I recently bought a 1990 f350 with a 460.

When the weather is cold I have no problems with the EFI. When it gets 90 degrees or so I find that when the gas tank either front or back gets down to 1/2 full it acts like it is running out of gas. I switch tanks and it will pick back up and run ok. It will do this on both tanks.

Someone said it could be the fuel pump. I have replaced the regulator and the control module. It seems to start sputtering when I slow down from a high speed to turn a corner. Could both fuel pumps be bad.

Like I said it happes with either the front or rear tank. As soon as the sputtering starts I switch tanks and it seems to grab and run fine.

Any ideas would be appreciated/

Thanks.

 

You could have bad in-tank pumps. Does your truck have a high pressure pump on the frame near the filter? If so, then it is possible that the low pressure pumps in the tanks are not feeding the high pressure pump on the frame. The high pressure pump does not suck well from the tanks which is why it requires the in tank pumps.

 

I will check that out. I know there is something by the filter. I thought it was the device that switches between tanks.

I also figured out that scince I do not have a tailpipe on the truck that the exhaust from the muffler blows back on the back tank. That cannot help things.

Thanks.

 

If you have the selector, then you should have the on frame pump. It will be next the the filter with a single in and out line. The selector should have 4 or 6 lines on the tank side for supply, return and vapor I believe. It does sound like the tank pumps are not working properly to keep fuel pushed up to the frame high pressure pump.

 

From what I can tell there is no pump by the filter. so each tank must have its own high pressure pump.

I just noticed that the fitting for the breather to the rear axle is broken off of the axle. Have you ever replaced one of those?

I plan on drilling our the old one cause I doubt if an easy out will take it out.

I suppose I will take off the differential cover and drain the fluid hoping to get all of the metal shavings out.

Thanks,

 

I never have had to replace one of those. Yes, it would be a good idea to pull the cover and change the fluid after drilling.

It does sound like you have just the two high pressure pumps in the tanks.