have a 1985 e 350 with a 7.5 ltr or 460 gas engine it is carburated and duel tanks we cant seam to get any pressure out of the in tank pumps lots of flow but no pressure when your doing about 50 mph it all of a sudden bogs down and wont go any more shut it off and it goes fine any sugestions would be great ty in advance

 

Welcome to FTE!
Those pumps only produce about 7psi, so you really aren't looking for that much pressure. Does the van have a catalytic converter on it? That may be plugged internally, especially if the van has more than 120k on it. Does it generally feel like a lack of power also?

 

thanks but that isnt the problem it has lots of volume but no pressure it seams and the converter has been removed already so that is not it
it seams to be fine for a bit and then it scts up we have been working on this for almost 3 mnths now

 

I assume that you did not list your measured pressure and volume, it has not been verified yet?

Put a pressure guage on it to verify the pressure, measure the volume, and check the filter and lines for kinking or damage.

As the problem seems to effect both tanks, check the parts of the fuel system that is common to both tanks.

Also I thought that there was a valve that switched the lines from tank to tank and there was a pump on the engine that draws fuel from the tank's (with suction) and the intank pumps were for EFI only and had a return line with a pressure regulator?

If it is suction, I had one that had a small pinhole that would draw air on suction, but would not drip so there was air along with only enough fuel to get up to 50 mph, only with a vary light throttle!

It has been a while since I worked on one that old.

 

The mid-80's 460 had what was called a "hot fuel" option, which was electric pumps in the tank, rather than a mechanical pump on the motor. Vapor lock is virtually impossible with this system, making it good for hot climates.

 

thanks guys got it fixed needed a new pump and relay