hey my 78 bronco has been giving me some major issues lately. it'll crank and crank but wont fire. i've checked for spark and it only gives spark the first moment it starts to crank and when it stops. in between those moments it wont spark. i've replaced all the computers and the coil and cap and rotor and even the pickup coil. i'm completly lost. the timing is spot on and she's getting fuel. cranks great and the compression is strong. i'm at a complet loss. someone please help. and she's got a 351 modified.

 

when you checked for fuel did u take a fuel line off and crank it so the fuel runs into some type of container? otherwise you might get a false reading for fuel. also check the intake. idk if this is your daily driver or has been sitting, but there could be a something not letting the good air get into your engine causing it not to start up. it could be a block in your exhaust but it would have to be a extremely plugged cat to do that. still possible though.

just though of something else. im not sure if yours is this way but on your dizzy there's a gear that spins and if that gear is chipped or teeth are broken it could cause it not to send a spark to all cylinders. anyways worth a check

 

ya she's my daily driver. and when she runs, she runs like a champ. but she'll be runnin great and i'll park and shut her down and then she wont start again. sometimes just for a few hours. sometimes for weeks. and i have a brand new edlebrock intake and carb. and ya i've pumped fuel into a mason jar and its good fuel. only a week old. and i know its getting fuel down the intake cuz she'll flood out if i crank her to much. i've exhausted the extent of my mechanic knowlage. i've checked all my wiring and my grounds and everytthing. but i will check my dizzy.

 

Have you looked at the coil wires themselves? Make sure there isn't any parts cut on them. My 78 the PO had cut both wires and twisted them together then taped them up so when they moved at all i got no spark. I would look along there then take the plug wire off from the coil and see if your getting a spark. Then try at the other side of the coil on the dizzy. You may have already done this but thats what i know. I went and replaced everything from the dizzy to the ignition box to the starting module, and then my neighbor comes over and pulls the tape off and resplices the wires for me. I was pissed.

 

Stator, PIP, would be suspect in my diagnosis, easiest path to running good condition goes thru rebuild distibutor with all new electric or magnetic (stator) parts.

 

Check the ignition switch .
Also have the duraspark control box tested .

 

Okay so I have a '96 bronco.. She'll crank and crank but she won't turn over. Fuel pump is new distributors new starters new. I'm not sure if its a fuel issue or possibly a spark issue, what is a goo way I can check to see what it is?

 

its the ignition module on the driver side inner fender well. mine was doing the exact same thing about a month ago. I had a spare module and swaped it out. fired right up.

 

I will second Encho's suggestion. DSII (Duraspark II) modules are known to behave this way when they fail. (And even if you have replaced it, if you haven't replaced the voltage regulator, do that BEFORE you put another new DSII module. A faulty voltage regulator will kill the DSII module in short order.

 

These guys will recommend you do a KOEO test I think. That would probably tell you but the way I do it is to pull a plug wire, cram a screw driver in it then get the shaft of the screw driver close to a metal ground such as a bolt or shock tower brace. Then have someone watch it while you crank, if there is a good solid blue spark you can eliminate that. Then there should be a schrader valve on the fuel rail. You can turn the key on for a few second then off and go push down on that valve. If fuel sprays out with a good amount of force then it would probably be your injectors.

Another thing to check is something called an "Inertia Switch" these are designed to turn the fuel pump off in an event of a crash so you won't have fuel pumping out in case of a fire. Here is a location picture for you to check.

I've been taught to keep a spare of each with me along with a coil. If I'm ever stranded I can check to see if these are no longer working.

 

You really should have just started a new thread for this. The OP was working on a '78 which in no way works the same as your '96...

 

Indeed. With a 96, troubleshooting is as simple as running diagnostics tests. Maybe Mods can split this one out into a separate thread?

 

By mods you ment Encho right? Hehe we need to test his new powers

 

Either one of 'em. I've known Rich (Wheelma1) since I joined and Encho continues to prove his value as an asset to the forums.

 

I've talked to Wheelma1 before but at least in my experience, he doesn't seem very active. Or just doesn't respond very fast. Besides, Encho needs a little more practice with his tools of destruction...