351 will not fire
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 432
Likes: 0
From: Pulaski, TN
351 will not fire
i have a 78 f-100 with 351w holly 4 barrel carb, carb has problems but cant get it to fire and start at all now i changed the plugs,wires,distributor cap, rotor button . ignition coil and module and still no fire.
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 432
Likes: 0
From: Pulaski, TN
its a new carb just needs tuning gas is getting to the carb but i have no fire on the plug wires, i have fire on pos+ ignition coil. it started this morning then it finally died when i tried to let it idle( it was too cold to idle)
Posting Guru
Joined: Mar 2007
Posts: 1,119
Likes: 0
If it doesnt idle when cold then Id suspect a choke problem. If you have an auto choke, you can manually set it by taking the air cleaner housing off and pressing the throttle back and holding down the choke arm, then release the gas and it should stay. Then try firing it up.
Senior User
Joined: Aug 2007
Posts: 167
Likes: 0
From: Ogden Utah
Just remember the three things that make an engine run is compression, fuel, and spark. start by doing a compression check, If compression is good then check fuel flow to the carb. If that checks out fine then check for spark. The easiest way to check for spark is to connect a timing light to the number one plug wire and hold the trigger while someone else cranks the engine over. The fuel check is easy too just pull the fuel line off the carb and crank the engine. If no gas comes out then check the fuel filter and if that is good troubleshoot the fuel pump. Sorry I just went back and read everything on the post. Try another ignition box, It could have taken a crap.
Last edited by Cobra Highboy; Jan 20, 2008 at 09:31 PM. Reason: adding more
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 432
Likes: 0
From: Pulaski, TN
I Have Now Replaced The Distributor, Cap, Button, Ign. Coil, Ign. Module, Plugs, And Wires, And Still When I Check The Spark There Is No Fire. I Have Fire On The Pos. Of The Coil But Not On The Neg. THE MANUAL SAYS THAT IF THERE IS POWER TO THE + BUT NO POWER TO THE - WHEN GROUNDED THEN THE COIL IS PROBALLY DEFECTIVE BIUT THIS IS THE 3RD COIL I HAVE TRIED.
Last edited by jimbob21rc; Jan 22, 2008 at 09:52 AM.
Posting Guru
Joined: Mar 2007
Posts: 1,119
Likes: 0
I used to do this on old points trucks, i dont see why it wouldnt work here. Hook the test light clip part to the new side of coil and touch prong to pos side of coil. Then, crank it and see if it blinks on and off. If it does, then your module and coil are properly working.
Trending Topics
Thread Starter
|
Senior User
Joined: Feb 2005
Posts: 432
Likes: 0
From: Pulaski, TN
i have now replaced the ignition switch. and now i have also found out that the fuse that says ign coil does not have any power on it at all on neither side, it has two blue/red wires at the powersource part of the fuse and 1 blue at the othe side. i have tried to trace this wire the book says blue/red to ignition switch but i didn't find a red/blue there. i appreciate all the help yall have given me. thanks guys any more advice is more than welcome
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Senior User
Joined: Sep 2006
Posts: 137
Likes: 0
Put your test light on the - side of the coil and crank it. It should blink if your primary ig system is working. If it doesn't blink disconnect the pickup coil connector at the dist and see if it generates an AC voltage when you crank. That's what tells your IG module to ground (fire) the coil.
Test first, don't just throw parts at it.
Test first, don't just throw parts at it.
Fleet Mechanic
Joined: Dec 2007
Posts: 1,512
Likes: 340
From: Wildwood Pa
The electronic ignition on these trucks has both a module on the fenderwell, & a pickup coil in the distributor. When the pickup coil goes bad, or is going bad, it causes all sorts of problems. They are not expensive, but you have to remove the distributor, remove the gear, pull the shaft out, to replace one. Scott