I'm sure this question has been addressed before, I can't find the answer by doing a search. This is my Bronco's vitals. 1992 Full size Bronco, 302 / 5.0
A4OD, A/C.

When I turn the key to the on position (not start), the fuel pump keeps running, won't prime. It won't start, or may start and runs extremely rough and smokes black smoke. It's not driveable during this rough idling. You can put the truck in gear and it will barely move even with the thottle all most floored.

If I get it started, the check engine light is always on while it's running rough. If the check engine light goes out while idling, the engine suddenly runs perfect. If I shut off the engine and try a restart it will run perfect if the check engine light does not come. The fuel pump will prime as long as the check engine is not on. If I turn the key to the on position and the check engine light comes on (fuel pump won't prime), it's hard to start and it runs rough and smokes.

I've tried to read the codes but get eradic readings. I get codes for EGR, and O2 overheat. No fuel present when I remove the vacuum hose from the fuel pressure regulator. I have not checked the fuel pressure, because it runs perfect if the check engine light is not on.

Please Help

 

i would replace the fuel pressure regulator. if that doesnt fix the problem then you have an injector that is stuck open. check the oil for the pressence of fuel as well. if you pull the plugs which ever has the most fuel would probably indicate which injector is bad.

 

Kemicalburns,
Thanks for the quick response. I'll try the regulator first and let you know the outcome.

Also, in a previous post you stated you purchased a Fuel Pump for your 94 Bronco for $120.00 with the fuel level float. I can't find a Ford brand fuel pump in Texas for less than $289.00. Where did you find the pump?

Sweed

 

actually it was for my 88 bronco, i would imagine they are the same. i think i spent more round 140-160 now that i think about it. but it was definatly cheaper then what your stating. have you called ford or are you asking different parts stores

 

If your fuel pump won't stop running it's because it's cycling the fuel from the tank out to the engine and then back without the fuel regulator stopping it. A fuel pressure tester can verify this for you for about $30. The Haynes and Chiltons manuals both have the run, stop and start pressures for the fuel rail. Usually when the pump stops working it doesn't run. Period.

The other one is that your relay is stuck but if it shuts off when the key is off - then its not this one.

Hope it's the cheaper fix.

Woodler

 

I replaced the fuel pump about 5 years ago. I'm hoping this problem is only a fuel pressure regulator and not an injector problem. I meant to replace the regulator last night, but my house septic system put a stop to that idea so I had to change my plans. My Bronco is not a daily driver, however, the septic system is a Daily use item so it has priority.

Thanks again for everyone's help. This is a great site to get the right answers.

 

Did you ever find out the problem? My 96 F150 is doing the exact same thing.

 

SpoolingV8
I sold the Bronco in July. The new owner replaced the main computer and the Bronco runs better than when I owned it.

Sweed