Back to the drawing board...I've been working on a 1990 S10 Blazer, 4.3L TBI, 2WD, 5 speed that belongs to my son. About a month ago it began to sputter a little every once in a while but he just ignored it. Well, last week it cut out on him going down the road. Now, it will crank and run when parked. It won't idle for the first few minutes...you have to feather the gas to keep it running at first. Engine revs up without any hesitation as long as it's parked. When you try to drive it, it spits, sputters, and starts jerking like crazy. I haven't been able to get past 2nd gear. The only way to keep it cranked under load is to feather the gas, and it still runs horribly then - any time you push the accelerator down, it feels kinda like trying to ride a mechanical bull.

It had thrown codes on the coolant temp sensor and was showing a lean condition. So far I've tried removing the catalytic converter, new O2 sensor, new coolant temp sensor, replaced egr valve, cleaned pcv valve, replaced throttle position sensor, replaced coil, replaced ingnition control module, checked vaccuum lines, new fuel filter, and replaced intake gaskets (did find a leak on rear passenger side - reset timing after replacing gaskets). Nothing's helped so far. I'm thinking I need to check the fuel pressure...maybe pump or regulator's going bad. Any suggestions?

 

Changed the fuel pump and it fixed the problem. I don't think it was the fuel pump itself that was bad, but the little piece of hose that goes from the top of the pump to the assembly - it had a slit in it like it had busted. At any rate fuel pressure is back up and it's running like a champ again.