no computer codes

dispatchrobb · Oct 14, 2011

'89 BII 2.9 5-spd. The check engine light is on, but when we try to pull the codes, none come out. Fuel pump runs continuously, when warm, about 80 percent of the time, making it run horribly. Idles around 1500 rpm. fuel regulator is good. New injectors.

Any suggestions?

Bronco_Chuck · Oct 14, 2011

Have you checked for vacuum leaks? My 89 did the same thing when I got it. (except for the CEL) Ended up being a crack in the brake booster vacuum line.

dispatchrobb · Oct 14, 2011

no leaks. I'm half tempted to rip this 2.9 out and put a 2.8 in without all this computer garbage. probably cheaper than a 302 swap for now at least.

dispatchrobb · Oct 15, 2011

Driving it today I can now hear a whistle, it goes down and goes away when I apply the gas, and comes back and goes up when I come off the gas, think that could be vaccum? I still have no idea why the fuel pump would run continuously with the key on before starting the engine, and continue to run, when it's warm only. Starts a little rough, have to crank it once a long time, like 4-5 seconds and no start, and the second time turning the key starts right up, but it idles steady and runs ok, it just appears to run rich, like it's just dumping fuel in the cylinders constantly, if driven for longer periods of time it starts running progressivly worse.

adsm08 · Oct 15, 2011

I'd say you def have a small vac leak of some sort.

As for your fuel pumps running, have you tried replacing the relay? It's a return type system, the pumps are gonna run, but they shouldn't always run full bore.

Also a vac leak can make it do all sorts of stupid stuff because the computer can't figure out the air/fuel ratio because it is getting two conflicting sets of data.

As for your assertion that the fuel pumps running too much and causing your issues, have you verified this? Have you actually checked your fuel pressures?

dispatchrobb · Oct 15, 2011

I have a pressure gauge attached to the fuel rail, and it's a pretty constant, 30-40 psi and after shutting off it will eventually go back to zero. Just guessing that it's running rich since the pump is always running, but it seems to run and idle ok. I had it at a service shop and since they couldn't get any codes, they basicly said they couldn't do anything, and he asked if the pump ran all the time like that like it wasn't supposed to do that, so I'm back to guessing. Even when it's warm it takes several seconds of cranking to get it to start, but seems to idle ok. I had driven it one time for about 3 hours, and it was like not very much power, I stopped for gas, and when I went to start it, it pumped out enough white smoke to look like it exploded, had to crank it a ton but once it started the smoke went away and ran, just not so much power. I'll continue to search for a leak.

adsm08 · Oct 15, 2011

dispatchrobb said:
I have a pressure gauge attached to the fuel rail, and it's a pretty constant, 30-40 psi and after shutting off it will eventually go back to zero. Just guessing that it's running rich since the pump is always running, but it seems to run and idle ok. I had it at a service shop and since they couldn't get any codes, they basicly said they couldn't do anything, and he asked if the pump ran all the time like that like it wasn't supposed to do that, so I'm back to guessing. Even when it's warm it takes several seconds of cranking to get it to start, but seems to idle ok. I had driven it one time for about 3 hours, and it was like not very much power, I stopped for gas, and when I went to start it, it pumped out enough white smoke to look like it exploded, had to crank it a ton but once it started the smoke went away and ran, just not so much power. I'll continue to search for a leak.

Ok, on a return type fuel system like you have the pump will run pretty much all the time, at or near full capacity. It should take hours or days for the pressure to bleed back to zero though. Faster than hours indicates an issue with the check valve in the pump.

What really concerns me is your white smoke. That is an indication of water (or more concerning and likely with a 2.9, coolant) in the combustion chamber. Do a compression check, 2.9s were known for cracking heads. Last one I saw that did that acted much like you describe.

dispatchrobb · Oct 26, 2011

Ok, it's taken me a bit to get this done. No vaccumn leaks, and took it to a garage and they did a compression/leak test and said all cyliders have good compression. The spark plugs are all coated black, so they figure its an iginition issue, so they're digging into that.
I did note theres no smoke normally out the pipe, no sweet smell when you turn the heater on, no bubbles in the radiator when running, no white goopy stuff at all on the filler cap. Still no codes, so still a mystery.

adsm08 · Oct 26, 2011

Bad O2 sensor, bad fuel pressure regulator, bad TFI or coil, or it may just need a tune up.

Sounds like it's running a bit rich or burning too cold and the plugs are now soot-fouled.

dispatchrobb · Nov 10, 2011

Final update. Had it in the local garage, and found a few things. The ground to the computer was very rusted and would seperate sometimes, so they fixed that. Found a small crack on a main vaccum line on the engine, so replaced that, and found the fuel pressure gauge was actually broken, so the pressure wasn't anywhere near what we thought the gauge read, so replaced the fuel pressure regulator, and replaced the temp sensor to the computer that was bad. It started right up on the first crank and purred like it should.

BUT THEN, I drove it about 30 miles and I started hearing the heater core bubble, so I pulled over and watched the steam and smoke start billowing out under the hood and watched as coolant blew out of my overflow tank like old faithful, and listened as the engine completely died. Never started again. So it's back in the garage getting the engine completely rebuilt.

adsm08 · Nov 10, 2011

Oh that sucks.

no computer codes

New Member

Member

New Member

New Member

Senior Master Grease Monkey

New Member

Senior Master Grease Monkey

New Member

Senior Master Grease Monkey

New Member

Senior Master Grease Monkey

Sponsored Ad

Sponsored Ad

Today's birthdays

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals