Alrighty, so I just moved way up north to Washington from Texas. My lady and I moved up here to be closer to her family and better opportunities, well theres been an agreement on me and my lady's grandfather, Del, he has 1989 F150, 4x4, Single Cab, Swb, with a hopped up 351.

So Del has been telling me the problems on this truck and it kinda has me lost diagnostically but I do want to ask questions about this darn thing. Del decided to take the old 351 block out did some work to it and put it back in. Well shortly after he started to experiencing weird problems with it. When you turn the key into the on position, the fuel pump runs constantly and will cause the truck to not want to start. He replaced the the fuel pump and something else I that I cant remember.

It'll run strong for a little while and start having problems, Del unplugged the battery for 10 days, hooked it back up and it started right up. Once again, it would run strong for a good bit and then just die. Well I got to put my hands on it and all I did was unplug the fuel pump relay, turned the key on, and the fuel pump never made a sound. I connected the relay back in, turned the key, and the fuel pump run constantly and not start.

My guess is that I need to probably backtrack that wiring and check for a bad ground? Any help is appreciated!

If I left anything out, i'll try to update this.

 

Your 351 is likely a Windsor motor given the year of your truck. This is the 335 series form for 351 Cleveland 351M and 400, These are completely different engines.

 

Wrong forum.

 

As stated in your other thread,

I'm pretty sure your in the wrong forum..

try here,
https://www.ford-trucks.com/forums/forum28/

and is that a 351M or a 351W?
I'm fairly certain its a 351W so try here,
https://www.ford-trucks.com/forums/forum55/