hello guys. here's my problem. i have a 1998 chevy blazer scfi 4.3L and my problem is when driving i the vehicle wil shut off for a split second and then comes back on automatically... so something like this when running ------o-------o------- .... its just so weird. i see the rpm drop to zero then as if magic the blazer comes back on. so for a while i thought it could be my new Delphi fuel pump that i just installed in february since it seemed to me to be a little louder now that i was having this problem. now when idleing it would do it also but it would just shutdown... so finally while driving one day to work it shut down. so i thought ok ill just start it up like always no problem. well this time it didnt start, so i had to tow it home. once home i removed the battery to charge it since it got low from trying to start it. came back a few hours later installed it and it started right up. so i decided to check the fuel pressure. 60 psi when key turned and 60 psi when running, didnt do a leakdown test but i will to rule that out. so as the vehicle was idleing and me looking the guage it shutdown again. it still held 60 psi the whole time and the guage didnt even move. so it safe to rule out a fuel problem cause its obviously getting fuel. what do you guys think? what should be the next thing to look at... im stumped on this one. btw also a new spider assembly, with new intake gaskets, and ignition module intalled with the pump.Thanks once again.

 

Does everything in the dash go dead? If so, I would be more inclined to think that the problem is with the ignition switch itself. Take a read/look at the thread linked to at the bottom of my signature below. You can test the wiring in/out of the ignition switch fairly easily with a multimeter and some time.

 

I just bought my 98 Blazer and it is having the same problems so Im thinking its the ignition switch. Though when I bought it the dealer said they had to cut a new key for it and it only works in one position. Just wondering if you think the key might be the problem before i drop a new switch in it.

 

No.

Assume you mean you have to insert key with a certain cut side up. If it turns freely it wont affect the switch. Whole different mechanism.

Locate ign switch itself and assoc wire harness.

Turn to 'run'.

thump and wiggle while watching dash lights.

 

This post actually reminded me of ignition switch work I had to do on my '95 Blazer a couple of years ago. I was having the same problems described. Took me a little bit to figure it out. I think I was somewhere at the frustration side (near the end) of my troubleshooting and I bumped the key ring with my arm. I saw a very faint flash on the dash, so I "jiggled" it around. Sure enough, I found the sweet spot. I can't remember exactly what I did, but I do remember taking the switch out to fix it. I think there was something either in the column or the switch that was worn and I had to do some minor fabricating. I'm sorry I wish I could remember what it was I fixed exactly, but I know I didn't buy anything. Fixed it with what I had in my garage. No problems since.

 

i believe you guys are on to something. after quickly scanning over wiring diagram of everything that the ignition switch controls, i noticed one of the pins calls out the "key reminder" and i always noticed that my key reminder would never really work except every few times a year would actually ring .. so either the switch is so worn out or burnt that its affecting other things. i will check it out this weekend and hopefully get this running soon. . ill check back to let you know how it went. thanks guys for your help

 

Alright ignition switch did not fix the problem. Im starting to think that its the ground somewhere. The clock on the radio keeps resetting so thats why im thinking its the ground. It seems to do it after it has sat for a while. Its almost like it has a carb with a bad choke and you can keep it running with the gas and the brake. Which was making me think it was a fuel problem but why is the clock resetting?