I'm having an issue with my 92 pickup. A few days ago I went to start my truck and ran for about 5 sec then shuts off. Try starting it a few more times and after about 3 or 4 tries it stayed running. Since then everytime I go to start it it will do this couple times like an old carbureted motorcycle on a cold day. I just thought maybe my fuel pump is going or maybe clogged fuel filter but today when I was driving I went to turn my heat on. This was fine until I flipped the blower fan to wide open my truck died out almost instantly and I had to pullover. than it did the ol' start up for 5 sec and die again. Only this time it didn't wantto stay running. I got so frustrated looking around my truck and engine bay trying to figure this out I had to just chill for a minute. After about 5 min I tried starting it again and it was fine. I tried flipping the heater to full blast again and it did the exact same thing. I ended driving to town anyway and went to the bank. when I went to start my truck back up it did the same thing it's bin doing. Running then shutting off only it seems like it's getting worse. I also have a high idle once it warms up(1300-1600 rpm) not sure if it's related. Does anyone have any idea what the heck is going on here? Could this all be from a bad fuel pump? I just don't understand the thing with the heater fan.. any help would be really appreciated as this is my DD. Btw im new here so heres a pic of my rig

 

Time to break out the Multi Meter

A low voltage condition can cause the hard starts .

It might be a battery issue or charging

It might be a cable connection issue or a poor connection any place allowing the ECU voltage to drop .

I think the threshold voltage is around 11VDC being a best guess

Thus why the blower motor turned on cause the ignition to shut off.

 

"Runs then shuts off" is the classic sign of a VAF-COR issue.

This is the easiest thing on your truck to test. Jumper FP to B+ on the diagnostic connector. If that eliminates the issue, you have an intermittent fault in the VAF, COR, or wiring in between.

I think the stuff with the heater fan is just a coincidence, but the above test will tell you.

 

Damn I was hoping it wasn't something electrical lol. Some guy who had this thing before me did some very "interesting" wiring around my engine bay so I better go check that out. What you said makes sense though. Gonna be a long night in the shed for me I guess haha. Thanks guys

 

I will try that thanks for the tip! I really don't think it's a coincidence because after the heater made it bog out the starting problem got much worse. Sounds like I've more than likely got a wiring problem which doesn't surprise me because I found a few connections done with merrets... I think I'll clean my throttle body too just in case but thanks for the tip on the vaf and cor I'm going to check that now