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VP44 problems ?????

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Ok. I see you guys say 20-15 psi on fuel pressure is good. I got some gauges and it reads 10psi at idel and 5-6psi WOT. I thought maby I hooked up the gauge wrong and so I did it again and I am sure its right. Now what do I need to do. Truck never studders and starts good hot or cold. Truck runs good really if I did not have gauges I would not be able to tell the difference. I dont want to run the VP low on fuel since that all that lubs it. What should I do?

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  • Author

Yep that was the first thing I did and then I replaced the FP sending unit.

  • Owner

Fuel pressure normally tells the full story for you... Like mine is 17.5 @ idle and no lower than 15 @ WOT. Now with my old Carter pump typically I saw 14 @ idle and 12 @ WOT. Once if fell to 11 at WOT it was time to change... Being the factory lower limit is 10 PSI... Stock carter lasted about 9 months to 1 year if you lucky... So get a fuel pressure gauge, change your filter, and check for air leaks...

  • Author

Fuel pressure normally tells the full story for you... Like mine is 17.5 @ idle and no lower than 15 @ WOT. Now with my old Carter pump typically I saw 14 @ idle and 12 @ WOT. Once if fell to 11 at WOT it was time to change... Being the factory lower limit is 10 PSI... Stock carter lasted about 9 months to 1 year if you lucky... So get a fuel pressure gauge, change your filter, and check for air leaks...

I have got a fuel pressure gauge and I just replaced the fuel filter to see if that was the case.

You could possibly have a 'slight' restriction in the fuel lineeg 'pinched' somwhere - which restricts your flow - especially with that drop at WOT.Although if you have OEM its probably just thatI think a volume test would PROVE that - you crank the lift pump - and bypass the fule into a measuring cup :) I am sure I did that from info from this site - if you search under vp44 michael has it somewhere - if nothing else its kinda interesting Might also save you with same issue if you install a FASS/AIRDOG - oh - *doh* except you replace the OEM lines ..... :lmao:yeah - I think the airdog is my BEST mod - it was like $500 and another $200 for the coupled guages (DON"T FORGET THE GUAGES) -> I know I am always getting a good supply of fuel - 14 PSI at WOT and 17-18 at idle/max.

  • Author

Sorry... Long day and did go back to read the initial post... So what is you pressure now?

It reads 10psi at idel and 5-6psi WOT. I replace the fuel filter and replaced the fuel pressure sender and still the same.

It reads 10psi at idel and 5-6psi WOT. I replace the fuel filter and replaced the fuel pressure sender and still the same.

You are not getting enough pressure and not enough volume because of the low pressure. The pressure needs to be about 17 at idle and not below about 13 at wot. unfortunate thing is your VP44 may have already been damaged by the low pressure. Its at least lift pump time.
  • Author

You are not getting enough pressure and not enough volume because of the low pressure. The pressure needs to be about 17 at idle and not below about 13 at wot. unfortunate thing is your VP44 may have already been damaged by the low pressure. Its at least lift pump time.

I sure hope the VP44 is not damaged. I am going to replace the lift pump with a Raptor 100. Everything that is going on leads to a lift pump going bad right. Any other lift pumps that are recommended as a real good pump that will last. I really like the raptor because its adjustable but then WHAT DO I KNOW>:shrug:

I sure hope the VP44 is not damaged. I am going to replace the lift pump with a Raptor 100. Everything that is going on leads to a lift pump going bad right. Any other lift pumps that are recommended as a real good pump that will last. I really like the raptor because its adjustable but then WHAT DO I KNOW>:shrug:

The raptor is a good pump. So are FASS (not the ddrp), and AirDog, Both of them have air/water separators and filters but they are more money. It's up to you and what you want to spend.:spend::broke:
  • Author

The raptor is a good pump. So are FASS (not the ddrp), and AirDog, Both of them have air/water separators and filters but they are more money.

It's up to you and what you want to spend.:spend::broke:

Well I guess I will have to order a lift pump and cross my finders the VP44 is not damaged.

---------- Post added 04-25-2010 at 08:11 AM ---------- Previous post was 04-24-2010 at 09:20 PM ----------

How do I know whether or not my truck has the in tank pump also. I was looking at raptor lift pumps and they had one that came with a suction tube or draw straw with the modles that had a pump in the tank. I belive I located my lift pump on the side of the block. Is this the only one in the line or could there be one in the tank? :ahhh:

Well I guess I will have to order a lift pump and cross my finders the VP44 is not damaged.

---------- Post added 04-25-2010 at 08:11 AM ---------- Previous post was 04-24-2010 at 09:20 PM ----------

How do I know whether or not my truck has the in tank pump also. I was looking at raptor lift pumps and they had one that came with a suction tube or draw straw with the modles that had a pump in the tank. I belive I located my lift pump on the side of the block. Is this the only one in the line or could there be one in the tank? :ahhh:

Locate the VP44 follow the fuel line back to the fuel filter canister, trace the fuel line that feeds the filter back and if it is connected to the pump on the block, that should be the functioning lift pump. if the line bypasses that pump then your pump is further back and probably in the tank which means you will need the draw straw.

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    • Author

    When I install a new lift pump do I remove all the old fuel lines and the old lift pump or can I just leave it on there?:shrug:

    When I install a new lift pump do I remove all the old fuel lines and the old lift pump or can I just leave it on there?:shrug:

    I don't know of any requirement to remove the old lines, but if you are looking to reduce the truck weight have at it.:thumb1:
    • Author

    I don't know of any requirement to remove the old lines, but if you are looking to reduce the truck weight have at it.:thumb1:

    I supposs all that wouldn't make up to much weight anyways so If I can i guess I will just leave it on there. :whistle:

    I supposs all that wouldn't make up to much weight anyways so If I can i guess I will just leave it on there. :whistle:

    Leave it on there - that way if your FASS/AIRDOG/RAPTOR fails for some dumb luck - and you ain't near "help" you can at least put the other one back on to milk the truck home or somewhere. Or if you get a new truck - take the raptor with you - gonna be hard to sell the old one with no fuel pump or lines :thumbup2::)
    • Author

    Leave it on there - that way if your FASS/AIRDOG/RAPTOR fails for some dumb luck - and you ain't near "help" you can at least put the other one back on to milk the truck home or somewhere. Or if you get a new truck - take the raptor with you - gonna be hard to sell the old one with no fuel pump or lines :thumbup2::)

    Verry good point never thought of that.
    • Owner

    Leave it on there - that way if your FASS/AIRDOG/RAPTOR fails for some dumb luck - and you ain't near "help" you can at least put the other one back on to milk the truck home or somewhere. Or if you get a new truck - take the raptor with you - gonna be hard to sell the old one with no fuel pump or lines :thumbup2::)

    Just to make sure you cover up the the fuel line ends so no debris or water gets into the old system... Other than that it becomes useless if its plugged with mud or pumping debris...:stuned:
    • Like 1

    Just to make sure you cover up the the fuel line ends so no debris or water gets into the old system... Other than that it becomes useless if its plugged with mud or pumping debris...:stuned:

    I may have to check that I did that ..... hahaha - good point :thumb1:
    • Author

    I got to thinking today. Is it posible that the overflow valve on the VP is stuck open and letting the pressure drop. I not real familuar with injection pumps so forgive me if this sound stupid :cookoo:. Maby thats why my fuel pressure is low. I just thought of that today for some reason. Is it posible?

    I got to thinking today. Is it posible that the overflow valve on the VP is stuck open and letting the pressure drop. I not real familuar with injection pumps so forgive me if this sound stupid :cookoo:. Maby thats why my fuel pressure is low. I just thought of that today for some reason. Is it posible?

    Don't think so from what I've learned about the vp44 on this forum. Read this thread through to the end and you will see what I mean: http://forum.mopar1973man.com/showthread.php/1656-VP44-Write-Up-Minimum-pressure-suggested...
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    Welcome To Mopar1973Man.Com LLC

    We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.