Possible bad ECU?

[KillHirro]

A little bit ago I had a fuel leak on my car, specifically it was that fuel leaked through the firewall port right next to the secondary fuel filter. This fuel made its way into the cabin and drenched basically everything in fuel in that quadrant of the inside. Right when I was pulling back into home, the tachometer shut off, signals stopped working, and the coolant gauge went kaput, but the engine kept running and the speedometer still worked. Along with that, the battery light still functions properly. I have since fixed the fuel leak and cleaned/dried everything I could see.

Another thing to note, the car doesn’t register turning the key into the third position, just before cranking the car. It seems to only work in the first and second positions properly.

The car ran great aside from the tach and coolant gauges not functioning, until today. I started it just fine and it idled for about 2 minutes, then died on me. I have a pressure gauge on my fuel line that reads no pressure when the car is on. I have tried turning the key back and forth and still no fuel pressure. I have tried resoldering the joints on the grey fuel pump relay on the backside of the interior fuse box. As far as I am aware, I don’t have that small black fuel pump relay mounted on the left hand side to the right under the steering wheel. For reference, I have an ‘89 LX sedan with a weber swap.

I thought my ECU was bad or i shorted something out, but upon a visual inspection there are no blown diodes, capacitors, or resistors.. everything (visually) appears intact.


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[ShiRen]

Man I was for sure until you said you had a Weber lmao. You don't have an ECU... Well there's kind of one, but once there's no more vacuum stuff the only thing it can control is the fuel shutoff in the stock carb, so with a Weber it doesn't even do that.

You want to take a look at your fuse box under the dash or something, it sounds like you just don't have power. Does ANYTHING work aside from like the headlights maybe?

[Ursula87Kludge]

Here's a kludge that I did years ago: get a roll of 18ga wire, a ring terminal, an inline fuse, about 10 amp, a rocker switch, and a couple of spade clips.
The fuel pump is under the carpet behind the back seat. It just runs off of 12 v from the battery. Connect your new wire harness like this: battery terminal, ring terminal, fuse holder, six feet of wire, the rocker switch, about ten more feet of wire, spade clip. Use a VOM to see which side goes to chassis ground. Make another little harness for right there in the trunk to put the fuel pumps negative side to the chassis. (You may have to drill a sheet metal screw off to the side to make a ground.)
Stick the wire through the A/C drain hole in the firewall, add the fuse and ring terminal in the engine compartment and hook it up to the battery positive post clip bolt(the tightener). Add the rocker switch somewhere beside the driver's seat, unroll the rest of the wire around the back seat, crimp on the spade clip, an you're ready to hook it up.
Of course put the ground side on the negative, and your new harness on the positive (a red and a black permanent marker help here) and it should deliver up to 10A of car battery voltage whenever you flip the rocker switch. On a quiet day you can listen for the whirring of the fuel pump.
I did this kludge to get around a bad main relay, and ran the fuel pump off of the cigarette lighter for most of a year. It can not only test out the fuel pump, it can do all sorts of tricks when you want to deliver fuel pressure and an unusual time in the start cycle. Just don't leave it running all night long!

[KillHirro]

Thank you for the responses.
As per my due diligence I should update with what the problem ended up being. When gas got into the car from the firewall passthrough, it pooled up and got onto the wire bunch that goes to and from the ECU. When this happened, it shorted a fuse, which I thought was good.

It was the fuse that controlled the side indicators that blew, so after replacing that the entire gauge cluster works again.

As for the car dying on me randomly, it was because I shorted out the gauge cluster fuse (and didn’t realize that included the fuel gauge) and I ran out of gas. Quick jerry can pick-me-up and it was back on the road.

Are there any issues that could come about from running the engine dry? I tried to crank it for a little while too, about 1.5 maybe 2 minutes total of cranking.

As for the fuel pump switch, I’ll give it a go, thanks for the idea. I’ve been wanting to install a killswitch for a bit now.

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[Dr_Snooz]

LOL, always start with the simplest fix. Running the car out of gas can shorten the life of the fuel pump, and possibly clog your fuel filter. Nothing really major though.