Fp Ecu Bypass Problem

[tpnotch420]

okay I have a 92 SC400 that won't start so after doing some research I thought I would troubleshoot the fuel system. When I turn the key on I can't hear the fuel pump running so I decided to try the FP ECU bypass to see if it's the pump or the ecu that is causing the problems. Now when I turn the key on I hear the fuel pump running, but when I turn it off the pump will continue to run until I either disconnect the battery or remove the EFI relay. I'm pretty sure the system isn't suppose to work like this.

Does anyone have any idea what could be causing this? Is it likely to be the engine ECU

[tpnotch420]

would this likely be a fuel pressure problem or an electrical problem?

if electrical is the likely culprit a grounded wire, bad sensor or a bad engine ecu

if it's the ecu is there a diy test for the ecu or do I just need to replace it and see what happens?

[UCF3]

I'm thinking it's an electrical issue, but can't really tell you exactly what it is. Take the EFI relay off, and troubleshoot by engine electricals. Give us some more details on the start-up.

Is this a recent occurance?

when you're in ACC-mode and turn, does it click, display has everything lit up?

Test your battery with another Toyota, or V6 and Higher Engines. Thoroughly clean your Terminals.

Hit your starter or another part of the engine to see if it starts.

If you've already done them. Check you spark plugs and cables for rot.

You can also test the electrics to your Fuel pump; if they come clean, check underneath the car for the Fuel Filter. I have come across instances when the fuel filters was malfunctioning after the car was rear ended.

Let us know what else have to done so far.

[tpnotch420]

thanks for the response UCF3

Currently the car is not starting

what I've done so far

tested ignition coils, cam position sensor, crankshaft position sensor, checked for spark at engine, I did discover the driver side cam position sensor wire had made contact with the belt and was grounding out, I've also replaced the battery with a new one

without changing anything when I turn the key I hear no fuel pump

when I either bypass the fuel pump ecu or jumper FP & +B on the diagnostic port under the hood nothing happens until I turn the key. after turning the key on I hear the fuel pump. The dampener screw rises to indicate pressure I can hear a hissing sound under the food by the FPR and I can feel fuel pressure in both fuel rails but I have not tested the pressure yet as I don't have a gage. when i turn the key off the fuel pump continues to run until I disconnect the battery

[UCF3]

It sounds like the fuel injector, the Pressure that you haven't been able to test yet, or maybe something as simple as the Starter motor. did you hear the crank?

[tpnotch420]

yes when I try to start the car it cranks like it's trying to start that's all I get. I was gonna see if advanced auto has a fuel pressure tester so I can try to narrow down my search for the problem. You could very well be right I read some post that lead me to believe it might be the fuel pressure regulator. I just hope it's not the ECU

[wikdsc]

"okay I have a 92 SC400 that won't start so after doing some research I thought I would troubleshoot the fuel system. When I turn the key on I can't hear the fuel pump running so I decided to try the FP ECU bypass to see if it's the pump or the ecu that is causing the problems. Now when I turn the key on I hear the fuel pump running, but when I turn it off the pump will continue to run until I either disconnect the battery or remove the EFI relay. I'm pretty sure the system isn't suppose to work like this.

Does anyone have any idea what could be causing this? Is it likely to be the engine ECU "

first have you tried swapping relays with one that looks the same to see if the relay didnt short its self internally?

[tpnotch420]

wikdsc thanks for the response

Yes I did swap the relay under the hood there are actually 2 more relays that are the same as the EFI relay and I tried both of them and got the same response. I know it's possible but I just don't think all three relays could be bad. I will look for the specs on it and test it with my meter to ensure it's functioning properly

[UCF3]

I don't think it's the ECU yet. any luck with the compression test? btw I never asked you whether the timing belt was okay, is it? Also, disconnect your factory alarm and try to start it. This could be the problem.