Electric in-tank lift pump?

[Russell]

Can I run a stock TBI gasoline fuel pump as a lift pump for the diesel fuel? I'd like to bypass the mechanical pump, and mount my primary filter back under the truck by the fuel tank (Suburban 42 gallon fuel injection tank), then move my secondary filter out from under the intake and somewhere more accessible...

 

[MaxPF]

I don't know. Diesel fuel does have a higher viscosity vs gasoline, although it still flows very easily. You can always give it a try. The only thing I do know is that TBI pumps put out 12+psi, so you will need a fuel pressure regulator to drop it to around 6psi or so. These are commonly available for gasser apps - just look in a Jegs or Summit catalog.

FWIW the 6.5's with the electronic DB4 pump used a frame mounted electric pump, and they are relatively inexpensive. That would be another option. All you need to do is replace your in-tank electric pump with a pipe and anti-vortex inlet (or an entire in-tank sender assembly from a diesel 'burb)and put one of those pumps on the frame rail near the fuel tank.

 

[Russell]

Would it hurt the injection pump applying 12 PSI to it instead of 6? I can see why that would be a problem with a gasoline injector where it changes flow rates, by why would a rotary injection pump care?

 

[MaxPF]

I don't know if it would be a problem. I also don't know how much pressure a TBI pump will actually put out, since the throttle body has it's own regulator to produce a steady 12psi of pressure. I would imagine the pump will put out quite a bit more...

My line of thinking is this: why didn't GM use the TBI pump as a lift pump? It had already been in use for years in numerous vehicles before they started using an electric lift pump in the '94 6.5 apps. You would think that if it would work they would have used it rather than specifying another completely different pump for this comparatively limited application.

 

[Russell]

Good point!

 

[guz71]

I know someone that ran his 6.2 like that, he switched from a TBI. He used the computer to run that and the TC lock up I believe. Like I said it works and did not have any issues, but Max makes great point and definately knows what he is talking about when it comes to 6.2's.