Hello,
I have a 1991 Bronco W/ 302 EFI, 4WD, and AOD. The truck started every once in a while shifting from overdrive to 3rd gear. Then one day I went to start the truck and it would not start. It would turn over but not fire, then it would finally start but would idle up and down and ran real rough with black smoke coming out the pipes. Went about a mile down the road then everything was fine till the next morning then the same thing again. The main thing I noticed is the fuel pump will stay on in the ON position without starting the truck where it would normally cut off in about 2 seconds and If the truck is running and you turn the ignition off one click the pump will stay on. I know a 311 code is Thermactor system problem. I have checked all Vac. lines to the air diverter and piping from the heads to the Cat. Also checked relays for fuel pump problem and they were OK. Wondering will a Thermactor problem cause starting problems and keep the fuel pump on or do I have some type of ECM problem. Any help would be appreciated.

 

pull the vacum line going to your fuel pressure regulator. if gas comes out that is your problem. the pump shouldnt stay running, so either the fpr is bad or you have some stuck injectors.

 

I checked the Vac on top of the regulator and it was dry. I also tested the fuel pressure and have good feul pressure going to the injectors. I am also getting fire but the bronco still will not start and the pump will still stay running. I also tried to put the code finder back on the truck and now it will not read any codes at all. The reader just stays on and won't read anything. I also noticed that if I the key turned on that I can not turn the overdrive switch to the off position which I noticed would also happen when the truck would not idle correctly. Is it possible to have a bad ecm because of the multiple problems I seem to be having and that the code reader will not read now but it did originally. Any Suggestions?

 

Double check your grounds. A loose or coroded ground wire may cause the odd erractic electrical symptoms you described.

 

I had the exact same problem.....I opened up the ecu and it looked like a box of fourth of july snakes were set off in it .....it was fried

 

Larry

Did you buy a new ECM, what did it cost to fix the problem?
Thanks

 

$130.00 at autozone

 

i heard you could run a lightning ecm inplace of oem 95bronco

 

I did fix my problem and forgot to repost. I did have to replace the ECM and it did fix my problem. I believe it was around $115 at advance auto after I returned the core. Truck has been running fine now for the last 2 months. I also found that I did have a plug off the thermactor.