Plow truck won't start. Cranks but doesn't fire. Spark checker shows intermittent and weak spark, haven't checked fuel pressure or compression, but pretty sure they're OK. Fuel relay just got a new pigtail last year and new pump and filter so it should be good. It ran OK for a while after the fuel problem was fixed. Now I think I have something else...

Took ICM off and took to Auto parts store, they checked it and said it's good. Put it back on distributor. Put new cap and rotor on distributor.

Checked the oil and there seems to be some fuel in there, might be due to me trying to start it a lot in the past couple weeks.

Any ideas where to start? I have some basic mechanical skills but if anyone can narrow it down I would appreciate it. I don't know where to start.

 

is the truck fuel injected? if so check your iac, you may just need to clean the carbon out of it and the throttle body. if it's carbed, adjust your choke and clean the carb

 

It is fuel injected.

What about the spark? I forgot to mention I put a new coil on, still weak and intermittent spark.. Could a fusible link be the culprit or what?

 

Ignition module on the dist is most likely your problem.

 

But I already pulled the Ignition Module (ICM) off and had it tested at an auto parts store. It tested good.

 

Oops sorry i guess i missed that. Did they test it a bunch of times to get it warm? Autozone tested a module for me and said it was good,but when it died and i changed it out it started right up. I always carry a spare in the glove box. Did you try spraying a lil starting fluid in the tb to rule out a fuel problem? Only other things it could be ignition related is the pickup coil in the dist, or low power to the coil.When you turn the key to run does the check engine light come on?

 

Yeah, they tested it 3 times.

I did spray some starter fluid in the throttle body intake and it still just cranked and didn't fire...

Yes the check engine light comes on when I turn the key to run. Is that good or bad...

 

I was thinking about getting a new distributor. If it's the pickup coil I don't know how hard that is to change, might just get a whole new distributor. Does anyone have any suggestions? I looked at the MSD.... Don't know if the cheaper ones are reliable... or if the MSD is worth the extra cost.

 

have you pulled your plugs yet? if not do that and see if they are wet, that will also tell you that you have fuel to the plugs, also might be a good idea to change the plugs while you are there. Some times fouled or faulty plugs can give you some of your problem, i would pull them check, and probally replace to rule that out.

when you checked for spark did you check at the end of plug wire? i am assuming you did, if you have a bad wire may give you a issue as well. When you pulled the ICM off (havn't looked at the 5.8 myself) did you pulled the dizzy cap? If you did was it clean not corroded? check for cracks, sometimes not even that visible so may be there and you not know it. also any connections(electrical) by the dizzy pull apart and clean them making sure to have good contact.






(i belive i have this correct on the compression, others may chime in)
you said you have some mechanical skills so perhaps you checked this most of that already. oh one more thing i just thought of, if you have a really corroded plug(lots of carbon) spark can jump to the carbon under compression and not ignite your fuel so that is also something to look for.

 

Thanks. I did buy some plugs and new wires but haven't put them in yet. Not the easiest plugs to get to. Not much room in there... I will keep you posted if I can get this solved...

 

3 times isnt enough to test that icm. I would try a different one before i pulled the dist. Is yours a motorcraft or did someone change it out? In my experences on dealing with ignition issues 90% of the time its the module,the other ten% its either coil or the pickup in dist.

 

I don't know what brand it is. It's grey is all I know. Would that be a motorcraft?

 

Keep testing that control module. I was having a situation where it would crank and fire and even start, but it wouldn't run for more than a second or two. Just enough to rev it up once. My module tested good...3x. I made the guy hit that button a dozen or more times. FINALLY, it started acting up. Truck did great after a new module. Of course, that was after putting on a high pressure fuel pump, cutting off the cat, and a then a tow home, because after all, the module had tested good!

My gray module was a WELLS.

 

Check post#9 in this thread: https://www.ford-trucks.com/forums/1...-stranded.html

I think you need a black ICM module, not gray

 

He needs the gray one.