jc07874

I have a 97 Ram 2500 with the 12v Cummins.

I have just completed the conversion to veggie oil. I am thrilled how well this works on WVO. It was a nasty conversion of the stock fuel system and I am in the process of tweeking the system and working out a few little bugs.
I have a heated VO tank

I have a selenoid that switches between the two tanks and an additional selenoid that handles the fuel returns to the appropriate tanks.
Everything works like a champ except for this one little thing that I need to address.

The Problem - I can switch from Diesel mode to V.O. mode wthout incident but when switching back to diesel after running on VO for a while the engine spudders and stalls. It restarts again on diesel after cranking for 10 or 15 seconds (much longer than usual).

I suspect either
1) air is getting in to the diesel system when runing in VO mode.
2) The diesel line is over or under pressureized when changing back to diesel mode for a few seconds.

I know there is an electric fuel pump in the stock tank that pushed the fuel to the engine compartment.
I think that fuel pump in the tank that runs continuously when I am VO mode and I supect I am over pressurizing the lines Diesel fuel feed to the engine because the fuel has no where to go when I am in VO mode.

I wonder what I am doing to that pump if the fuel has no exit.

There is some sort of regulator on the top of the tank where the fuel leaves but I was wondering if there is some sort of overflow function to bleed the extra fuel pressure back into the tank. I am wonderin ifthat has something to do with the loss of fuel pressure when switching back from VO to Diesel.

Can you mechanical gods give me any ideas. I don't want to break into the fuel system again witout a plan or a target. It is a very messy Easter Egg hunt otherwise.

I have a fuel pressure gauge but no place to hook itup to see what the tank pump is doing. But I suppose I can rig something.


thanks

Jeff

chop342

Your stock tank doesen't have a lift pump in it unless you installed an aftermarket one. the only stock lift pump that truck has is just below the fuel filter assembly mounted to the side of the engine block with the fuel heater right next to it. i think the truck just runs out of fuel for a second when switching tanks. i would install an electric pusher pump or lift pump inline on the diesel tank before the tank select solenoid. and have that turn on when you switch back to diesel from burning WVO. or install a one way check valve in the diesel line before the select solenoid to keep every bit of fuel prime you can and i bet that will solve your troubles.

Chris

jc07874

**** .. That sounds like a plan. I can put it right by the dino feed on the selenoid. DO they have 5/16 check valves that work ok in a diesel line? Am I going to an autoparts store or a plumbing supply?

That sounds like a cheaper alternative than a diesel fuel pump. Besides, I would hate to add another point of failure in this already over-plumbed fuel system. Already feel like I am tempting fate by screwing with such a greate engine design.

Thanks..

Jeff