Engine: no start
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Lead Driver
Joined: Apr 2001
Posts: 6,335
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From: Midwest
Engine: no start
ok, this is my 1978 f100 with a swapped in 86 351w HO. I haven't started the truck in about 3 months,thought I would try it today. The engine turns over fine,and it is getting gas and spark. I put a little gas in the carb before I tried to start it to save cranking time. it ran very rough for about 15 seconds and would not start like that again after it died. I even tried to "pickle" the engine by putting a teaspoon of oil into each cylinder to boost compression enough to get it to start. no luck. I can see and hear gas squrting into the carb when I move the throttle linkage. the coil is putting out a nice blue spark and not a weak yellow one. when I pulled the plugs to put the oil in the cylinders,I cleaned them even though they didn't look that bad. I have tried with the choke open or closed,same result. somtimes when it is cranking,it will speed up and almost try to start,but it will not quite run enough by itself to let off the key. I have tried everything I know to do without much luck. looking for things to try that I may have overlooked. thanks for the ideas,Ben
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Lead Driver
Joined: Apr 2001
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From: Midwest
I haven't messed with the distributor. it is the same way it has been since I was driving it 3 months ago. if it were the ignition box, would I be getting spark? the coil shoots a nice blue spark. thanks for the reply bouts21
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Joined: Sep 2003
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From: Hartland, MI
What condition was the engine when you quit driving it? 86 351 would have had nylon timing gears from the factory, they dont like sitting for long periods. Might have chipped some teeth and jumped time. I would start by putting the timing mark on the balancer at 0 degrees then make sure your dist rotor is pointing to the #1 terminal on the cap. If its way off then it has jumped.
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Lead Driver
Joined: Apr 2001
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From: Midwest
zwinstead,the engine ran fine when I parked it. I ran out of time today or i was going to check the timing next. i will do that next time I get a chance to work on it. I did a compression check,and all 8 cylinders were 125-130 pounds. wouldn't the compression be off if the timing was off? thanks for the reply
Last edited by cjben; Jan 30, 2005 at 07:31 PM.
Senior User
Joined: Sep 2003
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From: Hartland, MI
Those compression readings are ok. I ran a check on a 300 6cyl and it had 180 psi in all cylinders. I still think it would run with 125-130 psi. If the timing was off you would see some cylinders with significatly less comp. Now the gear on the distributor shaft could have stripped or the pin that holds it to the dist shaft could have broke, but these are not common problems. If the dist gear is bad for some reason your timing would still be off, but you would have good compression.
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Lead Driver
Joined: Apr 2001
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From: Midwest
the gas tank was almost dry yesterday before I tried to get it running. i put 5 gallons of fresh gas in it,and used fresh gas in the carb when it ran for 15 seconds or so. i was thinking about it at work last night,and it did this last winter also.( I don't drive this truck in the winter). I never did figure out why it wouldn't start last year,just went out one day when the temp was warm,probably 50 or so if I remember correctly and it started right up. so what would make it start when it is warmer out,but not when the temp is in the 30's or below? I hate to admit this,but I have even tried starting fluid and it wouldn't fire with starting fluid. thanks for everybody's help so far,i just want to get this figured out without just guessing and spending a bunch of money on parts that didn't need replaced.
Postmaster
Joined: Apr 2000
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From: SD
Originally Posted by cjben
somtimes when it is cranking,it will speed up and almost try to start,but it will not quite run enough by itself to let off the key.
You said it has good spark at coil, did you check at the plug? A bad rotor, cap or wires will cause the spark to never reach the plugs...
Marty
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Lead Driver
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From: Midwest
marty,I tried every combination of tricks I could think of to get it to start. choke open and closed, foot on the floor with choke open,foot on the floor with choke closed. waited several minutes with the foot on the floor,then tried to start it. I am thinking it must be a weak spark after the coil. I did clean the plugs yesterday when I was trying to get it running. how can I check for spark at the plug? put a plug in the plug wire and ground it to the block or something similar? thanks again for the help