mclendon

datzenmike and lockleaf you guys are the BOSS. I found the problem. Someone had a jumper wire in the steering column running from one of the ignition wires to the red wire feeding the headlight switch. Disconnected jumper, connected the highlight power source from the battery and everything works as designed. I had to replace the fusible link at the battery. Why the hell would someone do that?! Thanks guys.

I traced the red wire from the battery. it goes to the headlights in the fuse panel. so the headlights are only coming on when the ignition is turned on. I must be getting some kind of back feed. when I plug the red wire up it is energizing the ignition fuses that is why the fuel pump is coming on. but it is only connected to the fuses for the headlights. and that is why my lights are coming on only when I turn the ignition on. it is back feeding from the ignition section of the fuse panel. is it possible that the fuse panel is shorted or is there some kind of relay I can look at. the red wire seems to run from the battery straight to the fuse panel. Thanks for all your help guys

datzenmike Seems I am wrong about the 2 sources to the fuel pump. Time for me to eat a little Crow it seems. I was told that the wire from the battery feed through the oil sending unit after the ruck was cranked.

There is a single red wire connected to the positive pole on the battery with a fuse link. Do you know what this feeds? I have 2 - 1985 trucks and both have this wire. One of the trucks doesn't run anymore but this red wire is plugged in on it. When I plug it up on the one I am referencing the fuel pup and air mixed in the carb comes on with the key off. Also can you tell me the way the fuel pump suppose to work. I know my original 1985 truck when you turned the key on the fuel pump would come on for a few seconds then go off. It did not come back on until you cranked the truck. At least I think that is the way it worked. At this point I am not really sure of anything anymore.

Not once have I ever said that there was constant power to the relay. There are defiantly 2 sources that find their way to the fuel pump. One originates at the fuse panel (which should stay on for a limited time) and the other at the battery (Which should come online after the truck is started). If I plug the one up at the battery the pump runs all the time even with the key out.

You are correct but the pump has 2 sources. Fuse box suppose to come on for a limited time to prime the carb. then the power source should come from the battery after the vehicle is cranked. In my description I described the problem I am having.

Yes datzenmike it is the 6 wire plug.

Yes It is the factory carb.

yes It is the factory carb

Hello everyone. I am new to the forum. 1985 Nissan 720 4X4 Z24 motor I have a problem with my fuel pump that I cannot get a grip on. I know that the fuel pump has 2 sources of power. I will refer to them as "Fuse block" and "Battery". The source from the Battery was unplugged when I got the truck. The reason is that when you plug it up the fuel pump comes on and the air mixer (don't know the proper name but you can hear it running in the front of the carburetor) in the carburetor comes on, this is with the truck tuned off and key out of the vehicle. So the battery supply must remain unplugged. That being said, the Fuse Block source runs the truck. It does not shut off. As long as the truck is turned on or cranked the fuel pump runs from this source. No time-out, it runs continuously. (Power from battery is unplugged) I have replaced the oil sending unit, The relay beside the battery, and the fuel pump module beside the blower motor inside the cab on the passenger side, Checked alternator voltage, Have found no evidence of any kind jumper wire that someone has installed. I would like to get this corrected because the air mixer in the carb. does not work. So until the truck warms up it runs too rich and causes to smoke a little. Any help would be greatly appreciated.