Questions and Answers

Nissan Hardbody Won't Start Q. Dear Mr. Ciulla, Hi, my name is Jeffrey and I am 35 years old. I have worked on and tinkered with cars and other types gasoline engines since before I was ten years old so I can say I am very knowledgeable of cars, more so with G.M. products. Anyway, I have been trying to fix this women's Nissan truck for over a week now.

She called me one afternoon and tells me her truck won't start. So I drive over to where she is, stick my head under by the gas tank, tell her to turn the key on "Hmmm the pump's not running". So therefore I check fuses, relays look for any obvious wire damage, everything's okay. (I hope that you don't mind this long explanation. Just trying to give you a picture of what I have done.) We have the truck towed to her sisters home so I can install a new fuel pump. Put in new pump and get everything hooked back up, turn the key, nothing pump still not working.

I decide to drop the tank again and remove the pump to make sure I didn't mess up. Even ran jumper wires to the pump. The pump does work. So now I'm checking wires fuses, relays, checking continuity and voltage with an analog meter. Run a self diagnostic on the ECU the only code that came up was 41. (air cleaner had been removed) Replace the ECU with different one. Still nothing.

A couple guys at the parts store said it was the ignition relay at the fuse panel. Replaced it with a new one. Still the pump is not working. Check fuses again. Fuse is blown. Evidently I blew it testing the circuit. Replace fuse, crank engine, BOOM fires right up without a hitch. Let it run for 15 mins to get any air out that might be in the system. Let's make sure it will start again after we shut it off. Crank the engine won't start, pump fails to come on again. Oh yeah, I even disconnected the fuel filter on the pump side just to make sure the pump wasn't working.

I figure there is something telling the ECU to keep the fuel pump shut off. Can you please tell me what the possible causes are? It is a 1995 Nissan Ext. Cab pick up, KA24E multi point fuel injected engine, 5 speed manual transmission, it does have A/C. It does not have, cruise control, power doors, power windows or power seats.

Thank you for your time and patience.

Sincerely,
Jeffrey

A. The fuel pump circuit is a very simple one on that truck. You have power going to the relay and then to the pump. There is power to the relay coil and is grounded by the ECU as long as it sees the engine running.

Power to the relay comes directly from the fuse box via the black/white wire. Power goes to the fuel pump through the white/blue wire and to the ECU through the white/red wire. If you supply 12 volts to the white/blue wire and the pump doesn't run, you have a broken wire between the relay and the pump.

If it does run, ground the white/red wire and the pump should run. If it doesn't then you have a broken wire between the relay and the ECU.

One thing to check is the ground wire at the fuel pump. They do have a tendency to lose connection which would keep the pump from running. Hook up your test light to the white/blue wire at the fuel pump connector. If it lights up when you crank the engine, you lost ground.

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