I have a 1988 Ford F250 4x4 regular cab long bed. I swapped a 460 big block and zf5 into the truck. I was orginaly getting a very bad back fire off the 460 so I swapped out alot of parts during the spring and now the truck will not start at all. It feels like while you are cranking the motor over some body has a breaker bar and socket on the cam and holding it down and not letting the truck roll over. Its almost as if it is fighting its self to crank over because it has so much pressure built up in the cylinders. Where other times the truck will crank over perfectly like it has no issues but will never fire, and than sometimes it feels like the battery is dieing and there is not enough power to turn the motor over.

I am at lost of what i can do to get this truck running. Some of the new parts that i have replaced are battery, positive and negative cables, starter solenoid, starter, starter cable, computer, iac motor distributor, cap, rotor, wires, coil, plugs, thermostat, radiator, icm, tfi, coolant temp sensor, and tbp sensor, ecu and fuel pump relays, fuel pump, fuel lines.

Yet I cant get the truck started. I am tempted to cut my losses and almost scrap the tuck after owning it for 6 plus years.

So if any one has any clue whats going on or can give me any advice it would be very appreciated.

Thank you

 

Check your timing. Find TDC on the compression stroke for cylinder #1 and see where that lines up with your timing mark on the harmonic balancer. Then pull the cap off the distributor and make sure rotor is pointing at terminal #1 on the cap. Maybe the harmonic balancer slipped and the timing mark is way off. That seems like a possibility if you had a lot of backfiring and the engine is hard to crank / won't start.

You can find TDC on compression by removing the sparkplug and stuffing a wet paper towel over the sparkplug hole. When you're on the compression stroke, the paper towel will pop out.

 

Thank you mark1986f150,

I checked my TDC and looked to see that my rotor was way off. So I pulled my distributor and re set the rotor so that it was pointing at terminal #1, set the distributor back in the truck. She fired right up, no back firing and she was idling pretty well. Thank you for all of your help.

Now I can finished fine tuning the motor and get ready for truck pulling season.

 

AWESOME! Glad it worked out and saved the truck from the scrap heap.

When you set your base timing, be sure to remove the SPOUT connector. If it's like the other engines, it should be set at 10* BTDC.

 

Sounds good to me thank you again.