ZERO resistance at fuel pump fuse

[rgk]

Would anyone be able to tell me the proper resistance for an in-tank fuel pump installed in an 88 245?

The pump reads about 7.6 ohms, but the reading at the fuse panel, when the pump is plugged in and the fuse is removed, is ZERO. I unplug the pump and the resistance at the fuse reads no continuity.

Any ideas? I'm having some fuel pressure issues under load when the rear pump is plugged in. Unplug it and the car runs excellent, but stalls after a while, probably due to not being able to extract the fuel from the tank.

It's not the relay. The resistance at the fuse panel still reads zero when relay is unplugged.

Thanks!

[jimmy57]

You have an unplugged or cut wire. It should read the 7.6 plus maybe as much as another 1 ohm for circuit resistance. The in-tank pump should run when you supply 12v to one side of fuse holder w/fuse out and the main should run when you supply 12v to the other.

[rgk]

Jimmy,

Thanks for the response. Are you saying that a wire related to the in-tank pump is cut or disconnected, or could it be any wire on that circuit?

This fuse box is doing strange things. My panel says that fuses 4 and 6 run the in-tank and external pumps, respectively. However, even with both fuses out, I can hear both pumps running when the car is running. But they don't turn on when the switch is set to "ON", only once the car is cranked and running. When I remove the #4, the hazard lights do not work, and when I remove #6, the cabin lights and power locks don't work. However, the fuses for those items still do their job - when I remove the 'hazard' fuse, the hazard lights don't work.

Good grief!

[rgk]

I'm reading the following page: http://cleanflametrap.com/transferPump.htm

A little bit down, where it says "Sometimes new senders need diagnosis too." the text in the photo talks about the possibility of the suppressor choke causing an open circuit. Does anyone have any idea how I can test or replace this suppressor choke?

[rgk]

The text in the image states "This new sender has a defect where enamel was not removed from the suppressor choke either by abrasion or by the soldering process, resulting in an open circuit to the tank pump."

I am very curious what this means. How would enamel create an open circuit, and can I fix it by simply sanding it and applying some flux?

[jimmy57]

Where did you read the 7.6 ohms for in-tank pump?

[rgk]

At the pump terminals with the pump disconnected.

[jimmy57]

Remove the inspection cover that is below the forward cargo floor and measure pump there. If it is open circuit there then you're removing the pump and finding the problem. Otherwise it is further up the line.

[rgk]

I cleaned the connectors that sit on top of the pump terminals. That helped. I have proper resistance at the fuse, but my hesitation under load problem persists. Perhaps the pumps or filters are worn out. Perhaps I need to take care of the rest of my electrical woes.