daviddelki

Is there a way to test a fuel pump control on a Lexus 1994 LS400

oldskewel

iTrader: (1)

I'm not sure if the '94 is the exact same as the '91, but here is some info I posted for when I was troubleshooting my fuel system. For me, it was solved by replacing the fuel pump.

https://www.clublexus.com/forums/ls-...ml#post9777959

lextout

one of the symptoms i had was that the car would keep on cranking but wouldn't start.

daviddelki

I was wondering if i could take an OHM meter and test the fuel pump control and see if it was defective before i replace the actual pump.

oldskewel

iTrader: (1)

Yes, that is one of the tests I did. As explained in the post I linked above, you can even do this measurement at the fuel pump relay location in the engine bay. Easily accessible.

Another easy test is the one where you jumper the circuit to cause the fuel pump to run when the ignition is ON, even when you're not cranking or running the engine. With everything else silent, it is easy to hear the fuel flowing through the fuel rails on top of the engine, so that's a good test of a few things right there. Again, explained in my linked post.

In my case, I had a soft fuel pump failure, meaning it still pumped, just not as strong as it should be. So I did all those tests and did not find any confirmed problems. I then took a leap of faith to just replace the pump since it seemed nothing else could explain the driving problems I had. And that solved it.

A fuel pressure test would have been good to do, but I did not have the proper fitting.