I am new to the Forum and I have heard a lot of great things about the wealth of knowledge this forum has to share.

I recently picked up a 89 F350 2wd 7.3L IDI with the 3spd trans. it also has the gear vendor under/overdrive add on and the banks sidewinder turbo package. The truck has 76,000 original miles on it.

Problem:
When the fuel gets low the engine surges a lot. I can not figure out why this is happening. The truck is also burning a lot of fuel. Way more than I think it should. I have not actually checked the fuel milage yet but, my pocket book can tell you it is not good. I am hoping someone on here can give me some sound advice.

Also, I am not used to this gearvendor and if anyone has some information about this it would be greatly appreciated as well. I called gear vendor and they told me not to turn it on unless I am going over 45 MPH.

other than the issues and concerns i have listed this seems to be a solid ride.

Thanks!
Trent

 

I would bet that you need a lift pump, fuel pumps don't seem to like sitting around. Start by changing the fuel filter that is the first thing you do when a diesel is acting up.
as for your mpg you need to check it, running right it should get 10-14 range.

 

Red454 is on the trail, your not getting enough fuel to the engine, unlike gas when they run lean they go, but diesels need full fuel and no air, the mechanical pump should be enough but when your tank is low you have this problem, I would check all the fuel line replace the rubber ones, they crack and let air in, you should pull your sending unit and make sure the last inch of pick up tube didn't rot off. Return lines not that big or a deal its low pressure and would leak if there is a problem, allways check the line that mounts to the pump they are known for sucking air, it's in a tight spot but I have seen that cause most fuel related problems.

 

Your Cone of Failure has failed so when you get to the last 1/4ish tank of fuel you're sucking air:

https://www.ford-trucks.com/forums/1...l#post12907382

VERY common.