Archived transfer pump blues

[RBassetti]

I decided to change my transfer pump and move it to the frame on my 2001. I put a BD Diesel bypass kit on that was advertised to give 12 to 14 PSI. Well after three pumps from BD Diesel, I can only get 9 PSI. BD Diesel can't give me a good answer to why the pressure is lower than advertised. They get the pumps from Carter and Carter won't contact them about it. My OEM pump on the engine gave me 10 PSI. The new pump seems to have more volume because the pressure doesn't drop much under load. Just 1 pound. I have trouble shot my truck and nothing is wrong. I don't know what to do at this point, I don't think BD diesel does either. Does anyone have a suggestion as to what to do.

 

[EBung]

I have a Holley blue and am happy 14psi. It does drop when on kill to about 6psi though.

 

[rweis]

Generally, the thing that seems to work is gross overkill of volume, and some sort of bypass right at the input to the VP44 to shunt the excess back to the tank.



The RASP, Walbro, FASS, AirDog, second pusher pumps, etc fall into this category. They can supply about 2x - ?x the volume needed, then a way to set the psi and shunt the excess back to the tank.



This system seems to work fairly well. Most of the bypasses are no longer in the pump itself, but rather by using T's to bypass excess back to the tank through a generally spring loaded (adjustable) bypass valve located on the long leg of the T.



The amount of fuel actually getting into the VP44 is a minor fraction of the fuel available. Depending on the fuel filter setup, you wind up recirculating fuel through the fuel filter system many times an hour and probably wind up with cleaner fuel.



I think the OEM carter supplied just barely enough volume at just barely enough psi to really get the job done at the VP44. Any minor degradation and the VP44 took the hit. The newer non OEM systems are gross overkills on volume, but seem to finally "fix" the lp problem.



WIth a good lp the psi problem is generally a line size problem. I would think you have a line restriction somewhere. You can not get your volume all the way to the VP44.



Bob Weis

 

[RCole]

I also installed a BD pump that is supposed to put out about 14psi. It barely puts out 8 psi . When i step on it it drops to 5 or a little less. My old OEM pump put out a good 11 psi and didnt drop that much when on gas ( diesel). My problem with this is that they advertise it to put out 12 to 14psi. If the pumps wont put it out then dont say that it will. Ray Cole. ( a bit peeved)

 

[Seafood10]

I just installed a Glacier and have 20 psi, all day long. Went through 2 of the Carters and gave them up. The Glacier kit is expensive, but not as expensive as a VP44.

 

[LowFly]

Generally, the thing that seems to work is gross overkill of volume, and some sort of bypass right at the input to the VP44 to shunt the excess back to the tank.



The RASP, Walbro, FASS, AirDog, second pusher pumps, etc fall into this category. They can supply about 2x - ?x the volume needed, then a way to set the psi and shunt the excess back to the tank.



This system seems to work fairly well. Most of the bypasses are no longer in the pump itself, but rather by using T's to bypass excess back to the tank through a generally spring loaded (adjustable) bypass valve located on the long leg of the T.



The amount of fuel actually getting into the VP44 is a minor fraction of the fuel available. Depending on the fuel filter setup, you wind up recirculating fuel through the fuel filter system many times an hour and probably wind up with cleaner fuel.



I think the OEM carter supplied just barely enough volume at just barely enough psi to really get the job done at the VP44. Any minor degradation and the VP44 took the hit. The newer non OEM systems are gross overkills on volume, but seem to finally "fix" the lp problem.



WIth a good lp the psi problem is generally a line size problem. I would think you have a line restriction somewhere. You can not get your volume all the way to the VP44.



Bob Weis

Bob,



You hit the nail on the head. I get the question all the time about "Why don't we make a pump closer to total engine demand GPH?". And i point out that is what the Carter Lift pump was designed to do. Its Tap Dancing on a razor blade if you ask me. Not a lot of give room for restrictions (Filters and such), improper installs, and fueling mods. Why do you think ½” line kits are so popular with Carter Pumps? Takes away restriction and the pump has an easier time to keep up with demand. 1/2 line are not needed on the stronger pump mentioned above.



On the FASS, we move full pump volume through both filters and what the engine doesn't use, we send back to the tank via a return. Take's the pump "Waste" fuel and polishes it if you will.



Another point that was not brought up was the Gauge. MAN, everyone wants to think their gauge is showing them gospel and to tell them they might have an issue with the gauge is blaspheme!! HAHA:-laf:-laf……. BUT troubleshooting our pumps, this is the first question out of my mouth if we see a pressure issue…and I would say that 50% are solved right there. Electric gauge beaten by the VP-44. Isolators that are leaking or sticking. Stuff like that…. .



BUT you made some good points Bob... ...

 

[Joe Mc]

Get an aftermarket "proven system" like one of those mentioned in previous post replys. One of the great things about TDR is the knowledge base available - before you buy the product you think will answer your problem or whatever, ask about it here - then take into account others' comments and make up your mind. Or, ask what others have done to aide problem or what you are trying to do then use replys to help you determine. Homework, homework, f-n homework helps.



By the way I went through 3 Carter stock LPs before I mounted one on the frame rail, since it didn't last any longer than the other 3 in that location - I decided after throwing away my $$$ on junk (3 pumps - Duh yep I'm pretty dumb at times) I'd go for one of the aftermarket "systems". As previously mentioned by someone that also has same system, 20# "all the time" and yes even with a mechanical gauge after the filter. it's rare to see the gauge below 18# even @ WOT w/comp @ 5/5. So choose the right system for your needs (don't forget to leave room to grow into it - even though you wont be adding power enhancement in the future - yeah right - lol) honker down and get it and install then - "don't worry, be happy".