75 390 wont run help!
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75 390 wont run help!
ok i have a 75 f100 ranger with the 390 big block in it, it was runnin good and then all the sudden it started missin and bam shut off. so i thought hmm ran out of gas so i put gas in it and tried to restart it, it wouldnt start so i dumped gas in the carberator and nothin, then tried startin fluid nothin, the points, condensor, rotor, and cap and plug wires and plugs are brand new. its gettin fuel and theres fire to the plugs. it wont try to start unless i advance the timing alot but then it just kinda hickups for a second then goes back to tryin to start any ideas wat it could be?
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Once an engine becomes a high-miler , a timing chain and gears can become suceptacle to "Going any time".
meaning: just running the chain can shear off the last part of a gear & become even more "Out of Time"
Do you know how to do a timing chain to gear slop test ?
This is to verify the timing set is either toast or still okay.
You have air
You have fuel
Do you have spark ?
Do you have spark at the correct time and spot ?
Let's find out
BTW <> I forgot to Welcome you to the site
meaning: just running the chain can shear off the last part of a gear & become even more "Out of Time"
Do you know how to do a timing chain to gear slop test ?
This is to verify the timing set is either toast or still okay.
You have air
You have fuel
Do you have spark ?
Do you have spark at the correct time and spot ?
Let's find out
BTW <> I forgot to Welcome you to the site
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Okay grab a socket that fits the crankshaft bolt
also get a breaker bar and socket.
Take the distributor cap off
Now put the breaker bar socket on the crankshaft bolt and turn it one direction or the other until you see the rotor in the dist turn a little......... stop
Now you need to reference the bar as in a circle.
Start turning the crankshaft the OTHER direction making note of how many degrees of a circle it takes before the rotor starts to move. 10*, 20*, 30*,45* etc
The circle being 360*
get back here with the results
also get a breaker bar and socket.
Take the distributor cap off
Now put the breaker bar socket on the crankshaft bolt and turn it one direction or the other until you see the rotor in the dist turn a little......... stop
Now you need to reference the bar as in a circle.
Start turning the crankshaft the OTHER direction making note of how many degrees of a circle it takes before the rotor starts to move. 10*, 20*, 30*,45* etc
The circle being 360*
get back here with the results
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Postmaster
Joined: Jul 2005
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Are the plug wet from gas?
reCheck the firing order.
Definitely give the engine a timing chain slop test as Mil1ion mentioned.
reCheck the firing order.
Definitely give the engine a timing chain slop test as Mil1ion mentioned.
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Postmaster
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I have worked on trucks, where the distributor gear cotter pin had sheared. Place the harmonic balancer on Top Dead Center (TDC). Then remove the distributor cap noting the location of the number one spark plug wire in reference on the distributor housing. The rotor should be approxiamately pointing to the number one spark plug wire on the distributor cap.
Remove the distributor and verify the cotter pin on the gear, make sure the cotter pin has not sheared. Verify the gear on distributor shaft does not turn freely on shaft.
Follow these step in reverse to order for reinstallation, set timing using a timing light and to engine specifications.
Remove the distributor and verify the cotter pin on the gear, make sure the cotter pin has not sheared. Verify the gear on distributor shaft does not turn freely on shaft.
Follow these step in reverse to order for reinstallation, set timing using a timing light and to engine specifications.
Last edited by 1975Ford; Jul 25, 2006 at 06:20 PM.
Senior User
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Sounds like the timing chain jumped all right . Turn the engine over with the tappet cover off, until the #1 exhaust is just closing, and the intake is just opening. This is TDC, split overlap. Now check the timing marks. If they aren't lined up, the chain has jumped.
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Similar trouble
Hello, Mark here. I have a similar problem with my truck; It is a '74 f-250, 22K miles on a professionally rebuilt 390. It had been running well except a occasional miss when stopped in drive, started up fine until 2 days ago. It cranked long, then would start, then would not start at all. I checked coil spark...OK... then put the coil wire back on and it started fine again for 2 days. I did a much needed tune-up...points, condensor, rotor cap, wires, even coil. The firing order is correct, the point gap is .017, the plugs are Bosh Platinum pre-gapped @ .044.
I did the timing slop test...the rotor moves almost immediately.
I have spark at the coil and plugs.
I have gas going to the very new 4BBL Edelbrock Performer carb.
The truck ran fine and stared fine until I did the tune-up. Now it just cranks.
What the heck did I do?? What am I missing here?
Any help would be appreciated!
Mark
I did the timing slop test...the rotor moves almost immediately.
I have spark at the coil and plugs.
I have gas going to the very new 4BBL Edelbrock Performer carb.
The truck ran fine and stared fine until I did the tune-up. Now it just cranks.
What the heck did I do?? What am I missing here?
Any help would be appreciated!
Mark
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Mark Welcome to the site.
It is always best to make your won thread reragrding your topic even if it is the same.
*Look for : Post New Topic*
The gist of any Thread should be centered on the original post of the thread otherwise we will be all over the pace answered the wrong person..it gets confusing.
Maybe a Moderator ( ERIC !) will move your post to have its own thread so we can keep everything in order.
I'll answer once it has been moved
It is always best to make your won thread reragrding your topic even if it is the same.
*Look for : Post New Topic*
The gist of any Thread should be centered on the original post of the thread otherwise we will be all over the pace answered the wrong person..it gets confusing.
Maybe a Moderator ( ERIC !) will move your post to have its own thread so we can keep everything in order.
I'll answer once it has been moved
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Uncle Buck.
I thought it was always best to line the rotor up with something on the engine (Like a bolt) as opposed to something on the distributor which is being removed anyway ?
The position of the vacuum advance has to be referenced as well.
I thought it was always best to line the rotor up with something on the engine (Like a bolt) as opposed to something on the distributor which is being removed anyway ?
The position of the vacuum advance has to be referenced as well.