well add another one to the books..... now it's running fine...???....??? dunno what I did, but it's runnin good with no lights..... maybe the truck was just testing me....???

 

well I had posted that my truck was running good..... that was only for 10 min and now it's a no start again...
1993 GMC Jimmy 4.3 CPI
ran good , but started acting like it was out of fuel again.... now no start.... checked fuel pressure and I have 60+ psi while cranking and with the key on..... maybe it's not a fuel problem....
is there a way to test the coil?.... I did the "screwdriver trick" and saw a spark, but could it be weak?
just looking for some direction to see what to check next..... don't wanna spend $200 to have it checked out.
also showing EGR and IAC trouble codes..... any help appreciated.

 

replace those sensors that could be the issue right there thats my suggestion unless someone else has a better idea

 

I would definitely try replacing the sensors. If that does not work you may very well have to send this to a professional and have them diagnose what is going on with it.

Although I think that the sensors are a good bet since those are the same codes that it keeps throwing out.

 

well today it ran good to go around the block twice then started acting up.... I checked the codes again and it gave me 33 & 35.... MAP sensor and IAC sensor...... wonder if I counted wrong the first time.... is there a way to test the map sensor? would it make it act funny?

 

A map sensor can be checked with a multimeter. A Haynes or Chiltons manual can tell you how to check it.
Another remote possibility could be vapor lock caused by the fuel line being too close to a hot engine part such as exhaust. It is uncommon with fuel injected engines, though.

 

It really sounds like your egr sensor. I was having problems with rough idle and stalling and finally after much testing I came up with this sensor and replaced it and it ran like a champ again. Never had this problem again.

 

Just jumping in here............. If the port in the manifold is clogged.....sludge and stuff..........the engine will stumble and run rough and maybe not run. Same symtom as a bad egr but just no port for the exhaust gas to travel through........I have a 350 TBI and actually keep a spare intake manifold and swap it out every couple of years. JMHO!
Dont leave any stones unturned!

 

well now for another code.... I'm getting 33,34, & 35 now.....no 32but the truck seems to be running great, no hard idling, no stalling....... I can't take it to the shop unless it's running bad.... I think I'll try to replace the MAP and the IAC.... really confused, I drove it about 5 miles today and it ran great. I can't trust it to go any farther than that.

 

MAP sensors can be kinda pricey. One for my '91 is about $50. So I would probably try to test it first. The auto parts store may also be able to test some of your sensors for you for no charge.
Just a thought b4 you replace expensive sensors that are still good.