Well hello again, it’s been awhile!

Truck has run really well after diagnosing alternator wiring harness issue year ago or so. If you remember I ended up going to 3g after replacing just about everything in the charging system along with new carb due to it stalling at lower rpms. I had a huge thread on here about ground wires, lights pulsing, and stalling…

Anyways, fast forward to now. My truck is turning over and not firing. Not really sure where to start with this as I know the battery and starter (starter is about a year old) are fine. Almost sounds like it doesn’t have fuel. But I know there’s gas in it. Usually my truck only needs one press of the gas pedal and it fires right up. Now it’s turning over strong but not firing. It did this last week and tried it again the next day and it did start and I let it run for about 10 minutes. This week no fire.

84 F350
460 4x4

 

Alright… so after I posted the thread it took the air cleaner off and manually pushed the throttle thingy (what do you call that?) to see if fuel squirted into carb. I couldn’t see it but heard it. Turned the key and fired right up.

I then shut it down and few time and started it again and it was fine until about the 3rd try. Now it’s just turning over again and not firing. I tried squirting more fuel in manually with the air cleaner off and still wouldn’t fire. Tried again about 5 minutes later and it fired with some belt squeak… which I haven’t heard before.

Heres a photo and video of it running.

 

You can go to harbor freight and get a spark checker pretty cheap.

https://www.harborfreight.com/in-lin...=spark+checker

 

Forgive me for asking, but what are some reasons why I might not have spark?

Along with everything else I did last year I did a full tube up. Wires, cap, rotor, plugs, etc. All my grounds were checked and redone as well.

 

Dose that MSD use the factory IGN box or is it RTR / no box needed?
So could be bad pick up coil in the dist.
Bad coil and / or coil connection.
Bad IGN box if used.
Bad rotor under the cap making spark go to ground.

You need air, fuel & spark.
You have air when its cranking
I would recheck (see not sounded like) the fuel in the carb. Can try a little starting fluid or pour a little gas down the carb.
Check for spark into the dist and at a few of the plugs.
Dave ----

 

Sounds to me like you are flooding it.

 

Factory IGN box.
Cap, rotor, wires, ignition coil were all replaced last year.

 

So you replaced the Ford DS II dist. for a MSD one, why?
So have you checked for spark?
Spark / fuel / air is all that is needed to start / run remove 1 and no go.
Dave ----

 

No, I didn’t touch the distributor. Just the cap and rotor. The ignition coil was also replaced. The only thing that makes sense is probably the IGN box.

 

Maybe but you have not told us you dont have spark you are just guessing and throwing parts at it.
Now its not my money so if you want go for the IGN box and see if it fixes it but if not you will need to dig deeper to find the cause and fix it for good then.

Oh just because you replaced parts with new ones dose not mean they are good, another reason you need to check things before guessing and trowing parts at it.
Take that "new" coil wire from coil to dist. looped under the coil. What if it is shorting to ground? You now have no spark but you replaced it with the other wires so it must be good right?
Start at the plugs for spark and work your way back to the coil. If you dont have spark at the coil check if it is getting power to 1 side, the other should blink a test light when cranking.
If you dont have that you will need to dig deeper.
Dave ----

 

I would always keep a spare ignition box under the seat just in case. So if it turns out to not be the problem, I would keep it and throw it under there. They do like to fail on occasion.

 

True that I just replaced mine even that it was working.
thought it would fix another problem that pointed to the box, no way to test before the replacing.
BUT the old box was also leaking the potting, another reason I thought the box was going bad.
The sticky mess was running down the inner fender and dripping on the floor of my garage
I do have another box on the spare fender I should put in the truck just in case.
Dave ----

 

Does that fuel filter have a arrow on it? And its pointed the right direction? That looks odd to me.

 

Thought I’d update you all. I replaced the ign box and it was not the answer. Every once in a while the truck will start right up but but most of the time it just cranks.

Truth be told I’m not very good with diagnostics. Which is why I tend to throw parts. But here’s what I’ve seen so far (via YouTube help).

I don’t think I have spark at the plugs. Although by the time I pulled a plug to look my battery was running low and it wasn’t cranking as well. Not sure if that matters?

I also checked the voltage at the coil. I put my meter on the hot side of the plug (had to disconnect it to get the prong on to it) and the negative on another piece of bare metal. The voltage more or less matched what I got from the battery (a tad less). I think I did it right?

Anyways I’m not sure what that means or what to do next.

 

The check light Franklin2 posted is probably the easiest route for you to check your spark. I have never used this product. I usually either use a timing light if handy or will pull the plug and ground it. But the way to use it would be to pull a plug wire and attach this to the plug and then attach the plug wire to the light.

If I were going to do this. I would:

1. Remove plug wire on the driver's side bank.
2. Install Light on plug.
3. Attach plug wire that I pulled off the plug in step 1 on to the end of the light I installed in step 2
4. Prop light so it is visible from cab with hood open
5. Wait for dusk/low light/night (to make it easier to spot the spark plug tester light)
6. Crank motor while eyeballing the test light.

Now if you can get a helper you can have them crank while you eyeball the test light.