Engine/Transmission (1998.5 - 2002) WHATINHECK is a "Pusher pump"?

[Gary - K7GLD]

A "pusher pump" is an added, supplemental fuel pump that is usually installed somewhere under our trucks as close as possible to the fuel tank by cutting out a small section of the existing fuel line, and inserting the new pusher. It's intended function is to assist the stock lift pumps in our trucks by supplying additional fuel flow and pressure - which in turn helps assure proper fuel flow for operating and cooling the VP-44 injection pump.



Early on in our trucks, this was pretty much the ONLY available option for upgrading/improving the stock fuel delivery system as a means to reduce LP and VP-44 failures - now, commercially available setups like FASS, RASP, and AirDog have hit the scene, and new diesel members here might like to know what started it all...



OR, to know what other, less expensive options are available and in use.



A pusher pump setup can vary from one owner to another, but my pump, including a home-made bypass valve and filter, looks like THIS:



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The purpose of that bypass valve in my case is two-fold - it is designed to bleed off the somewhat higher total system PSI than I wanted, down to a lower PSI, and to also allow fuel to flow AROUND the pump in case the pusher failed. In tests, it has functioned flawlessly!



Here's what it looks like installed under my truck, back near the fuel tank:



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I tap into a keyed 12 volt source to operate my Carter pusher (7-9 PSI model 180-P4600HP, about $70 from Jegs), and that operating voltage is controlled by THIS relay:



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That Radio shack relay has 20 amp contacts, and plugged into a Radio Shack socket that allows quick and easy replacement if needed, or allows the pusher to be shut down for testing by simply unplugging the relay. The relay coil is tapped in parallell with the power lead going to the stock LP, and is controlled by that circuit - thus, the only additional load on that circuit is the coil current draw of the relay, which is trivial.



Some others DIRECTLY wire their added pushers off the same power lead as the stock LP, without use of a relay, but I prefer to keep that added 5 amps or more off the LP control circuit - ECM's ain't CHEAP!



Cummins offers a power lead extender for the stock LP than can be easily wired with the relay coil leads, then installed between the stock LP and the main wiring lead - it's about 10 inches long, costs about $8, and the Cummins part # is 4025182.



My setup has been installed for about 32,000 miles now, no problems, and as far as I am concerned, the $100 or so it cost to purchase parts and install was well worth it as protection for the rest of my fuel system!



Details of my particular pusher and bypass setup can be seen in my readers rigs section under "pusher pump"...

 

[wicked6]

Gary, et. al -



Is there any benefit / drawback to using a conventional check valve in lieu of the "flow control valvebody" you've got on your bypass / shunt. . ??? I like the design. . Simple & effective!!



wicked6

 

[barbwire]

Thanks for all the info & your effort. I am earmarking this thread for later, when I find a warm place to work. Prolly next summer. I for one appreciate your efforts.

 

[Gary - K7GLD]

A simple check valve will only provide a single function, the ability for reasonably normal fuel flow if the pusher fails - in my case, the valve I made provides *2* functions, the bleed orifice thru the valve "flapper" screw bleeds the somewhat higher fuel PSI developed by my particular Carter pusher pump in normal operation - Carter DOES make a pump that operates down in the 5-7 PSI range that probably would not need the PSI bleed function, if that is a concern for an owner.



My pump setup was providing nearly 24 PSI prior to my bypass mod, and after that mod, was down at 20 PSI - maybe not a whole lot, but *I* felt a bit safer at that level.



A future mod, when next service requires removal of my pusher, will be a fuel shutoff valve in the fuel line before and after the pusher/filter setup to allow its removal without a diesel fuel bath!

 

[cap-n-cray]

Gary,



How much noise does the pump make? The pump looks very much like a stock lift pump with out the connector. My lift pump just failed today, 57K. I am in the market for something different.



Cary

 

[Gary - K7GLD]

My hearing isn't the greatest, but I can't hear mine running when the mighty Cummins is alive - but I sure could BEFORE I finally installed that relay so the pusher only runs when the stock LP does!

 

[rwitt]

Great info Gary! What filter are you using before the pusher pump? I'm getting ready to install my pusher and want to put a filter ahead of it.

Rich

 

[rmrc]

Gary,



Nice looking setup and for the price, you can't beat it! Too bad we're on opposite coasts. I'd pay you to put one in my truck. Bad back prevents me from doing many things I did in the past without a flinch.

 

[Huff N Puff]

A real pusher pump should be installed in the tank. A pump can only pump what it can draw through the line. Installing two pumps will increase the pressure,but will not help the volume,in fact you could aerate the fuel supply to the VP44. If a pump pushes harder than it can draw it will aerate and adversely effect the volume.

 

[Huff N Puff]

Sorry Gary,I just thought of another problem with the pictured setup. Your filter will restrict the flow, cause its on the suction side and it will also store a pretty big air bubble. Its an air bubble you cant get rid of cause the tank will surely supply it with more air as the fuel sloshes or runs low.

 

[Gary - K7GLD]

"Sorry Gary,I just thought of another problem with the pictured setup. Your filter will restrict the flow, cause its on the suction side and it will also store a pretty big air bubble"



Well, fortunately, my setup is way too dumb to know any of that - and instead, simply continues to function in grand style!



I guess ignorance IS bliss!



As to the filter ahead of the pump, that is required/recommended by Carter for their pumps in order to keep debris from entering the pump and damaging it... .



As to that filter essentially causing some form of cavitation, or air bubbles - it sorta helps to use a filter with a high enough flow rating as to meet the demands of the pump(s) downstream - and while I can't provide laboratory proof that all is well in my system, it sure SEEMS to be working well in all respects - excellent fuel PSI under all loads right at the inlet to my VP-44 for about 30,000 miles and 2 years now!



SO, about when to you predict my Cummins or related fuel supply system will explode in a puff of diesel fuel?

 

[Huff N Puff]

More Food for thought

Most pump setups use screens on the suction side,because screens are less restrictive. A good test for your pump is to undo the line to the vp44 hook a clear hose to it put it into a gas can and power up both pumps see if you have solid flow of fuel. My guess is it will be pretty frothy. One more thing do it when the tank is slightly low. Other factors that will restrict the suction filter will be cold temps. The filter you are running looks to be a gas filter and is usually run on the pressure side with about 40psi of gas pressure. Putting it on the suction side and running diesel thru it may make it restrictive.

 

[Gary - K7GLD]

To each his own, and everyone is entitled to their own opinion - But I sorta shy away from trying to find problems when it's pretty clear from time and miles there ARE none - and I also follow the "if it ain't broke, DON'T try to FIX it" line of reasoning!



MINE isn't broke (REGARDLESS of what ANY distant individual, who has never even SEEN it, might try to convince me of!), it works well as time and miles have proven to my satisfaction - and there seems to be NO reason because of someone else's imagination or worries, for me to attempt to re-engineer a system that is clearly working fully as intended...



YMMV!