No ECU, FP, or coil power

Asked by Jul 31, 2017 at 07:47 PM about the 1991 Subaru Justy 2 Dr GL Hatchback

Question type: Maintenance & Repair

Tl;dr: no power to ECU, Fuel pump, or coil, but power to
everything else. Not sure what to check next, maybe
igniton lock...?

Ive got a mystery in my Justy. Bought it a few weeks ago,
running and driving, it ran about as well as a 90's
carbureted car with 187k miles could be expected to run. I
repaired some exhaust leaks(made it run worse), then
changed the oil(made it run worse), then did a full tune up
with plugs/wires/cap/rotor/air filter/fuel filter(made it run
awful), took it to a shop for a full inspection and they only
found expected things like brakes and suspension
stuff(car will now no longer idle without holding
accelerator), then parked it after a rather long drive, and it
never started again.

So, i checked fuel(good), air(good), spark(good),
timing(okay), and compression(bad). 110psi on cylinders
2-3, 70psi on 1. Wet test made no difference, so removed
the head, had it rebuilt, and replaced the head gasket(and
numerous other gaskets and seals, including timing belt
and tensioner while I had it apart). Upon reinstall, it still
wont start...

However, when I rechecked my basics, I had fuel(none),
air(good), spark(none), timing(good), compression(good).

Found that the fuel pump was not working. Tested the
plug, no power to fuel pump.

Tested the fuses, all good(even under hood).

Tested the relays, all good.

Then I noticed that my check engine light was not coming
on when I turned the key to RUN.

I removed the ECU and took the case off, and it looks
brand new. No leaky capacitors, no water or physical
damage, not even any dust. Checked the harness pins,
none broken or bent. Reinstalled and still nothing.

I do have power to everything else, and my oil pressure
and charge lights light up when I turn it to RUN, but but
not to anything that might make the car useful as an
automobile...

So, here I am stuck. Ive no idea what to check next, and Id
like to have it running soon so my neighbors will leave me
alone.

Thanks!

5 Answers

Well, ive checked the ignition switch, and its fine... Im sort of thinking its the ECU now, after removing it again and having the exact same symptoms. If you have a problem and remove a component, and nothing changes, either thats the problem, or the component is unrelated to the problem system... Lol

82,835

That is a lot of work to put into an old Subaru. Is it worth it?

I bought it with the knowledge it was a project and would take a lot of work. As a mechanic, Im always looking to up my skills, so you would have to define "worth", being as its a relative and contextual term. Im doing all the work myself, which is costing me nothing because I enjoy it. Im getting the parts at cost, and honestly returning most of them as I test against my old parts, so im actually not financially in it too deep. So aside from the effort, which is a retarded thing to not want to expend, i would say so far yes, its worth it. If I cant get this electrical issue sorted and the car never runs however, then the gained experience will not outweigh the costs, and ill be inclined to sell it. That being said, this has gotten me no closer to solving my problem. Any ideas on what I could check next?

82,835

Have you used a multi-meter to verify that the ignition switch is working properly? If you are not getting power to the ECU, trace it out until you find the fault.

It took a few days, but I finally traced the entire starting charging system, including the ecu... And it all checked out. Good news and bad news, though. Good news, I fixed my problem. Bad news, no idea how I did it lol. After tracing everything, it still didnt work, so I retested all the relays with a separate 12v power source(cordless drill battery) and a multimeter, and they were all fine. Then when I reinstalled them, the fuel pump suddenly came on and I had full power again. I can only assume I had a loose or shorted wire somewhere that got bumped the right way, or one of the relays was stuck and my click-and-continuity test unstuck it... Anyway, it runs again, and it runs great now. After a full tank(7.35 gallons. Supposed to be a 10gal tank though...) it went almost 260 miles. Not bad for a carbureted '91 lol

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