390 no-start problem
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Posting Guru
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390 no-start problem
Trying to help my buddy with his 390.
He drives it once every few months- always runs great.
The last couple of times, he had to really fight to get it started (lacquer thinner, starting fluid, etc). After it started, it ran fine.
The next time he tried- absolutely nothing. The engine will not even sputter.
We've verified a nice fat blue spark (courtesy of a MSD box). The rotor is spinning, so the timing chain isn't broken.
He wants to tear it down, but I think we're missing something simple.
With it not even coughing/sputtering, it seems like an electrical issue, but we've checked that. Could a jumped timing chain do this?
He drives it once every few months- always runs great.
The last couple of times, he had to really fight to get it started (lacquer thinner, starting fluid, etc). After it started, it ran fine.
The next time he tried- absolutely nothing. The engine will not even sputter.
We've verified a nice fat blue spark (courtesy of a MSD box). The rotor is spinning, so the timing chain isn't broken.
He wants to tear it down, but I think we're missing something simple.
With it not even coughing/sputtering, it seems like an electrical issue, but we've checked that. Could a jumped timing chain do this?
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Checked the ignition switch? How about the ballast resistor wire - you'll have a nice spark in 'start' (12VDC) but if it's burned out/gone, in 'run' you won't get the 6 -8 VDC to keep it running.
Brain box (ECM) and connections? ( don't know much about the MSD stuff.....same thing?)
Too much play in the timing chain? - check rotor movement with crank movement. Ignition module? The timing OK?
Brain box (ECM) and connections? ( don't know much about the MSD stuff.....same thing?)
Too much play in the timing chain? - check rotor movement with crank movement. Ignition module? The timing OK?
Post Fiend
Joined: Sep 2006
Posts: 14,325
Likes: 14
From: Island Southeast Alaska
May be a loss of compression. Try a Little oil
in the cylinders to bring the compression up a bit.
Not to much or it may foul the plugs. I am thinking
the rigs are stuck from sitting and not ran much.
Do a compression check wet and dry. Cant hurt
and can tell you a lot about your engine.
in the cylinders to bring the compression up a bit.
Not to much or it may foul the plugs. I am thinking
the rigs are stuck from sitting and not ran much.
Do a compression check wet and dry. Cant hurt
and can tell you a lot about your engine.
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Posting Guru
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This is what my buddy is thinking. But even if the rings did stick, wouldn't there be enough compression for the motor to cough/sputter/backfire...anything at all?
i mean- this thing is DEAD. no signs of life whatsoever.
i mean- this thing is DEAD. no signs of life whatsoever.
Post Fiend
Joined: Sep 2006
Posts: 14,325
Likes: 14
From: Island Southeast Alaska
The cylinders may be washed down from the use of starting fluid.
And it may well not even fire on start fluid if this is the case.
Just try a little oil down the plug holes and it may start right up
Better yet do a compression check and know for sure.
And it may well not even fire on start fluid if this is the case.
Just try a little oil down the plug holes and it may start right up
Better yet do a compression check and know for sure.
Logistics Pro
Joined: Mar 2005
Posts: 3,771
Likes: 80
From: tujunga, calif
Very possible a worn timing chain/gears could jump. Turn the engine over by hand until the timing mark lines up on the compression stroke of #1 cylinder, then check the position of the rotor to see if it is pointing to the #1 on the cap.
Elder User
Joined: Nov 2009
Posts: 891
Likes: 0
From: Mayfield, KY
Many years ago I had a guy at work who drove a 80's full size Bronco and that happened to him. Ended up having to do a ring job. I was blown away at that as I had never heard of it happening before....
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Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
I would think you'd get a fart out of at least one cylinder.....What do the plugs look like?
Try the 'ol finger compression test as suggested...you said you have spark.....fuel? Compression test/leak down. Have many mice ( meeses?) gnawing away at the electrical lines? Corrosion on the +/- battery and starter?
Try the 'ol finger compression test as suggested...you said you have spark.....fuel? Compression test/leak down. Have many mice ( meeses?) gnawing away at the electrical lines? Corrosion on the +/- battery and starter?
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Cargo Master
Joined: Dec 2015
Posts: 2,544
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From: Harned, Ky
With nothing was said about the mileage on the engine, so with it having spark and gas I'd do what hiball3985 said ^^^
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