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Electrical Gremlins

Old 01-01-19, 04:31 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, 04:47 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, 05:43 PM
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misread your last post Nemo

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Old 01-05-19, 12:56 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, 01:37 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, 12:16 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, 01:44 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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Old 01-27-19, 02:18 PM
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I'm back! Today I managed to get some decent weather (40s) and tested the plugs. I bought brand new plugs, disconnected one of the leading plug wires, hooked it up to the new spark plug, grounded the plug, and there was no spark. Now I suspect something else along the way isn't right. Maybe I disconnected something when removing the front harness and didn't plug it back in (like I did with the fuel pump resistor). I'm going to do some reading and try to figure this out.

Also, it seems to me like I can easily get to the plugs from the top without removing anything. Maybe it's because I don't have the stock setup, but there's a clear shot right down to where the plugs are and I can easily fit a socket wrench. That's a slight relief.

Any thoughts on the lack of spark, feel free to suggest. The only thing I'm thinking of right now is the crank angle sensor, but I don't think I disconnected that or interacted with it at all when I removed the front harness.
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Old 01-28-19, 07:54 AM
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If your tach bounces when the engine cranks over, the CAS is probably OK. Check the wiring to the coils and make sure they are getting power.

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Old 01-28-19, 11:59 AM
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Wow, simply wow. Troubleshooting multiple failures isn't for the faint at heart

Have you checked your clutch interlock switch
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Old 01-29-19, 03:11 PM
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TomU,

Thanks for the added thought about the Clutch Switch. However, I don't believe Nemo's current problem is about the starter relay & logic circuit. I could be wrong but it sounds like the car cranks but lacks spark.

Nemo,

You may want to double check the spark plug wires for any breaks along its length and that they seat fully onto each plug. You should feel it snap into place and may hear it snap into place too. Have you tested the Coil Packs & Igniter? Refer to Section G, Pg G-20 in the FSM for testing of the Ignition Coil & wires and Pg G-22 for testing the Igniter (assuming stock components).

Keep on trucking! You are weeding out all of those electrical gremlins and its reward will be worth the wait.
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Old 01-30-19, 04:18 PM
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I actually don't have the gauge cluster hooked up, so I'll hook it up and see if the tach does bounce.

Clutch interlock switch is definitely good.

It'd be weird to me if there's some problem with the plug wires. They're brand new and were installed when the engine was rebuilt. Visually they all look like new and they were connected correctly. The engine was rebuilt and I brought it home running fine. The things I did since it got back home were limited to fixing body electrical issues, so I didn't touch anything on the engine. Hopefully I'll figure it out. The weather is going to keep me away from it for a while.
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Old 03-03-19, 01:15 PM
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I think I know what the problem is. Inspecting the wiring diagram, I noticed this about the Igniter.



There are clearly 7 wires on its connector, which I labeled above 1-7. I also labeled a connection to the common ground as ?, because where is this supposed to be?

I think I know where.




Pretty sure the Igniter connects to the common ground by being bolted directly to the chassis. And, these bolts sheered straight off at the head when I tried to remove them.




My guess is, if I bolt the Igniter back to the chassis, all will be as before. Let me know if you all agree.
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Old 03-03-19, 02:33 PM
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Yes, the bolts ground the igniter to the chassis. I bet dimes to donuts that will fix your spark problem. You are kicking the @$$es of those electrical gremlins! Do you have a tap & die set to remove those screws and rethread the holes?
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