HELP New Lift Pump Preasures

[JTBMC]

Help, I installed Ray's banjo bolts and a new lift pump. The new pump does not sound like it is preasurizing untill you cycle the key 5 or 6 times it runs weak and then it kicks in and preasures up but only to 11#s Inlet Reading taken on top of filter can thru Ray's tapped banjo bolt. What preasure readings should I see from this pump. Cummins say's its ok

Inlet 11#s

Inlet Idle 9-10 WOT 9#s

outlet 7. 5

Idle 6-7 WOT 2-3#s

Ray's Mega Banjo Bolts are Great

Lift Pump Manufactured May of 2001

Cummins part # 3990105 Fuel transfer pump w/ part # 4025182 wiring harness



Oh Yea I've used the different gauges just to make su re gauges werent wrong and all read the same.

THANKS, TJ

 

[Evan A. Beck]

Could be a bad pump right out of the box. I have installed a ton of these things, and about 1 out of 4 is bad. You could also be having a problem with your overflow valve... If it is opening to soon, you will have low fuel pressure.

 

[Archive]

Evan makes a good point... another NW BOMBer is on his third lift pump... the 2nd one was bad right out of the box. New is not always better.

 

[JTBMC]

Evan

How do I test the over flow valve? Is a part of the lift pump or is it a part of the fuel filter canister? Or is it in the VP44, Also is there a way to bench test these pumps. Because I intend to carry this one back to Cummins Mid South even though one of there mechanics told me pump preasures across the filter on the outlet side down to 5 #s is OK. Dodge says Min of 9#s on the out let side I think.



Aslo is it possible that the larger diameter banjo bolts could give a lower presuere reading with a larger volume of fuel being delievered.



THANKS AGAIN, TJ Laffite

 

[Evan A. Beck]

THe overflow valve is the banjo bolt on the outlet line on the injection pump. It takes a 3/4" wrench to remove it. To test it, stuff the threaded end into a hose, and clamp it tight. Apply regulated air pressure, and it should start to open around 11 psi, and be fully open at 12-13 psi. If it is stuck in the open position, or opens too soon, that can result in low fuel pressure.



I am currently devising a way to bench test the pumps, but is is going to be fairly difficult. You have to mimic the fuel filter, banjo bolts, and the VP44. Might just be easier to install the pump on the truck and see what happens. Only takes about 20 minutes to change the pump, so I guess it's not too bad.



I am going to re-locate my pump on the side of the frame rail. I am going to build a special bracket, and insulate it from the frame to prevent it from making too much noise. Getting the pump lower than the tank is going to be the key. This way you harness the power of gravity as an aid in pumping the fuel. Less work for the little lift pump--won't have to suck fuel up above the height of the tank. I'll post results soon!

 

[B. Gill]

TJ actually you can visually check the valve it is a banjo bolt when you look from the threaded side you can see a ball in there and a spring behind it. by blowing air thru it you can see if it is open or not or another way is to stick something from that end and push to see if the spring works.

or might as well just replace if you think it is bad

just my 2 cents

bob

 

[JTBMC]

Thanks Guy;s

I'm Getting on it now and will post later as I've got to make a

190 mile round trip to Cummins for parts.

Evan, yesterday I was able to change pump and have a beer or two in exactly 28 mins, I used my wifes kitchen timer, that includes walking to the ice box.

TJ