okay guys, so I changed out my front fuel pump last year with the spectra premium fuel pump. On the way home from work last night the tank ran out of gas and I quickly changed to the rear tank. As soon as I filled up the front tank I could totally notice a loud hum and now it's filling the rear tank again. Can I just buy the pump itself unbolt the hanger assembly and sending unit? And will that fix the fuel return problem? What do I have to buy a whole new assembly?

I've heard Bosch is the way to go. But I haven't found a part that is the whole assembly, just the pump itself.

 

You didn't say what year your truck is. If its 87-91 (I think) it's probably the reservoir on the frame rail before the high pressure pump. If you need one, LMC truck sells them.

See this: on tank filling the other tank

 

[QUOTE=87-XL-Squared;13511435]You didn't say what year your truck is. If its 87-91 (I think) it's probably the reservoir on the frame rail before the high pressure pump. If you need one, LMC truck sells them.

Sorry, its a 94' with a 7.5l. I see that the Bosch model 67000 is for my truck. So I'm thinking I might just buy two of these, and take apart the fuel module and put these pumps on instead.

does anybody know if the check valve is inside the pump itself, or inside the hanger assembly up on top of the unit?

 

The check valve is not part of the pump, it is part of the FDM (Fuel Delivery Module)

 

And the check valves in the FDM in your rear tank are the problem.

 

what makes you think its the rear module? and an update, the flow is both ways front feeds the rear and rear feeds the front

just weird that it happened after running out of gas and switching tanks. like running it dry ruined something. reason I know is because the rear was almost empty . this didnt start tilk I ran out of gas and filled back up.

 

Maybe you pumped trash into both valves..............

 

Possible but I would still think it's only the front module. The rear wasnt totally empty. But who knows. Time to hit up Rock Auto

 

Because it's usually the check valve in the tank that is receiving fuel that is the problem.

 

That part I get. However, the tank was filled to half full and by the time I got home literally almost all the gas was shoved to the rear tank. with that going on, I would think the front module has a problem because the check valve in the front module is closed and not receiving the returning gas.

 

Both the send and return lines on these trucks are simply Tee'd together so fluid under pressure will follow the path of least resistance.

 

No, the problem is that the check valve in the rear FDM is stuck open so the returning gas goes there instead (another way of saying what Conanski already said)