Bronco fuel problem

Tiny
MEDICMAN
  • MEMBER
  • 1989 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
I have a 1989 ford bronco with a 302(5.8 litre) and the fuel pump that is underneath on the frame runs all the time. Even while the motor runs it keeps running and want shut off. I have replaced the fuel pressure regulator, fuel pump relay and it still runs all the time. And at the same time the motor is running extremely rich, fouls the plugs and blows black smoke while it runs. I dont know what to do next can you help? Both fuel pumps are also brand new.
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Sunday, March 6th, 2011 AT 3:00 PM

9 Replies

Tiny
KHLOW2008
  • EXPERT
When motor is running, the fuel pump has to be running to keep the pressure. If the fuel pump shuts off, the engine would stall.

When engine is running rich, it is more likely to be a control or sensor problem.

Is the Check Engine Light indicating and have you tried to retrieve for trouble codes?
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Sunday, March 6th, 2011 AT 3:14 PM
Tiny
MEDICMAN
  • MEMBER
The engine light is on and a mechanic hooked up a handheld machine but he said it wouldn't give any engine info. The fuel pump that is running is the one under the frame. The mechanic said that ti should shut off after it builds up so much pressure. But even if the vehicle is not running and you turn the ignition to the on position it will set there and run constantly. I thought that once the fuel pressure built up to a certain psi that the regulator would shut the pump off. However I dont know that much about them.
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Sunday, March 6th, 2011 AT 3:30 PM
Tiny
KHLOW2008
  • EXPERT
No, the fuel pump would continue to run as long as the engine is running. The fuel pressure regulator is the one controlling the pressure.

However the fuel pump should turn off after 2 or 3 seconds off when ignition is turned on without starting engine. If the fuel pump continues to run, the fault would most likely to be due to a faulty fuel pump relay or the ECU.

Yours is a pred-OBD-II model so not all hand-held code reader works on it. The followig link explains how to manually retrieve trouble codes for your model.
http://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

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Sunday, March 6th, 2011 AT 4:02 PM
Tiny
KHLOW2008
  • EXPERT
Check for restrictions to the fuel return hose. Was a reading of the fuel pressure made?
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Sunday, March 6th, 2011 AT 4:03 PM
Tiny
MEDICMAN
  • MEMBER
I havn't checked the fuel pump pressure. Both pumps are new and the regulator and fuel pump relay is new. If the ecm or ecu wichever it is went bad would it cause the motor to run extremely rich like it is, I mean its running really rich and blowing black smoke
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Sunday, March 6th, 2011 AT 4:10 PM
Tiny
CJ MEDEVAC
  • EXPERT
I REALLY WOULDA THOUGHT MR. FUEL PUMP WOULDA BEEN IN MR. FUEL TANK, IS THIS A AFTER-MARKET, ADD-ON ELECTRIC FUEL PUMP?

AS FAR AS THE CODES KHLow2008 NEEDED, CAN YOU GO TO AUTOZONE OR ADVANCE AUTO, MAYBE OTHERS, AND GET "CODED" FOR FREE. THEN RETURN TO KHLow2008, WITH CODES/ RESULTS. THE MEDIC
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Sunday, March 6th, 2011 AT 4:10 PM
Tiny
KHLOW2008
  • EXPERT
A faulty ECU, Engine Coolant Temperature sensor or MAF would result in a rich running condition. Thee are other possible causes as well.
So would a restricted return passage for fuel coming out of the fuel pressure regulator and bad injectors.

Your mechanic mentiond high fuel pressure, how did he come to the conclusion? Without a pressure reading, you started replacing components that have not been verified to be faulty. That is rather expensive.
Your mechanic mentiond high pressure
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Monday, March 7th, 2011 AT 5:31 PM
Tiny
MEDICMAN
  • MEMBER
What could also cause the oil temp gas and battery gage to not work also how could you fit it
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Monday, March 7th, 2011 AT 8:12 PM
Tiny
KHLOW2008
  • EXPERT
That could be due to a blown gauge fuse. Check the fuse and if it is good, test for power supply to it and you might have to remove the meter cluster to check.

A faulty ignition switch might result in that as well and might be the cause why you are not able to start.
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Monday, March 7th, 2011 AT 8:29 PM

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