I have a 1995 GMC Jimmy with the 4.3 Vin W and the lovely OBDII port with the OBD 1 operating system that I bought about a week ago. Of course it was fine when I looked at it and drove it home. A few days later I went to start it when the engine was cold and had to crank it a few times (2 or 3) for about 3-5 seconds each before it would start. A few days later same thing except I had to crank it 5 or 6 times for 3-5 secs each before it would start and that's how it's been ever since. It usually turns over a few times by itself but still fails to start. So far it always starts eventually and starts right up anytime after the 1st time. Runs good after it starts- no missing or anything. So far I've checked fuel pressure- 58 lbs with the key on; replaced fuel filter, replaced spark plugs, cap and rotor, and checked ignition module and it was good. Sometimes after driving it 10 miles or so at highway speeds the service engine soon light will come on. I attempted to scan it with a friend's scanner that reads OBD I & II but it requires a special $52 cable which I don't have the coin for right now. O- 1 more thing- on top of the engine near where the air intake goes into the plenum there is a little plastic box that goes into a sensor. On the box there is a red light and a green light. I can't find anywhere what this is. Repair manual doesn't say anything about it. Does anybody have an idea? The red light is on whenever the engine is running. Sorry for the long post but I just want to be as specific as possible. Any help would be greatly appreciated.

 

No idea on that addon box...

Did your fuel pressure drop at all after the pump shut off?

 

I kept an eye on it for a few minutes and it hadn't dropped off a significant amount. How could I test the spider to see if it's working properly? If I took a pic of the box instead of my wonderful description would that help? I have no idea what it is but there's a red light and a green light on it and the red one turns on- would make me think red is stop and green is go lol.

 

That box definetly sounds aftermarket,if you snap a pic we might be able to figure out what it is and why its there

 

ok here's a pic of the box- it looks like it just snaps in between the original connectors.
Shot with uD600,S600 at 2009-08-26

I took off the round black unit on top of the plenum (under the plastic Vortec cover) and looked inside and didn't see any washing. I turned the key on and off a few times and there was fuel inside of it- it looked moist all over inside of it. I'm going to pull off the plenum and see what I can find. Thanks.

 

That box looks like it is some sort of trigger for something else as it is connected to the TPS sensor... If you do not know what it triggers, I would try disconnecting it and reconnecting the factory harness to the TPS sensor and see what happens.

If there is fuel leaking, you should be able to see it when you remove the upper plenum.

 

Ok-pulled the upper plenum and then turned the key on and off a few times to try and see where it was leaking fuel. I couldn't see it leaking fuel but the pass side is cleaner than the driver's side so I'll go with pressure regulator. There is a small amount of fuel puddled on both sides. I wanted to replace the gas lines also but have to wait on it to come in. Here's a pic...


Shot with uD600,S600 at 2009-08-26

 

That does not look bad to me...

 

Would I be able to find where it's leaking fuel turning they key on and off letting the pump cycle? I still have 58 lbs of pressure with the key on. After turning the key off I lost 7 lbs of pressure in 10 minutes and 13 lbs of pressure in 20 minutes. If something in the plenum is not leaking why would there be a few small puddles of fuel in the bottom? Should I just replace the whole thing? If more than likely it is the CPI unit itself I'd rather go ahead and get it done while it's already apart. I looked in the repair manual and I've checked just about everything on their troubleshooting list (which is less comprehensive than what I can find on this site!) and I know I've got spark, so it has to be fuel related right? Thanks for the help.

 

Hey guys. Just wanted to let ya know I went ahead and replaced the pressure regulator with a new one and so far so good. Starts right up and runs good. Hopefully the ol CPI system will stay kickin for a while lol