Reference: 1992 Suzuki Carry DC51T I know issues with the fuel pump relay has been discussed before. I know the relay turns on the fuel pump for a few seconds when the key is turned on and then it will stop. My question is what turns the fuel pump back on and keeps it running once the engine is running? My fuel pump relay clicks when I turn the key, I hear the fuel pump run then stop after few seconds, the truck starts but the fuel pump will not turn back on and the engine will sputter and die after a few seconds. So what turns the fuel pump back on when the engine is running?
Theres another circuit tied into the coil that controls the pump running after starting. If that signal is not getting through it will not run after startup. Also the OEM pumps supposedly only run when they detect lower pressure even while running with the coil signal working.
Can you tell me more about this secondary circuit associated with the coil? How can I find and test this circuit?
I wish I had the answer for you, but I don't. I'm interested to see what the answer is. Mine works fine. I fear the day that I turn the key and don't hear that familiar hum of the fuel pump relay humming. Let us know what you find out. Kevin in NC
You have to dig into the electrical diagrams (which suck BTW) to figure it all out. The best solution is a 2 wire pump and a regulator, you might be able to skip the regulator depending on the pump you go with.
My fuel pump is a 2 wire pump. My problem is once the truck starts it no longer have power to the pump, only the first few seconds when I turn the key. Something is turning off the power to the pump. Unfortunately I do not have the electrical diagram. I have researched but cannot find a copy.
Verify that the power is actually being shut off to the pump when the key is in run after starting. If theres still power to the pump, then its a pump issue. Otherwise trace the wires back to where they come from. Its an older truck (1992) so not sure if this was originally 3 wire or a 2 wire pump.
I have a volt meter hooked up and it shows 12+ volt when the key is turned on and 0 volts after the truck starts. Obviously it dies after because there is no fuel to the carb. I am pretty sure it is a 2 wire pump since the wire harness has not been cut and only has a 2 wire connection.
Right. Isn't that the fuel pump relay? I know mine clicks when I turn the key, the fuel pump turns on for a few seconds then turns off. Didn't you say there's another circuit controlled by the coil that turns the fuel pump back on?
Pretty sure theres another relay involved. Its a safety thing so the pump doesn't run of it can't detect the engine running.
