Truck background…high mileage 97’ 350 with a 460 out of a ‘92. This is my boyfriends truck and he does 90% of the work on it, however we had a shop do the engine swap as he was sick at the time.

She ran fine with no problems until we pulled it into the shop to put new brakes on the back. While it was in there he replaced the rear fuel tank. Since then he cant seem to get fuel to the motor and has become overly frustrated. It’s about to be towed to the shop but you guys are very knowledgeable and this seemed a logical way to proceed before spending a ton of money. Here’s what we know…..

The fuel pump pushes fuel through the line forward (both from the new tank and the old one) and you can manually blow air through the line backwards so the line isn’t clogged. He’s replaced the fuel regulator, maf sensor, all of the relays for good measure, and checked all the fuses. He of course replaced the fuel filter. He tried using a different ecm from another 97 but it made no difference.
Any suggestions would be greatly appreciated. I’ve been reading about the difference between speed density and MAF and I’m curious if this might be the culprit as he didn’t do the swap himself and we are unsure of what all was changed. However, I was told that’s unlikely since it was running fine for 6 months to a year prior to the problem arising. I don’t think this truck has a fuel pressure valve, I checked the emergency shut off but shouldn’t be that anyway since pumps are running, and my boyfriend replaced the injectors.
He was able to start the truck on starter fluid momentarily to confirm it was a fuel flow problem.

Forgive me for not being able to give you a better description as I am not that mechanically inclined. My boyfriend will be helping respond to questions/answers when he is home from work this evening. We just found out the shop had a cancellation so I’m just trying to get this out there as we don’t have much time to decide whether or not to send it in. Unfortunately this would not be the same shop that swapped the motors.

thank you in advance!

 

If it ran for 6 months there isn't an issue with the engine swap, it's much more likely the new fuel pump is the issue. What fuel pressure do you have at the engine? "some fuel being pushed" isn't specific enough.. the motor won't even start with 10psi... it needs 40psi to run correctly.

 

im sorry I thought I added that part, after starting it on fluid to make sure it was a fuel problem Kellen checked for fluid at the rail and there wasn’t any. Also each tank has its own fuel pump and the truck won’t run on either one.

 

Does the selected pump turn on when the key is turned to RUN?

 

Ask your BF if he had to splice any wires when replacing the fuel pump? It will run with the wires reversed but will push fuel back into the tank instead of out of it.