What is this bypass idea from superduty.

 

I am going to pull of the top pump and test the bottom to see if it is restricting the perfomance of the in-tank pump. I am only doing this for my own knowledge if it is good info and it helps anyone else great. I am not trying to sell anyone anything. I just had two pumps that were free and I wanted to see what would happen. If the numbers get better with the top pump removed I will certainly leave it off. But if they are the same I will leave both on. My thinking is if two pumps are working in series they will each be working less to accomplish the same task. The good thing is now I have a gauge to see how much fuel is being delivered to the injection pump. I hope you guys like this info and it sparks some new ideas so we can all gain longevity and hopefully some more free or cheap horsepower from such wonderful powerplants "The mighty Cummins diesel engine".

I got the dealer to install the in-tank pump by simply asking. It is much cheaper for them to just do the fix that should have been done during the design/ build phase rather than having to tow the truck into the dealer when the filter housing lift pump dies.

The lift pumps are tested as stated on an earlier post. To me the funny thing is the pump is tested by cycling the key and measuring output after the truck has been sitting, not always at operating temp. The flow test should always be done immediately after the vehicle has been driven and has attained operating temp.

 

Leadfoot,
You are blazing a new trail, don't let the "nay sayers" detour your efforts. Great job, keep it up. I agree with your idea of two pumps working together making things last longer.

Can you tell me how easy it is to bypass the filter side pump?? I take it that it is just some plumbing that was supplied from the re-fit kit???

 

Here are the numbers after removing the top (filter housing pump).


---------Idle------------Cruise set@70mph--------- Lowest PSI (under load)
----------8---------------------7----------------------------2

This the testing was done with the in-tank pump only with filter housing pump removed and everything reinstalled as the dealer had it after installing the in-pump tank. Testing was also done with 5" exh. BDDL on Extreme and about 110gals of fuel onboard. 10 gals. less I had previously for the other testing.

When the dealer upgraded to the in-tank pump a small adapter plate was used with a banjo fitting that bolted directly to the back of the filter housing. Up to now all I have had to buy to do all of this is the gauge and hose so that I could evaluate the performance of this modification. I hope you guys like this stuff.

 

Clearly you have more pressure to and from the filter, so you are getting better volumes from the series setup. (I would suspect that this higher pressure in the high engine speeds would assist in your top end performance helping keep the Fuel Rail closer to max pressure, but not too much on the bottom end as the demand isn't there yet. For reference, the guys with the fass are seeing 15 psi right to the red line. A buddy with a stop watch could tell you if your 0-60 or 1/4 mile are better and therefore you have more power.) In theory, if you want maximum volume, the pumps should be in parallel, or one may act as a throttle for the other. This is of course based on the assumption that in parallel they can put out the same or equal pressures, held at 17.5 by the primary regulator. (I understand that this probably won't happen with the fuel tank back inplace, so I only throw this in for conjecture. But it would be neat!) Thanks for the data.

 

I installed an in-line holly "electric blue" on my `01, this is after the dealer installed the one in the tank as an upgrade to the failed motor mounted one. The tank pump will not supply enough fuel thru the Holly pump to sustain the motor at idle. Try your in tank pump with out the motor pump running at road speed. It may not supply the fuel required to make it go.