Engine/Transmission (1998.5 - 2002) Banjo ? and idea for a air purge mod.

[Walt-L]

Hi folks,

I'm new to this Cummins game, but a old hand at all sorts of mods. I have a new to me 01 QC SB and have a idea I would like some feed back on. Can I use the same taped banjo bolt for the pump return line fitting(thicker) as the feed line? What I would like to do is first remount the driver side battery side ways and to the front witch would give me a space to the right side of it for 1) relocateing the fuel filter there and sending unit for the fuel pressure gauge.

I would like to come off the feed line banjo to a brass tee tied to the bottom of the sender. Uphill of the horazontal sender I would mount a nice aircraft fuel line ball valve that has 2 1/4" barbs at 90 degrees to each other.

This would be mounted to the tee. then take clear 1/4" fuel line and go from the ball valve to the second banjo in the return line.

Now I would mount a 3 way switch that breaks the power feed to the lift pump AND repowers it from a always hot source when you filp it up and down would return the lift pump to its normal wiring.

What this system would do is WHEN EVER you have air in the system, You simply open the ball valve at the gauge sending unit and flip the near by switch. Wait untill you see no more bubles racing through the clear line, shut down the switch and close the valve and your done.

That "bumpin the starter" thing sounds a little hokey to me although I'm sure thats been OK standard procedure. Routing the fuel line in a up hill fassion to the valve would ensure the sender has no bubles under it for jerky readings.

Well, what da ya think ? (aside from me having too much idle time)

 

[Ncostello]

Welcome to the TDR Walt!! I can't exactly picture what your wanting to do although I think I sorta do. From the sould of it your wanting to replace your return banjo bolt (thicker one) with a tapped banjo bolt. Then you can pump fuel directly into the return line until it runs clear in the clear tube... is that right?



First thing you want to consider is that the bigger banjo bolt on the return is bigger for a reason. It houses a spring and ball and functions as a pressure relief at 14psi. Thats the only time fuel flows thru it except it also has a tiny relief port drilled in it. That tiny relief port allows air and some fuel to bypass the spring and ball to return to the tank. This is what allows the air to escape during the priming process.



So in theory you could just replace a segment of the return line coming off the VP44 with some clear tube and accomlish the same. However I don't know of any clear tube I'd trust under my hood. Most SAE J30R9 fuel injection rubber hose is reinforced and rated at 100 psi working. The short segments of rubber hose Cummins uses in this area of your filter and banjo fittings is 30R9.



One good thing though! The idea of using a constant hot power source is what I do too. I just unplug my LP and plug in my leads that have an identical plug for the LP. Then I hook the alligators to the battery and let it run for a minute or two.



Sometimes this works great and it fires without missing a beat. But I still can get the start... then die due to air in the system. I don't know where the air is but it never came out. Then its the old "floor it and crank for 20 seconds". That always works as long as the system is mostly purged of air.



Hope this helped a little.

 

[Walt-L]

Ncosttello,

Thanks for the reply.

The number on the clear fuel line will be very helpfull. And now I know enough to leave that return fitting on the pump just the way it is! A splice in the metal line looks like the solution. Its a shame Bosch didn't design the VP44 more like the Bosch IP on my VW TDI. That little pump can digest a steady stream of air bubbles in the fuel and not skip a beat! Just off hand, do you happen to remember which wire or terminal on the LP that is the power one?

Thanks

Walt

 

[Ncostello]

I dont remember which wire is which. I'll have to look. On my original LP is was obviously the red one. But the newer (2000 up) pumps have a plug directly on the pump with no wire leads. I'll have to go home and look at my jumper leads. I'll tell you which one if your holding the pump in your hand upright and looking directly into the receptacle plug on the pump.



PS: The J30R9 fuel hose is not clear. Its black rubber. I know of NO clear tubing I'd want to use unless NASA has something.