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I have a 1990 BII with the stock 2.9L w/5-speed. It started acting up so i checked dtcs and found a map sensor code. Replaced the sensor and the same problem remains, code went away though. i ck fuel pressure and it had 16psi(should be at least 30). checked the regulator, its ok. replaced the fuel pump, got 35 psi now, still runs like absolute crap. Usually if you slowly ease into it it'll be alright, but not always, you can never open it up or it won't rev at all, just stay around 1100-1300 rpms, some times backfiring through the intake. It has absolutly no power in the lower rpms trying to start off, once it gets moving it does slightly better, but not good enough for OD, and it cuts out almost like I let off the gas and then floored it. it can't maintain 40mph in third up a average hill. I have run the KOEO and KOER tests several times with system pass. Please help its my primary transportation.

change your fuel filter. sounds like its not getting enough fuel. even though it has pressure it may not have the volume flowing to supply the engine. by you replacing the pump indicated fuel restriction. if the filter does not fix it pull the sending unit and make sure its not clogged. it has a filter screen on the pick up

Thanks for the reply. I replaced the fuel filter about two or three weeks ago, I just had the fuel tank out for the fuel pump, i replaced the little pickup sock at the same time. I checked around the inside of the tank while the sending unit was out, very clean. I have checked fuel flow with the pressure gage release valve, seams to flow plenty. I'm not sure if all BIIs are the same but the 90 model has a reserve tank the fuel pump sits in, and the sock goes on the bottom of the tank, not the pump it self.

well hell, thought it may be simple. with no codes its either fuel (which you already eliminated) or spark. possibly coil, or tfi, or ditributor pick up. can you feel the exhaust flow from the tail pipe with adequate pressure?

Ok I replaced the coil and it got just a little better, so i tryed moving the timing and it runs much better and has more power with the timing advanced. but only if i advance it to the point its hard to crank and pings like crazy. I don't believe the timing is advancing like it should. What controls spark advance and how?

first I would set the timing to the factory setting with a timing light and see what you get.
if it doesn't fix the problem then pull you ign. mod off the side of the distributor and take it to auto zone to have it checked. have them check it a few times because it doesn't always read bad the first time.

sounds like your going in the right direction. only thing i would add to dbrowns advice is if the tfi checks good replace the distributor pick up module, or the distributor, which ever is easier or cheaper for you

Again thanks for the reply, and again, already replaced the module and pickup about a month ago cause it died with no attempt to start again.
I'm beginning to think the timing chain is worn and the engine has jumped time, cause its the only thing that could really make it run better with the distributer turned so far from where it ran perfectly just a week ago.

already replaced the module and pickup about a month ago cause it died with no attempt to start again.

at no point in your previous posts did you say you replaced the mod. on the side of the distibutor...

What controls spark advance and how?

that mod. is what controls the timing

did you check the plugs to see what they looked like?

Didn't think about it, it was when i first got it running. Checked the plugs, they look fine. I'm starting to think the timing chain is worn and it jumped time. I'm planning on checking on that this evening.

did you ever get this fixed ?

Not yet, I checked the timing chain, perfect. and I pulled the distributer to see if the gear was messed, up, but it was fine. I'm completely stumped on this one. I'm about ready to junk it.

If the catalytic converters were restricted, but not completely plugged up, would changing the ignition timing make any difference in how it runs?????
I wouldn't think so

Godzilla9992 wrote:If the catalytic converters were restricted, but not completely plugged up, would changing the ignition timing make any difference in how it runs?????
I wouldn't think so

im thinking that a cat clogged would make it run like crap, no matter what you do to the engine or timing. glad i went to the 5.0l when i hear all the problems everyone has with the stock engine !!!!

Ok i have removed the catalytic converters, no change, replaced the throttle position sensor, no change. Please give me some more suggestions, my truck has set for almost two months now, very depressing.