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Electrical Gremlins

Old 01-01-19, 05:31 PM
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I thought that, but should I still hear the fuel pump pressurize even if it's flooded? A lil more context, the car has a PowerFC, not the stock ECU. Is it possible from removing the battery that something isn't configured correctly now?
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Old 01-01-19, 05:47 PM
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Nemo,

Do you have a base tune on the PFC or was it custom to your application? How stable was it when returning from your engine builder? I am unfamiliar with PFCs so maybe someone else may chime in with better advice. From a stock application, the motor does have a tendency to flood when started and then shut off before engine warm-up was completed. For example, moving the car from the garage to the driveway and then shut down may cause flooding, especially on old & tired motors. It sounds like your motor is highly modified and may be more fickle during start-up.

I hope this helps a little. I would recommend checking for spark first. If that is good then test the fuel pump - do fuel pressurization checks from the FSM, Section F, around Pg F-106 (or close to it). The 93 FSM procedures may only cover tests using a diagnostic box. Try the procedures for fuel pressurization from the 94 FSM. That is more in-line with a DIY-er.
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Old 01-01-19, 06:43 PM
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misread your last post Nemo

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Old 01-05-19, 01:56 PM
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Originally Posted by Gen2n3 View Post
FSM, Section F, around Pg F-106 (or close to it).
That was the lightbulb moment right there.

Originally Posted by Blk 93 View Post
misread your last post Nemo
Saw your original reply and wanted to give thanks.

So guys, this is what it came down to. I thought, the problem should be a lot simpler than something like inspecting all the wires again. I trusted my wire work, so what else could be wrong...

I inspected the FSM like George said and checked the fuel pump power line Blk thought. Turns out, I had continuity in sections, but no voltage at the pump.

I checked the wiring diagram and then understood where the various connections were expected to be continuous. So I measured between devices until I realized, where the heck is the Fuel Pump Resistor???

First, it wasn't connected, at all. The connection was just hanging there in the engine bay. But I looked around and couldn't find it! First I thought it was the condenser, but the wire number (1 vs 2) and the color didn't match. I grabbed a flashlight and probed all around that side of the engine bay until I saw what looked like another ignitor way down near the firewall... with a connection on it that was not hooked up to anything.

Crazy thing is, I have no idea how I disconnected that thing when I removed the front harness. My hands are big, and it was difficult reconnecting it just now. I did that, hooked up the negative to the battery, turned the key to on... and the fuel pump turned on finally. =)

Today is a crap day for weather so I'm gonna wait till tomorrow to try to crank it. I want to make sure I can leave it running for a while and then drive it for a bit. But this seems like it. Seems like I'm finally at the finish line. Pretty silly oversight on my part.

Thanks for the help. Tomorrow we'll see if this thing will finally drive properly, with functioning lights and everything!
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Old 01-05-19, 02:37 PM
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Nemo,

Not to sound like a broken record, but I'm glad to lend a hand! It's good to hear that you found the culprit to your fuel pump not powering up. Let us know how your tests go for tomorrow!
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Old 01-06-19, 01:16 PM
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Today I tried to crank it, same as before but at least I hear the fuel pump on. I also see the fuel pressure on the FPR under the hood (an Aeromotive). And I do smell gas now. I know it's also tuned rich right now for the break-in period after the rebuild.

I tried WD40 in the UIM nipple, but no change. Maybe it's possible the spark plugs are fouled, but I find that weird since the car was just sitting there. I drove it home after the engine rebuild, would start it up once in a while to let it warm up and idle for 20 mins or so, give it some liberal 4k RPM revving in my driveway, then park it back in the garage. Once I started taking the interior and front harness apart, it just sat not being started. So the spark plugs were basically new at that point this summer.

But, at least I know what to check next. Many electrical problems down, one more problem to go!
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Old 01-07-19, 02:44 PM
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You're getting there!

It is possible if you are smelling gas that it's really flooded at this point. Get a new set of JUST leading plugs and swap those out, also crank the motor with the ECU fuse pulled and plugs out to pump some of the gas out.

I've seen plugs that looked shiny and new that were fouled and had the weakest spark ever. You can't beat new plugs for starting a problem motor. You don't need all 4, the leading plugs are what do most of the work. If the trailings are fouled they will clean up once the engine is running.

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