn over but not on. I don't know what to do. I think my next guess would be plugs or the wires...I don't know. I bought it used and so I have no history of when they were last chaged. Additionally I firmly believe is has something to do with the humidity and moisture in the air.....any ideas would be GREAT. thanks

 

You first have to test the pressure to see if it really is a fuel delivery issue. You should see 55-60psi at the fuel pressure test port on the engine.

 

Moisture causing the problem would point to an ignition related failure. Grap a spare spark plug, ground it out against the motor, pull a plug wire, and see if ya get spark. If you do, next thing to test is injector pulse. Got that? Check fuel pressure. Got that? You are hallucinating, and it actually IS running.....[sm=icon_stickpoke.gif]

Where at in michigan? I am in adrian, and gots some tools, might be able to help.

 

what is the "injector pulse"?

 

Injector Pulse Width (IPW) is the amount of time the PCM holds the injector open for... I assume that is what you are asking about. If not, then the injector pulse would be the electronic signal telling the injector to open which is a square wave signal that shows voltage for the amount of time the PCM wants the injector to stay open. So for an IPW of 5ms, the voltage pulse would go from zero volts to the reference voltage level and remain at that level for 5ms.

 

Yep, I was referring to the electrical signal, but, now that I think about it, I do not know if there is a connector you can plug the noid lite into to test for injector pulse....

 

Not in the conventional sense, but if you remove the connector behind the throttle body, you can get the wires there. They are arranged nicely.

 

thanks I appreciate the help, we'll see what happens, seems a lot of guess and check...is there anything else we should be looking for in regards to moisture... being that it does this during a thaw like every year since I have had it... what about the distributer, cap/rotor...?

 

You can definitely pull the cap and have a look at the condition of the terminals inside as well as the center button. Check the rotor for carbon buildup on the tip.

But I would check for the presence of spark first.

 

It was the cap and rotor...it was very corroted. Got it replaced and had to jump it to start it up, drove it for 40-50miles to warm it up and charge, came home and tried to re-start it 5 hours later and no start so we are thinking that b/c of all the cranking and the cold weather that the starter has gone...any ideas...?
thanks for all the help!