still won't start
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Joined: May 2007
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Mayday Need Info
I purchased a 77 f 150 with a 351 modified and auto transmission. $400. When I got it home I found out why it was so cheap... The oil pump had frozen up and ripped the teeth off of the lower end of the distributor. Okay, no problem, I replaced the distributor and oil pump. After a great deal of swearing it started but, backfired through both ends and would only run for about two minutes. Found that the timing was set wrong and blew fuel out the carb. Corrected the fuel problem with another carb. Now the truck won't start at all. Turns over great, no problems there. Getting fuel. Checked the electronic brain (first gen), had a bad connector, replaced it. So, I'm getting fuel and a spark. The spark however, is orange meaning weak. It seems to me it should be white or bright blue. I read somewhere that their should be something (forgot what it was called) to tell the distributor to fire a hotter spark. Any info would be a great blessing. thanks.
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Check for timing chain slack or wear first with the diagnostic routine found in your service manual. The timing chain could fail anywhere after 80K miles. Have the ignition module tested at a parts store. The entire ignition system can be tested with the diagnostic routine found in your service manual, a must-have item.
Save the old ones
Joined: Dec 2002
Posts: 666
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From: Boyne Mich
I'ld check the timing chain too. Maybe, As it turns over, use a timging light to see if the timing is even in the neighborhood. Also Check your compression. You can have fuel and fire, but if it doesn't get squeezed then it won't run. Should be at least 125 psi, could be as high as 165 psi. If it had been setting a long time I put a little shot of oil in each cylinder to wet the rings a little. That will raise the compression 10-15 psi. But that all assumes we are dealing with a not so great engine.
The distrubutor gets it's signal from the Ignition module which gets its signal from the Pick up coil in the bottom of the distributor. That is what I Think your trying to think Of.
Good Luck
Shawn
The distrubutor gets it's signal from the Ignition module which gets its signal from the Pick up coil in the bottom of the distributor. That is what I Think your trying to think Of.
Good Luck
Shawn
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Welcome to the site.
First off that 351 is just called the 351M.
The term modified is a misplaced term.
They put a fibre gear on the camshaft on these engines for sound reasons and as a result they breakdown faster and thoow the engine out of time from breakage and strippage of the chain.
Common thing on hi-milers
I suggest to do a timing chain to gear slop test to see what you facing you before you go any further.
First off that 351 is just called the 351M.
The term modified is a misplaced term.
They put a fibre gear on the camshaft on these engines for sound reasons and as a result they breakdown faster and thoow the engine out of time from breakage and strippage of the chain.
Common thing on hi-milers
I suggest to do a timing chain to gear slop test to see what you facing you before you go any further.
Laughing Gas
Joined: Feb 2007
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From: hohenwald, tn
if you think your truck is bad, you should see the f350 i bought from a dealer off ebay. the dealer said it needed a tuneup and the tank drained. it now has 0 none tires on it all the brakes have been replaced lots of things missing no radio cut and taped wiring all over and alot of ROT.
Laughing Gas
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From: hohenwald, tn
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Post Fiend
Joined: Jan 2003
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From: Montana Territory
Originally Posted by Mil1ion
They put a fibre gear on the camshaft on these engines for sound reasons and as a result they breakdown faster and thoow the engine out of time from breakage and strippage of the chain.
Common thing on hi-milers
I suggest to do a timing chain to gear slop test to see what you facing you before you go any further.
Common thing on hi-milers
I suggest to do a timing chain to gear slop test to see what you facing you before you go any further.
I've ripped into a dozen or so of these motors, and NEVER seen a fibre gear on any ford motor.
A weak orange spark would signify a bad or weak ground. check the bolts on the ignition module, the battery ground cable, and for any bare wires. If all of those are good, it could mean the coil is getting old and weak, try the wires first though, its most likely something simple.
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Posting Legend
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I have never seen one without a "composite" gear unless it had been replaced. They all had a nylon covered gear or what was left of it. Never a fiber gear tho.
Parts store OEM silent chain replacement units are steel with the retarded cam timing keyway in the crank sprocket. The aftermarket roller chain units often have multiple keyways on the crank sprocket. Some have +4 +2 0 -2 -4, and some have +4 0 -4 and others just have 0.
The ignition module is not grounded thru the case. It is grounded thru the black wire to the distributor housing. Part of the pickup assy. There were a few aftermarket modules that were grounded thru the case also. This usually resulted in the black wire to the distributor smoking...
Parts store OEM silent chain replacement units are steel with the retarded cam timing keyway in the crank sprocket. The aftermarket roller chain units often have multiple keyways on the crank sprocket. Some have +4 +2 0 -2 -4, and some have +4 0 -4 and others just have 0.
The ignition module is not grounded thru the case. It is grounded thru the black wire to the distributor housing. Part of the pickup assy. There were a few aftermarket modules that were grounded thru the case also. This usually resulted in the black wire to the distributor smoking...
Posting Legend
Joined: Sep 2001
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I replace any OEM timing set with over 80K on it just as a precaution. Don't wait for them to go bad. Most of these old trucks are way over 100K.
BTW, the automakers use silent chain for less noise, high strength, and long wear in many applications:
http://chain-guide.com/applications/...oth-chain.html
BTW, the automakers use silent chain for less noise, high strength, and long wear in many applications:
http://chain-guide.com/applications/...oth-chain.html
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Okay fellas. let me add some more: It also has a new timing gear and chain and I made sure the gears lined up and on the intake (TDC). Today I put in a brand spankin" new ignition module and starter solonoid. Also found a wire to the solonoid UNDER the solonoid and not hooked up, is now... and put 2 new connector ends on the both +/- posts on distributor. Sounds like it will start but just won't. Also still backfires through the carb. Also reads 20 v through battery and solonoid. Next week it just may get a 360 installed. Have to have something to get to work in. No plates, regs. or insurance ect on other truck. Just waiting for the ticket and/or tow. I live in the boondocks.
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still won't start
Maybe duplicate post sorry... Anyhow, 77 f150 w/351m still won't start. Replaced so far... oil pump, distributor, starter solonoid, ignition module, timing chain and steel cam gear, also checked plug wires and firing order. Backfires through carb, can't get a timing mark with light, (aligned timing marks and at tdc compression stroke). Also repaired wire connector (4 pin) to ignition module and +/- on coil. It's gotta be something simple that I'm missing. If I can't get it going by next weekend I'm going to drop a 360 in its place. Don't have a choice. I live in the boonies and the other truck (borrowed from my brother) has no plates, registration or insurance. Just a matter of time before:
1. I have a heart attack from the driving challange
2. Get a ticket
3. Get towed or
4. all of the above
1. I have a heart attack from the driving challange
2. Get a ticket
3. Get towed or
4. all of the above
Last edited by Ron Lee; May 6, 2007 at 09:21 PM.