1996 7.4 mpi efi VST tank Pump porblems
 

well im back again i got the water in the fuel tanks out and cleaned the injectors but i think the water did something to my vst tank electric pump , i works intermittely , usuall when i turn the motor off when fishing and go to start iit it wont start when i turn on the key so the motor isnt getting gas to the fuel rail but if i tap where the motor is in the vst tank it starts, this happens alot , that it wont start untill i tap it , the motor has only quit when in operation once , then i tapped the vst tank and it started any ideas would be appericated thanks james

You could have a bad fuel pump motor. Basically the motor has 8 or 12 coils that energize one at a time to move the motor slightly. If you lose one and then stop on that coil it will not start back up, until you tap on it and it moves slightly to the next coil. You can put an analyzer scope on it and watch each coil pull power, except one or two. It will still run but is actually turning slower because of the dead field.

Right on sounds good to me
 

Do you know if their is a aftermarket source for these motors or know anyone that will sell a good used one , ive heard people converting to one fuel pump and getting rid of the vst tank how does that work out ?

is it possiable that the water in my tanks before i cleaned it all out and had the injectors cleaned , did maybe the water damage the pump to cause this problem , and i also took out the needle to clean it because it was stuck up in the seat , i sanded it with emery cloth to clean it up so i would go in and out smoothly could the needle be getting stuck ?

I had a similliar issue with my 96 7.4 efi. It would run fine for a while, shut it down, sit for a while and it would usually start but die upon throttle. It would then have trouble starting after that most of the time.

I found the vst to have gunk in it. I cleaned the screen, tank and new o-rings. It solved my issue.

cool ill try that thankyiou

You can do this by plumbing a high performance fuel pump and then run a return line from the fuel pressure regulator to the tank. It works well and will also virtually eliminate vapor lock.