No spark with direct wire fuel pump

[speedfreak]

Car tries to start after pulling efi fuse but dies after a couple of seconds then won't spark , I have my walboro pump wired directly to a key switched relay . I think that the ecu is telling it to cut spark after sensing fp is not wired properly but won't throw a code. Any ideas?

 

[jetjock]

The engine can't possibly run after pulling the EFI fuse and what you're thinking about the ECU is wrong.

 

[speedfreak]

Sorry just pulling efi fuse to clear codes and reset ecu then putting it back in to start. Ecu can't cut fuel huh? the fp is unplugged as far as it knows. Not sure why it's not getting spark I'm watching it via timing light. After pulling the efi fuse and replacing it. it fires up then dies, I can see the timing light flash when it starts but then it stops and car dies. After that i Get no spark

 

[hvyman]

Did you have codes originally?

 

[speedfreak]

No, just changed The car back to stock from a standalone. Thought it might throw a code 78 ( fuel pump control signal

 

[jetjock]

So this isn't a 7M ECU? What engine is in the car?

 

[speedfreak]

It is a 7mgte with stock ecu. I just googled up some obd1 codes for Toyota thought thy were universal. Anyways my question is will the stock 7mgte with original ecu run the car with the fuel pump being directly wired or does its power need to come from the harness?

 

[jetjock]

The stock ECU controls the fuel pump but doesn't care if it gets power from elsewhere. There's no feedback ie; it doesn't 'know' if the pump is running or not. And that code you mentioned isn't valid for a stock ECU. I suggest troubleshooting by using the TSRM and TEWD. Based on your symptoms I'd be looking for a code 14.

 

[speedfreak]

Thanks jj! Then the search for spark is on!

 

[jetjock]

Welcome. With the stock setup the pump won't continue to run unless the engine starts but that doesn't apply to you. Far be it from me to deny anyone the opportunity of becoming a crispy critter after a collision but if it were me I'd add that safety back using an RPM or inertia switch. Either are cheap and readily available.

As for spark all the system needs to generate it is a working CPS, ECU with power applied, coil packs with power applied, a functional and grounded igniter, and good wiring between them. With those things you could, with the key on, spin the CPS by hand and make spark all day long.

 

[speedfreak]

Exactly what I wanted to know! Thanks again, as for emergency fuel cut I will be going back to my standalone after smog which also cuts fuel when no crank detected after three seconds thanks for the concern though.

 

[Nick M]

Ecu can't cut fuel huh?

Yes, by halting injection when there is no spark signal.

 

[speedfreak]

found it! turned out to be unconnected ground from wire harness, must have been occasionally grounding and giving me spark. thanks all

 

[jetjock]

Hmmm. Curious as to which wire it was since off the top of my head no grounds other than the igniter chassis are required.