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Questions and Answers

Ford Bronco Loses Power And Stalls

Q. Hello Vince, I have a 1986 Ford Bronco V-8 with Fuel Injection. It runs fine until it heats up and then it loses power and shuts down and sometimes it shuts off. At first I thought that it was a fuel problem as though something was restricting the fuel flow. Years ago I had a 1957 Corvette that had a small twig in the gas tank and eventually the twig would work its way into the outlet tube of the gas tank and caused the car to shut down.

Ford Bronco Loses Power And Stalls

On the Ford Bronco I disconnected the two fuel lines on top of the gas tank and blew 120 psi of air into the fittings in case there was something clogging the filters. Then I emptied the plastic fuel filter on the frame located just under the drivers side door and replaced the metal fuel filter in front of the electric pump mounted on the frame.

As I am riding down the road and the engine looses power, if I put the auto trans in Neutral and race the engine it revs up but as soon as I put it in gear it has no power. Sometimes if I floor it has power until it peaks out and then it starts all over again.

If I turn the ignition off and leave it off for about 5-10 minutes it runs okay until it heats up again. I have replaced the ignition coil and the electric fuel pump relay.

Sometimes when I go around a corner it shuts off. Is there another relay for the injection unit that may be causing the problem?

Thanks,
Tom
New Jersey

A. The first things I would check are the Engine Coolant Temperature (ECT) sensor, fuel pressure and volume.

If the ECT is shorted out and telling the PCM the engine is running hotter than it actually is, the PCM will lean out the fuel mixture to the point where it would cause the problem you describe.

If fuel pump pressure is too low, or it's not putting out enough fuel for the engine to operate efficiently, you will have this problem as well.

In the 1985 to 1991 Ford Bronco, Econoline and F-Series trucks the fuel injectors were prone to lean fuel flow resulting from pintle deposit formation on non-deposit resistant fuel injectors. Injector cleaning usually doesn't fix the problem and the best fix is to replace the fuel injectors with Deposit Resistant Injectors (DRI'S) as replacements for non-deposit resistant injectors that exhibit lean fuel flow.

Have you checked the computer for stored codes yet?

Additional Information provided courtesy of AllDATA

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