Bronco II fuel system voes - please help - Ford Forums

CosworthF1 · 07-23-2007, 13:50

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.

backlash1 · 07-24-2007, 04:42

Hi
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

marc

thefonz · 07-24-2007, 18:49

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.