Cars & Vehicles
Car Starting Problems
Fuel Pumps
Chevy Silverado
Ford Bronco II

I had to disconnect large wiring harness to replace VCGs. All wires reconnected but truck won't start. Will crank and spark but no fuel. Replaced hi-press fuel pump but same result. '88 2.9l Any ideas?

Answer

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09/12/2011

Thanks, J3h. The odd thing is, as you suggested, it was running fine prior to replacing the valve cover gaskets. I had to disconnect somewhere in the neighborhood of 10 different lines to free the harness to get the covers out and in. What really floored me is the fuel pump is the only thing that stopped working. Also, I tested the old pump and indeed it does work so I know that wasn't the issue. The multimeter testing had creeped up in the back of my mind, but I will try the disconnect/reconnect you suggested and see if that doesn't cure the problem first. I have a feeling if this gets to testing all points, it's going to take some time.

drcobol

Answer 1

IF everything was working properly PRIOR TO the disconnection of the harness connector(s), then it is probable that the problem is located within one of those connectors, OR a wire connection INTO one of those, or an adjacent connector. There are several possible explanations for the problem you describe.

First, I suspect that you replaced an expensive "hi-press fuel pump" when it probably was unnecessary. From the information in your question, it seems that everything is working EXCEPT the circuit [wire or a connection] which serves the fuel pump. Here is what I suggest you do.

1. Very carefully examine the subject connector, and other adjacent connectors to which its harness(s) run. Look for incompletely inserted connectors, or loose wires going into those connectors.

a. The actual metal contacts INSIDE the connectors could have been bent or damaged in the process of disconnection or reconnection.

b. Those metal contacts are generally "crimped" onto the end of their respective wires, and sometimes if the crimp was defective, it can easily be pulled apart when the connectors or harnesses are disturbed by disconnection, handling, or even movement.

2. IF step 1 does not reveal any explanation, then you need to, inch by inch, check the wire(s) running to the fuel pump. It is improbable, but possible, that a coincidental fault [probably an "open" circuit condition]occured "downstream."

3. If no visible faults can be observed, it will be necessary to begin TESTING at the fuel pump, and work back toward the battery.

a. First, make sure that the fuel pump is properly grounded. If there is a separate ground wire, disconnect it and make sure the contact area(s) are clean, bare metal. Then reconnect the ground.

b. With the connecter at the fuel pump disconnected, using a multi-meter, with the ignition switch ON, test the wire(s) in the connector for 12 volts DC. One or more of the wires should be "hot." If not, that suggests that the problem is a connection upstream, toward the battery.

c. Then, inch by inch, connector by connector, work your way back toward the battry. At some point, you should find 12 volt current. That point is where the fault is. It is also possible to do this check in reverse [FROM the battery], following the 12 volt current until it stops, again at the fault point.

Do not be surprized if the disconnection and reconnection of the connectors FIX the problem, without your even realizing you fixed it. Matter of fact, it may not hurt to try this first--the simple act of remaking of all connectors, from the battery to the fuel pump. j3h.