Ignition problem
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Senior User
Joined: Mar 2004
Posts: 280
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From: Alabama
Ignition problem
I'll try to make a long story short. I had recently pulled and disassembled the engine (except removing the crank and pistons), painted everything, reassembled and put it back in. Went to start it and it did start but it would max out at like 2k rpm, let off the gas and it would backfire through the carb and die. If I turn the distributor clockwise it would rev up out of control and would have to turn it off. I triple checked my firing order and assumed I was 180 out even though I knew better. So pulled and restabbed. Truck wouldn't start. So I pulled a plug and the coil wire and had the helper crank it till I knew I was on the compression stroke. While cranking, a spark was flying out the top of the coil and arcing to the neg side of the coil which doesn't seem normal. Moving on, pop the cap and confirmed I was right the first time and went to pull the distributor out and got quite a jolt (it shocked the crap out of me). I have the red/green wire going to the positive side of the coil and green/yellow to the neg plus a wire for the tach. The only other thing I did was wire the choke to the white/black wire from the alternator.
Anybody got a clue to what I screwed up now?
Anybody got a clue to what I screwed up now?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
I don't understand the steps you've taken at all. First the engine ran, but poorly, so you assumed the distributor was 180 degrees out? You even said you knew better, so why would you move forward with that idea? Now the distributor's not in at all?
What's your actual question? Why did the coil arc? Why you got shocked? I can't answer that because I don't really understand what you did.
What's your actual question? Why did the coil arc? Why you got shocked? I can't answer that because I don't really understand what you did.
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Senior User
Joined: Mar 2004
Posts: 280
Likes: 2
From: Alabama
I haven't had time to mess with it since my electrifying encounter but I'm thinking/ hoping it's just a grounding problem. I have the cab and battery grounded to the block and the Core support grounded to the frame but forgot about the block to the frame. And I probably need to sand the block a little where the distributor goes in as well where the distributor contacts the block.
Posting Guru
Joined: Oct 2007
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From: Sedro-Woolley, WA
The only way a vacuum leak can contribute to "runaway" rpms is if you are running EFI and the sensors detect a lean mixture. It will then add fuel to compensate.
The Distributor does does not ground to the block. The circuits run through it but do not terminate there.
You can cause arcing across the coil terminals if you disconnect the coil or spark plug wires. This cause the high voltage side to find an alternate route
Listen to FMC400. He knows these systems inside and out.
The Distributor does does not ground to the block. The circuits run through it but do not terminate there.
You can cause arcing across the coil terminals if you disconnect the coil or spark plug wires. This cause the high voltage side to find an alternate route
Listen to FMC400. He knows these systems inside and out.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Thanks rogue for the kind words. One minor correction, however - the distributor does in fact ground through the block. The distributor is the sole ground of the ignition system, and runs to the ignition module through the BLACK wire. The ignition module returns all primary current to the ground at the distributor through the BLACK wire.
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Posting Guru
Joined: Oct 2007
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From: Sedro-Woolley, WA
Thanks rogue for the kind words. One minor correction, however - the distributor does in fact ground through the block. The distributor is the sole ground of the ignition system, and runs to the ignition module through the BLACK wire. The ignition module returns all primary current to the ground at the distributor through the BLACK wire.
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Senior User
Joined: Mar 2004
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From: Alabama
I had a few minutes to mess it with last night and installed a ground from the block to the frame and cleaned the other ones up for good measure. Unfortunately nothing changed. I started it and sounds like there is a load on the engine and I can hear a slight squeal or maybe it's a whistle, it's hard to tell because the truck is loud inside the garage. It wasn't missing and was smooth for the most part but when you give it some gas it just backfires through the carb and dies. If this sounds like the symptoms of a vacuum leak I have no idea where it would be coming from unless it was under the intake. I did have some issues with getting the coolant passages to seal but after a third attempt with some edlebrock gaskets and using rtv on the front and rear and around the coolant passages it doesn't leak. I'll have some time tomorrow to spray it and check for leaks but in the mean time, any other suggestions or thoughts?
Laughing Gas
Joined: Sep 2003
Posts: 968
Likes: 5
From: Corbett, Oregon
Give some specifics, such as:
What engine?
What intake and carb?
What ignition?
Why did you pull the engine?
What non-stock parts did you install?
I'm not saying your engine has a vacuum leak, though it does sound like it. I am just using a vacuum leak as an example.
While it is easy to say "vacuum leak" sometimes a vacuum leak can be hard to locate. Different Ford engines are prone to vacuum leaks in different locations.
Answering the above questions can help us help you identify and fix your problems.
Roger Carter
What engine?
What intake and carb?
What ignition?
Why did you pull the engine?
What non-stock parts did you install?
I'm not saying your engine has a vacuum leak, though it does sound like it. I am just using a vacuum leak as an example.
While it is easy to say "vacuum leak" sometimes a vacuum leak can be hard to locate. Different Ford engines are prone to vacuum leaks in different locations.
Answering the above questions can help us help you identify and fix your problems.
Roger Carter
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