Crank, No start
 

Hey all, I have a 1990 F-250 with a 5.8L and ZF 5 speed transmission. I just finished a parts volley of maintenance items like drums shoes drum hardware, new brake booster and master and such, i did have to drop the rear fuel tank for somthing and put it back up when i was finished. I took the truck out for a test drive and everything was fine, then it shut off while i was driving! and i rolled it to a safe spot and im gonna flat tow it later tonight when there is no traffic.
Anyways I tried to start it, and it cranked just fine, but no start not even a pop. My Dad think its vapor lock cause I had the fuel tank off for a week or so. When I put the key on I can hear the fuel pump prime, switched tanks and the other pump primes as well. but still no start. What do you guys think it could be? I'll tinker with it some more tonight when i get it home. What do you guys think?

Check to make sure that you didn't pinch off the vent line when you put the tank back in.

Thanks ill check that

Alright so nothing's pinched all the lines look okay and I'm not leaking any fuel, There are two vent lines connecting to the rear tank they both are good. Truck still does not start im gonna try starting fluid and see what happens

I'd give you good odds that the ignition module on the side of the distributor went dead.

that was kinda my next thought.. I believe it’s called a TFI module? Where the spout plugs into… also heard there was a way to test them I’ll look into that thank you

The TFI module is a possibility. The SPOUT doesnt plug into it, but it does plug into the harness that goes to the TFI

Yes there is a way to test them but I have never done it. I usually just test to see if I have ignition like you was going to with the starting fluid. Sometimes I test to see if I have power up to the coil through one of the small wires hooked onto the coil with the key in run position. Many times I just play the odds and replace the ignition module .

If it comes to replacing the ignition module, you need a special tool a sort of skinny nose socket, most deep sockets aren't skinny enough.

just so we’re clear the TFI and ignition module are the same thing? I’ll run a few tests tomorrow and get back to ya’ll

Yes the same thing by different names. it attaches to the side of the distributor with 2 small bolts I'll call them because they have a 6 sided head, 7/32 inch If I remember right. As I mentioned it takes a special tool because the sides of a 1/4" drive deep socket usually aren't thin enough. After you remove the bolts, pull down to remove it from the distributor.

The Napa near me sells the special tool NAPA SER 3197 is the part number, Gonna pick up a TFI module as well and make sure it comes with the paste. I'm gonna buy the motorcraft one.

Yep the tool I have has the number 3197 mine is a K-D brand I bought it at NAPA around 1995.

If you're going to replace the TFI module, get some actual thermal paste. Most places that sell computer parts will have it. Far too often, the little tube of schmoo they put in the box with the new modules isn't thermal paste, and heat is what kills these modules.

Yea I heard about that, thing is I thought thermal paste was used as a heat transfer like when a CPU is connected to a heat sink with that paste. I’ve heard of people using di-electric too… are you sure it’s thermal paste and not some other concoction?

Di-Electric is a heat insulator. Not a heat conductor. The TFI Module has a metal backplate on it, that uses the distributor body as a heatsink. You would almost be better using nothing at all, than using Di-Electric grease.