High HP OBS fuel system discussion

[Strokeorcroak]

Have a truck with large enough injectors that the stock selector valve and fuel lines were not going to cut it.

The original idea was to use 2 sumps. The rear sump would gravity feed to a T on the front sump, with hopes to keep the 2 tanks tied together as one large one. Then we would return all fuel to the rear tank (because it is higher).

Purchased 2 sumps and all the gear and went to install, a sump will not work on the rear OBS tank.... or at least not the sumps we got.

The sumps we have are 5" diameter on the out most O-ring, the largest we can have is 4" on the out most o-ring to use it on the rear tank.

Question 1: Has anyone found a sump that will work or does someone sell one no larger than 4" diameter on the out most o-ring?

Question 2: Whats another method people are using on the OBS trucks while hopefully keeping the stock amount of fuel on board (one large tank? 2 pick up tubes with a manual selector valve before the first filter?)

Thanks

[BigFuel]

I haven't done this on a diesel truck but I have on a modified gasser. Run each larger supply line from each tank forward to a location on the rail that you can work in. Independently install two (one for each tank) fuel pumps (I'm assuming you have swapped to a E-Pump set-up for your fuel demands). Next a pair (again one for each) of one way check valves (so that the tanks don't just fill each other). "T" and run forward. Keep the stock selector for the fuel return to each tank. Wire the selector and pumps in parallel so that the same tank is used for both directions.

Is this for that 615hp beast? If so then custom work is not out of the question. In this case I'd say screw it and run each tank completely independently from the other and feed one tank to each bank. Then the system would feed 4 instead of 8. Both my tanks are nearly the same size so I would use the sender from the slightly smaller one to run the gauge and a dummy light to the other just in case.

[BigFuel]

Rereading your post, Transflow does make a 40 gallon Mid-Ship replacement tank for our trucks. LMC also sells a 40 rear tank as well but it ditches the spare tire. Both are future plans for mine... ...eventually