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post #1 of 6 (permalink) Old 07-23-07, 01:50 PM Thread Starter
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Bronco II fuel system voes - please help

86 Bronco II, 2.9 V6, 4x4

Fuel pump won't 'buzz' when ignition is turned on. Trying to identify the reason as I hope it will be something simpler than having to replace the fuel pump from inside the tank, a job I couldn't do myself and one I understand doesn't come cheap. I suspect this to be a possible electrical problem, but you tell me.

This is a beautiful machine with a new engine and tons of new parts (6g invested). It was running like a new car before this problem. Then, after having it parked for the winter, it wouldn't start. I don't get any signs of life from the fuel pump, upon turning on the ignition key.

What I have done: played with the inertia switch, it did no good. Even held down the white button while turning the key on and nothing. Replaced the fuel pump relay, still nothing. So I went under the vehicle, located the 4 wires that go into the pump and tested for voltage (with a voltmeter) the yellow and the orange wires (didn't bother with the pink and I think the brown one for now). The orange wire showed no sign of life, which may be OK. The yellow wire I thought would be the positive and that it fed the pump with 12V. But upon testing it, the needle in the voltmeter was bouncing from zero to 5 or 6V, going up and down like a bouncing basket ball. Is this normal? Does this indicate a problem with some electrical part somewhere? Someone suggested it could be my voltage regulator but I should point out that all the lights in the Bronco work fine, from the headlights to the turn signal and interior stuff. Could still be the voltage regulator? Help with this long lasting problem appreciated.

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post #2 of 6 (permalink) Old 07-24-07, 04:42 AM
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Re: Bronco II fuel system voes - please help

Sounds like a ground problem to me. Check all grounds in the engine bay, battery terminals, earth strap that joins engine block to body, etc. If you have acces to a wiring diagram, see where the ground connector for the fuel pump is located and check it too. cheers

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post #3 of 6 (permalink) Old 07-24-07, 06:49 PM
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Re: Bronco II fuel system voes - please help

I'm with backlash1 on this one. A poor ground can cause problems. On some Fords, there is a small ground wire that comes from the battery post. If this becomes dis-connected, the fuel pump will not come on.
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post #4 of 6 (permalink) Old 03-04-09, 04:20 PM Thread Starter
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Re: Bronco II fuel system voes - please help


Here's a delayed update on the condition of the vehicle and the fix. It took this long as just recently I got the Bronco back from the shop, where it spent a whole year.

Basically the problem with the lack of ignition was due to faulty wiring. It was NOT the fuel pump, although I did have it replaced. I did check the wires on my own but couldn't see anything out of place, so I assumed it was the pump since it didn't buzz. Wrong. A few hundred dollars later the car still wouldn't start and had to be towed to a shop that knows their stuff. After investigating it was deemed that the problem was due to faulty wiring, possibly rotted due to lack of being driven for over a year - or merely the fact that this is something built by goddamn Ford. Why can't Ford use quality wiring like most other (non domestic) manufacturer? I was amazed to find out that all of this agony I went through (and huge costs) was due to Ford wanting to save a few pennies by installing sub par wiring in their vehicles. Unf**kingbelievable.

So for anyone with similar problems please don't spend time/money replacing your fuel pump. Instead have someone that KNOWS what they're doing investigate the wiring as proposed by the other members here. Or just tow it to a shop and save yourself the hassle and additional costs of guessing.

Now that this has been fixed and I have spent close to a grand since the wiring gave out on me, I get to drive the vehicle again, after more than 2 years (it's a second vehicle so it wasn't missed much). It drives great and I like it as a vehicle but unfortunately it is still a damn ford and therefore will be sold before something else silly gives up on me and costs me another small fortune.

I think this experience has more than scared me straight to follow my instincts and NEVER AGAIN BUY ANOTHER DOMESTIC VEHICLE!
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post #5 of 6 (permalink) Old 03-09-09, 07:52 AM
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Re: Bronco II fuel system voes - please help

We actually just finished expierencing this. We had a mobile guy come out and take a look and it was combination of these things.

The actuating rod was worn.
The in tank fuel pump was bad.
The battery was bad.
The RELAYS under the hood on the drivers side were bad and corroded.

After a new battery, ignition kill switch, new fuel pump, and 3 new relays it starts up perfectly and runs great!!
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post #6 of 6 (permalink) Old 08-15-09, 04:59 PM
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Re: Bronco II fuel system voes - please help

I had the same problem with my 89 full size. Has power to pumps,fuel,spark. The problem was the ground wire at the battery. thanks thefonz
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