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flman

Newb with low power all ranges

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Great site, glad I found it. My name is Bob Donnelly, I have a Freightliner FL50 with a Cummins ISB and, Fuller Eaton 6 speed. At 117K I replaced my VP44 because the truck was not running the same. Chip at Blue chip diesel, determined the computer on the VP44 was bad, so I replaced it , and the power was back. At only 120K I am having the same issues. Chip said to take it in for DTC scan. I did, it has no codes, the owner of the shop, said to test the wastegate, and to replace the leaking exhaust manifold gaskets. The wastegate leaked, so it has been replaced, and the manifold has new gaskets and bolts. I installed a fuel pressure gauge in dash at the time of the VP44 replacement, because pumps have failed before, and I usually would not even know this until a filter change or a flat spot on acceleration. I am getting about 10 PSI at idle and 7-8 psi at WOT. Both of these pressures will drop when it is colder out and slowly rise as the fuel thins out. If any one has any ideas, other then I got a bum VP44 let me know.Once again, great site, and thank you Mopar1973Man for all of your effort.

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Fuel pressure is too low to start with...:eek: http://mopar.mopar1973man.com/cummins/2ndgen24v/fuel-pressure/fuel-pressure.htm so its really possible your slowly killing that VP44 with lack of fuel pressure. Being the only thing that cools and lubes the VP44 pump is the extra fuel pressure. It like running a engine with 8 PSI of oil pressure there just not enough to keep the metal to metal surfaces lubed and cooled with a lubricant like diesel fuel.

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You are the first one to consider that pressure to be too low. My ears are open and I am listening to you. Will that low pressure cause the problems I describe, or will it just be harmful to my VP44?Blue Chip did not have any problem with that pressure, and the diesel truck repair shop that scanned for codes said it was OK? I am planning on doing the fuel volume test, and air bubbles on the pump, and throwing in a new filter for good measure. I do keep a spare OEM pump in my truck for emergencies, but I would really like to go with a Fass.

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Welcome to the site. Like Mike says, Cummins says the minimum fuel pressure is 10 psi. It is like your trying to fill a bucket of water with a cup yet it is leaking out a cup and a half. After having run 18 wheelers my self, think of it this way:do yyou need more skinny pedal when your on flat ground or when your stopped on a hill and trying to move your rig. Get the Fass that you want with 1/2" lines and make your VP happy.

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You are the first one to consider that pressure to be too low. My ears are open and I am listening to you. Will that low pressure cause the problems I describe, or will it just be harmful to my VP44? Blue Chip did not have any problem with that pressure, and the diesel truck repair shop that scanned for codes said it was OK? I am planning on doing the fuel volume test, and air bubbles on the pump, and throwing in a new filter for good measure. I do keep a spare OEM pump in my truck for emergencies, but I would really like to go with a Fass.

The only thing about Chip that i don't tend to agree with is... Yes a VP44 will run on ZERO PSI of pressure... But no one has ever dyno a vehicle for long haul distances with 5 PSI and proved without a doubt that 5 PSI is enough. Now I know Chip has put pump on his pump stand and run the with 5 PSI and done well. But once again there is no long term testing of this. There is not a single person that can stand up in the crowd saying he's put on more than a 100K miles with 5 PSi of fuel pressure... :shocked: Yes running a race truck down the 1/4 mile track with 5 PSI will survive the trip. But we don't race for a living we drive long haul like CajFlynn with over 760K+ miles on his truck! Ok another thing the overflow valve opens at 14 PSI so at pressure below this there is no extra cooling and lubrication happening for the pump. This why most set there pump to push about 15-17 PSI so that valve is slightly open and a few extra GPH is flowing through the pump adding to the cooling/lubing purpose. Low pressure means low volume of feed. So the lift pump and supply tubing is restrictive and the VP44 is starving for that extra fuel. Bosch itsself even states "70% of the supply is suppose to be returned to the tank only 30% is to be burned" Now here that from Bosch (the pump manufacture) that raises a eyebrow. Now to give you a feel for consumption... Stock fuel pump supplies roughly 25 GPH with stock lines. My truck with just a Edge Comp on 5x5 will consume 27 GPH at WOT... :shocked: The stock lift pump cant keep up with stock pumping... That why I went for a AD 150 with 1/2 inch lines... :thumbsup:

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OK, guys Chip sells the Fass, but do you know of a better cheaper place to buy the pump? And I am pretty sure my FL already has the 1/2" lines from the factory, since I was just out there, I did the volume test and got just shy of 1 - 1/2 quarts with the key on no start. I put in a new fuel filter, and even swapped out the transfer pump. With fuel temperature in the teens, I am still only getting about 8 PSI with a brand new OEM transfer pump. I still have a suspicion that the VP44 is already failed due to a defective computer? I agree it makes good sense that excess fuel that is by passing the ball check banjo is a good idea for IP cooling and lubrication is a good idea.

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The AirDog pumps seem to be getting better reviews for both performance and customer service. Actually they are father /son businesses. Father owns FASS Son owns Airdog, family feud caused son to form airdog company to show up pa. Little known facts.:wink:

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Hey,My Air Dog II seems to work really well!!!:thumbsup:I would contact Diesel Auto Power (Jkidd) and let him give you a good deal!!!:thumbsup:Later,Winslow

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I have the 150 version of that. It is ok but when it gets down to around 10 below it doesn't pressure up right away. It runs but it takes a bit to build pressure but only at startup after a minute or so it comes to life.

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Glad you got one coming. Anything is better than stock. Once you get that all in you will feel a lot better seeing the pressure go up! Good luck!

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I have the 150 version of that. It is ok but when it gets down to around 10 below it doesn't pressure up right away. It runs but it takes a bit to build pressure but only at startup after a minute or so it comes to life.

I am not worried about 10 below, we hardly ever see it, and I park the truck in my shop. Unheated but better then out doors.

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Got the pump today, that thing is a lot more of a pump then the factory one will ever be. What is it, a gear pump, sort of like you would have on a home oil burner? Well, maybe if I get some time tomorrow I will find a suitable place to mount it, get it mounted, and move on to the piping and wiring if I get time. I think the new wastegate actuator did help with some of the power loss, I had it on the interstate today, on a long grade, where it was previously dropping speed in cruise control, it actually held its own, with no speed drop. It still is missing some power though. Maybe once I get good fueling, the computer will tell the pump to start feeding the injectors more?

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Couple of questions, the pump is not identified by inlet and outlet, I assume T is tank, and E is engine? Also, will the stock electrical connector supply enough amps to run this pump, or do I need a heaver power source, such as use the stock wiring to run a relay? On the parts list it says, "Electrical harness with relay" There is no relay, only a fuse?

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Well, got the Fass pump system all installed and 'Big Blue" is running alot better now, thanks to to finding this site. It has much better throttle response, and it has got its distinct "Cummins Cackle" back. I noticed when I let the clutch out she snorts and jolts like a bull, just like she used to. When I first started it I got a CEL and a code ECU 128, I thought maybe it did not like fuel being fed with the engine not running, during the GP warm up, so I wired a relay into the stock fuel pump wiring to make the ECU think every thing was normal. I left the old pump on the engine, and the old fuel line to the tank with a plug in it, but not connected. If I ever had a problem with the Fass, I still could connect the old system in an hour if need be. Thanks for all the help, look for forum donation to help the site.

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Got the pump today, that thing is a lot more of a pump then the factory one will ever be. What is it, a gear pump, sort of like you would have on a home oil burner? Well, maybe if I get some time tomorrow I will find a suitable place to mount it, get it mounted, and move on to the piping and wiring if I get time. I think the new wastegate actuator did help with some of the power loss, I had it on the interstate today, on a long grade, where it was previously dropping speed in cruise control, it actually held its own, with no speed drop. It still is missing some power though. Maybe once I get good fueling, the computer will tell the pump to start feeding the injectors more?

Well as for the fuel issue the VP44 can draw its own fuel but hates like hell to do it. So since there is little to no fuel pressure there isn't anything to advance the timing cam plate so it stays in full retard mode... Hence the lack of power...

Couple of questions, the pump is not identified by inlet and outlet, I assume T is tank, and E is engine? Also, will the stock electrical connector supply enough amps to run this pump, or do I need a heaver power source, such as use the stock wiring to run a relay? On the parts list it says, "Electrical harness with relay" There is no relay, only a fuse?

I would hook up a realy just for safety sake. The ECM is what powers the lift pump directly. So if the current load gets to much then the ECM might fry...

Well, got the Fass pump system all installed and 'Big Blue" is running alot better now, thanks to to finding this site. It has much better throttle response, and it has got its distinct "Cummins Cackle" back. I noticed when I let the clutch out she snorts and jolts like a bull, just like she used to. When I first started it I got a CEL and a code ECU 128, I thought maybe it did not like fuel being fed with the engine not running, during the GP warm up, so I wired a relay into the stock fuel pump wiring to make the ECU think every thing was normal. I left the old pump on the engine, and the old fuel line to the tank with a plug in it, but not connected. If I ever had a problem with the Fass, I still could connect the old system in an hour if need be. Thanks for all the help, look for forum donation to help the site.

Well you did the right thing then... But I doubt you'll have a problem with a FASS pump... But I would take the time next and get a 0-30 PSI fuel pressure gauge and hook it up if you don't already have one...

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M1973M, I would not dare hooking the Fass to the factory connector, that wiring looked way to small, compared to the Fass wiring with a 30A fuse in it. I used a 30A relay to make and break the pump circuit so the ECM thinks all is well, and for safety as well. I already had the gauge installed, and the pressure is at 14 PSI with the new pump, thanks for the help. I am going to take it for a ride on the Interstate Monday, hilly area in the Catskill Mountains.

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Got the VP44 swapped out today, so far so good, big blue feels like her old self again :)1/2' supply lines are next on the agenda, I have to make this pump last.

Edited by flman

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