trying to fix Jr's truck as it doesnt want to run right... when the we got it, it ran perfect. Sat for a month or so then fired it up and it ran like crap. took it fora spin and it acted just like a bad fuel pump, surging as if it was starving for fuel. So here's what we've done to it...

new fuel filter,

checked fuel pressure under load...( in gear with some throttle) sits at 12.5 psi, range is 9-13psi.

take a peek at the injectors and the appear to be working.

checked all the vacuum lines for leaks, none.

then I went to set the timing and yank the connector that i'm instructed to and fire it back up and it purrs like a kitten, idles perfectly. verify the timing and it's good, plug the timing wire back in and runs like crap again. so I think the ignition module might be bad and swap it out... nope, same problem.

Now i'm thinking it could be a ECM (PCM) problem or one of the inputs to it. As of now there are no CE lights and I have not checked it for any codes yet (just found out how last night).

So has anyone here run into this on a Chevy 350 before? year is 1991 1/2 ton truck, TBI motor

 

There's no water in the fuel is there?
Distributor ok, does this one have a vacuum advance?

 

Not trying to be funny but did you check to see if anything made a nest in the air intake system? or Throttle body?

My uncles truck sat outside his garage for 3 weeks and mice clogged his air intake with a nest.

 

nope, no water & no nests... air filter is off, injector squirts... runs great with the timing wire disconnected... meaning it's in open loop mode, ignoring all the sensors.

 

Its gotta be a problem like you say, a used computer for 350 TBI's aren't to expensive. But still I pain since your not sure if that'll fix it. Hm

 

we have a 4x4 trip tomorrow with a bunch of locals & semi locals... Sunday we're doing a suspension test with 3 others (we're the photographers, Jr & I) so we wont get back to it on Monday. the plan will be to ohm out the sensor wires back to the computer to see if all of the inputs are making it back... if all that checks out then we'll look into a replacement comp.

 

Steve, I have no such ability to give you any help. I've read the plenum gasket guide step by step a million times. I was under the impression that you wrote it. Is this true? I saw on your cardomain the 2000 QC Ram, but now you're driving the CTD? Nice to have a guru stick around with us and help everyone. Good luck with the Chevrolet. I like those TBI motors. Never heard of one running like this.

 

Yup, I was formerly known as steve00ram360... thought it was easier to switch the year in my name herethan anything else. I also use it on every forum I go to...

last year I decided to sell the M3 & 2000 ram and get into 1 truck, so needing the space for the kids the larger quad cab was the better choice. The diesel has been a choice I have not regretted.. love it

 

yah steve ditched us about a year ago nahh just messin with ya steve

 

lol, hell no, I'm looking for a Jeep grand cherokee v8 to play with right now... would like to find one with a blown motor cheep. I can get another complete motor for about $175 bux, slap it in and build it as an on/off road toy...