Just recently purchased a 1989 Ford F250 single cab shortbed truck. Has a 5.0 V8, a five speed manual trans, and is 4 wheel drive. Bought it because it has no rust, runs and drives and cost 700$. WHen I test drove it, I did so for about 25-30 minutes. Tested all gears, brakes, downshifted and took note of how every shift felt, everything was great. Ran fine but had a small misfire. Started it the next day just fine. To get rid of the miss I bought MotorCraft SP502 Platinum plugs, after I swapped em, the truck will no longer turn on. Here's where the problem is.... THe truck has an edelbrock 4 barrel carb. Looks like a 1407/1406 I think. Almost all of the EEC engine electrinics have been deleted. It has a GM HEI distributor. I pulled the cap and it looks fine, I've tested the coil, and I get strong spark on all eight cylinders, carb is pumping gas like it should, engine wants to start, but will just backfire. When I removed the wires, I did not take a picture of how they were on. I have tried the firing order for a HO 302, and for a non HO 302, I have even Tried both clockwise as I have counter clockwise (Don't know much about GM electronics lol) I have even tried the firing order for a SBC just to try with no avail.... ODnt know what to do, I have fuel, air, and spark. Should I just junk the GN distributor and just go full MSD? Or how can I fix this problem I have. I also have ensured TDC with ignition rotor many times. Don't know what happened. Great truck for the money, I just somehow broke it.

 

Why does it have a GM distributor in it?

And I feel like platinum plugs may have been over the top. I generally go with whatever was OE for the truck.

I would not go MSD unless your building a race truck.. this is an 89 baby 3/4 ton. no reason to throw fancy things at it without a true diagnosis.

You have fuel and spark. what about compression? thats what happened to my 93, had everything running great during test drive then soon after i hit your problem, turns out I had a hole in a piston.

 

Unfortunatly the previous owner installed a Gm style distibutor because he claimed the Ford EEC system wasn't working properly. I personally wish the Ford factory equipment was still there, as I am very familiar with it's operation, and diagnostics. The new distributor is all Ford Down low on the shaft and gear, but the top is GM style HEI with coil mounted on top. Have done multiple inspections amd tests. Definatly have spark. Just sounds like the firing order is way off, won't start now. Right now, I just want to get her running again as cheap as possible, and I doubt I will find a whole EEC system, intakes, and TB very cheap. As for compression I will check wet and dry #'s tomorrow after work. Just seems odd I would lose compression so quickly after a good test drive without beating on it or anything like that. SHe was just purring until I removed all of the wires and changed the plugs. Really wish I had taken a picture of how the wires were on before I removed them

 

The firing order should be 1-5-4-2-6-3-7-8. The rotor turns counterclockwise. The cylinders are numbered starting at the front 1-2-3-4 on the passenger side, and starting at the front 5-6-7-8 on the drivers side.

Line up the mark on the front pulley to near the 0 or TDC mark. Look where your rotor is pointing on the distributor cap, that will be either the #1 or the #6 position. Take a guess which and route your wires accordingly, counterclockwise.

 

88N94. I do know what the firing order is. Like in my first post, I have tried both the HO and non HO firing order. I tried them first counter clockwise like it's supposed to be, and no start, just a small backfire and just cranking no start. I then tried it clockwise just to see, same result. I do not know why she wont start. Have spark and fuel confirmed. I am pretty familiar with the small block ford, have owned many, and have changed plugs and wires many times. THis is the first time I have had this issue. Don't know if it's because of the GM style HEI distributor.... Don't know much about this type of ignition swap. If this was EEC IV or newer EEC I would have the truck running lol

 

I would just pull the GM **** and put ford back in... this just seems like a bad deal.

 

I assume you haven't turned the distributor? I assume the spark plugs you installed have the same taper on the bottom, so the compression can't escape?

If everything is correct and you have fuel and spark, you may have too much gas in the cylinders(flooded). I would remove all of the spark plugs and crank the engine over to get the excess gas out of the cylinders. CAUTION IF YOU DO THIS. disable the ignition system by removing the rotor or something so you won't have spark where the gas is flying out of the cylinders. You could have a fire.

 

Chrono16, although I very much dislike the GM ignition swap, the whole setup looks like it was done very professionally, eveything is clean and tidy. I know you can't read a book by it's cover, but the carb and distributor look brand new, as do the wires. My only problem with going back the ford ignition, is obtaining the intakes, throttle body, MAF sensor, IAC, EGR, fuel pump, and the ford distributor with coil and mudule in a timely and cost effective manner. In my area those parts are becoming rarer and rarer by the day, few vehicles if any have all the components I need to do the re swap, and the people with those vehicles don't want to part out their truck (can't blame em, as I would not want to either). I think MSD would be the easiest, and possibly cheapest option. But I was just wondering if anyone has any experiance with this GM HEI distributor swap, and could shed some light on my situation, so I don't have to drop coin on a whole new ignition system

 

88N94, the MotorCraft SP502 plugs have the same taper, I compared them to the Autolite #25 plugs that were in there from the previous owner. Now that you mention the taper, I will pull the plugs again to double check none of them are damaged, I will then do as you prescribe to see if the carb is flooded, didn't smell like it was, but I will definatly give it the ol college try. I appreciate the tip. I will do this, and wet and dry compression test tomorrow after work. I will keep this updated as new results arise. Many thanks

 

And I have also not moved the distributor at all. I gave it a push to see if it would turn, and she's in there nice with the hold down bolt.

 

Decided to pull cap again...... Noticed there was 4 clips that retain the cap, as opposed to 3, like I thought.. Soooo, stupidity definatly causes a truck to not run. Put cap on SECURELY and properly this time, with non HO firing order starting with 1-5 ending in 7-8. Fired right up, no more miss. Sounds like PO had a wire crossed, and possibly he did not have fourth latch on all the way. Definatly feel like a ******* now . Took her for a spin, runs like a champ and sounds great, a AC gets chilly too. Best 700$ spent to date. *Knocks on wood*