I'm working on a 87 D350 for a friend. It will spin over good but will not fire as soon as the switch is released it will try and hit. Thought the switch (electical switch not the key) was bad and changed it but still did the same thing. I know the truck runs because it started one time doing it like I said. Could this be the start/run relay if not any ideas?

 

The problem could be a lot of things including the start-run relay. On the relay you should have 20-30 ohms resistance between pins 4&5. Do you have spark at the plugs? Do you have fuel spraying into the carb when you give it gas? You have dual pick-up coils, one is for starting and one is for running. The start pick-up coil may be bad. Check the resistance of the pick-up coils in the distributor (150-900 ohms).

 

It has only 1 coil. Yes it gets fuel. It ran yesterday but only hit as I let off the starter going into the run position with the key. Will not hit a lick while starter is engauged.

 

I am not talking about the ignition coil. The coils I am referring to are pick-up coils inside the distributor. They take the place of points. 1974-84 had a single pic-up coil and 85-87 had dual pick-up coils. It sounds like the start pick-up coil is bad.

 

Yea sorry about that I figured that out when I looked up the parts. If it was bad would it work some times and not all the time? I don't do much ignition work so I'm stuggling here.

 

Usually when they fail it just won't start. You said it started once just when you let off the ignition switch. When you let the switch go from start to run that is the signal that switches from the start pick-up coil to the run pick-up coil. It sounds like it started on the run pick-up circuit. It may have been a fluke. Take the resistance measurement and you will know for sure.

 

I checked the pickup coil as just as you said one side was dead the other tested 288. The owner said he was going to get the starter relay when he got the pickup. Thanks for the help I never would of thought of that. Will post update when the parts get in and have a nice day to work on it.

 

Good luck! Glade I could help.

 

I finally got all the stuff and time to work on it. After replacing the pick up coil it would start but did spin over quite a bit before doing so. I went ahead and replaced the cap and button while I was in it. When replacing the coil I broke off what looks like a resister? It was connected to the coil and grounded to where the coil is bolted. Anyone know what this is so I can get another one? Also where is the timming tab so I can set the tinning. Thanks for the help it does run now.

 

If you are talking about the resistor looking thing that is attached to the ignition coil it is there to cut down on electrical interference from the ignition into your radio. You can get one at any audio store or radio shack. The timing marks are on the drivers side of the vibration dampener near the top.