Engine/Transmission (1998.5 - 2002) I need a little hand holding here

[Sageair]

I just installed the BD low fuel pressure LED as that is all I can afford right now and I figure it's way better than nothing. But now I know that under full throttle at r. p. m above about 2500 the Led is coming on indicating that fuel pressure is dropping below 5 P. S. I The truck runs exactly like it has for the last 52,000 miles since new. Should i be worried or is it possible that what I am seeing now has been what has always been? Maybe ignorance was bliss.

At anything less than full throttle at higher r. p. m all is well. What does a healthy stock lift pump pull down to?

 

[KBaucom]

If you have 5PSI then you are burning up the VP-44 you need a diffrent fuel pump do something soon

 

[Sageair]

If you have 5PSI then you are burning up the VP-44 you need a diffrent fuel pump do something soon

I appreciate your quick reply. From what I have read the new in tank pumps drop down to almost 0 P. S. I at w. o. t. Since the engine is still under warranty I am in a bit of a quandry?

 

[Joe Mc]

Sageair - with my Comp on 5X5 and Don's 1. 6 injectors I have not seen below 8# @ WOT. I wouldn't let dealer install the intank. So the "quandry" is really this - do you take it to dealer and let them install new in tank set up? I think not. I'm not sure if the dealer would install a new (as it came from the factory) LP at all you could try to insist they replace it with same style and see? They may not even want to replace as it's still working - they have some BS guidline they need to follow. I recall reading some time back that any pressure under 10# regardless of throttle position merits a change. You can go in and try the correct wording they need to hear WTE: "I have experienced a slight loss of power when towing since I first got it - and the mileage has decresed too". For some reason this "was" what they needed to hear back when I was still under warranty some 35k ago. If it were me I'd get a new LP from a Cummins dealer, swap it out yourself and call it a day. Are you reading PSI pre or post filter? Is filter clean / not too old?

 

[Sageair]

I'm reading pressure right where the Shrader valve was on the VP44. Filter is about 4000 miles old.

 

[SKneeland]

ive not heard good reports of the new "in tank" lift pump(probably light up your LED even more than now)

chances are thats what the dealer is going to put in your truck.

key words like joe mc said, complain about "loss of power & mileage" when you go in if this is the route you wish to take, dont point out your fancy new light, they will argue till you're blue in the face that pressure doesnt matter



other options:

1install an old style lift pump (i would relocate to the frame by the tank)

2install aftermarket kit (FASS, RASP, etc. )

3add pusher pump to existing system (carter, will still need to replace your existing pump to prevent restriction)

4invent & build something you're happy with. .

 

[Joe Mc]

So you're reading post filter - LP on the way out - skneeland had some good ideas - I relocated my filter and LP back by the tank some time back. Works fine.



See if you can get the dealer to do a replacement pump for you - and skneeland is absolutley correct do not even meniton your light - if you do you might as well just turn around and walk out. Keep us posted they should do the LP replacement for you. If they say they don't stock them tell them you'll run over to Cummins to pick it up after they fax the PO. Or, if they reimburse the cost you'll go pick it up.

 

[JKinney]

It was my understanding that if; You go in there discussing the possibility of low fuel pressure, your gona get to pay alot of money for a fuel filter and the labor to install it, not to mention the amount of time they have your rig and the down time that you dont have your rig. Those internet specials on pumps $139. 00 seem pretty cheap to me.

 

[GOT-Torque]

I'd just get a replacement pump for around $139 online and get the vulcan big fuel line kit, which also moves the LP to the frame rail. Very easy to install, and you can keep your existing LP as a spare. It would be easier to swap a LP on the frame rail as opposed to the stock location if you ever had to.



I have this very setup and with my comp on 5x5 with DDII injectors I've never seen below 11. 5 psi post filter. 15 psi idle and normally around 13. 4 psi regular driving.

 

[Sageair]

Thanks to all who replied. I'm one of those people that give alot of thought before jumping. It looks like the Vulcan kit and a new pump at the tank is a reasonable and prudent fix, plus I'll have a spare that's easy to install. Once again thanks. Steve

 

[Huff N Puff]

The in tank pump is a good Idea for a stock truck

I just installed the BD low fuel pressure LED as that is all I can afford right now and I figure it's way better than nothing. But now I know that under full throttle at r. p. m above about 2500 the Led is coming on indicating that fuel pressure is dropping below 5 P. S. I The truck runs exactly like it has for the last 52,000 miles since new. Should i be worried or is it possible that what I am seeing now has been what has always been? Maybe ignorance was bliss.

At anything less than full throttle at higher r. p. m all is well. What does a healthy stock lift pump pull down to?

The old design was prone to problems because the in tank unit was very restrictive and was prone to leaking air. No matter how big your lines are or how strong your pump is if you leave the restriction in the tank,that can leak air into your fuel stream, you are wasting your time. Put the in tank pump in, its adequeate for a stock truck,If you are planning on some power mods add a stock lift pump in addition to the in tank pump. Pressure is only one part of the equation,volume is just as important.

 

[SKneeland]

"Put the in tank pump in, its adequeate for a stock truck,If you are planning on some power mods add a stock lift pump in addition to the in tank pump. "



i wouldnt advise this. 1 its been shown that its not adequate for a stock truck. 2 its like putting a bandaid on the problem.



why go to all the trouble of redesigning your fuel system only to end up with a half-assed solution?. do it once and do it right. two pumps mean you now have twice the chances of a system malfunction



stock LP on the frame,big line kit & replace banjos would be my choice considering your circumstances. cheap, available, definately easy to replace (after the move). will provide enough fuel for minor to medium upgrades in the future.

 

[Huff N Puff]

"Put the in tank pump in, its adequeate for a stock truck,If you are planning on some power mods add a stock lift pump in addition to the in tank pump. "



i wouldnt advise this. 1 its been shown that its not adequate for a stock truck. 2 its like putting a bandaid on the problem.



why go to all the trouble of redesigning your fuel system only to end up with a half-assed solution?. do it once and do it right. two pumps mean you now have twice the chances of a system malfunction



stock LP on the frame,big line kit & replace banjos would be my choice considering your circumstances. cheap, available, definately easy to replace (after the move). will provide enough fuel for minor to medium upgrades in the future.

Why would you put a big line kit on your pump,and leave a small line in the tank. Its like putting a set of twins on your truck and leaving the stock air filter box on the end of em.

 

[darkhorse]

Why would you put a big line kit on your pump,and leave a small line in the tank. Its like putting a set of twins on your truck and leaving the stock air filter box on the end of em.

I got all the parts to replumb from the tank to the VP44. 6 & 8 an. Working from the VP back. First line didn't change any pressures. Second line (ie between filter & lift pump) brought my pressure right up to a steady 10 psi that refuses to be drawn down more that to 8 psi. That's plenty to feed my "mildly" fueled motor.

 

[JKinney]

A small line out of the tank?



All I know is that prior to installing a big line kit, I could draw the pressure down to 5 psi. After moving the exsisting pump, cuting the line about 1 foot out of the tank and installing bigger lines I cannot get my pressure to drop below 12 psi even when pulling 10,000 lbs

 

[SKneeland]

"Why would you put a big line kit on your pump,and leave a small line in the tank. Its like putting a set of twins on your truck and leaving the stock air filter box on the end of em"



because my "small line" in the tank still has me at over 15psi at the vp @ wot with my big lines and FASS... .



i should mention i have gutted the filter/mesh out of my in-tank canister.

 

[Huff N Puff]

"Why would you put a big line kit on your pump,and leave a small line in the tank. Its like putting a set of twins on your truck and leaving the stock air filter box on the end of em"



because my "small line" in the tank still has me at over 15psi at the vp @ wot with my big lines and FASS... .



i should mention i have gutted the filter/mesh out of my in-tank canister.

The effective area of the fuel line in the fuel tank module, that the lift pump draws thru is a little more than a 1/4in,there are only two ways to move more fuel to the lift pump, one way, is to open up the line to the tank, or use a pusher pump in the tank to push the fuel thru the restriction with an in tank pump. A pressure guage cannot tell the difference between a solid stream of fuel and a frothy stream.