Engine/Transmission (1998.5 - 2002) Fuel pressure question

[DanielHaney]

I have a well used 2001 Ram 2500 bone stock (210,000 miles) I just replaced the lift pump with an OEM (carter) and the VP44 in response to a P0216 code. The thing runs great now. Since this is my second VP44 I thought I might try one of those idiot light pressure switches on the VP44 suction. The thing is made where the light comes on when the fuel pressure drops below 5psi. I noticed right off the bat that when I accelerate hard the red light comes on... going off once I level off. I'm assuming this means my fuel pressure is less that 5 psi while accelerating. Doesn't sound good to me.



Any comments or suggestions where to go next

 

[DCreed]

get a GOOD LP and mount it near the tank.

 

[JLandry]

Daniel,

Yes... assuming the sender on the low fuel pressure idiot light is accurate (that's questionable), you're subjecting the VP44 to 5psi (or below) and this is indeed bad for the VP44 and can damage it.

But very first thing you should do is verify you actually have a problem. Check the fuel pressure at the VP44 inlet using a pressure test gauge. You can buy a fuel pressure test set at Harbor Freight Tools on sale for less than $20.

In the mean time, if you haven't changed your fuel filter recently, that alone could cause low fuel pressure. Try swapping the fuel filter out and see if that solves the problem.

Also, with that many miles on the truck, the inlet screen on the fuel pickup module in the tank could be obstructed with crud. You'd have to drop the tank to check and clean it.

Of course it could just be the stock lift pump you installed... they're notorious for low pressure. A much better alternative is the Airtex gearotor type pump which will bolt directly in the stock location. I have one on my truck in the stock location and it supplies 18 psi at idle and never drops below about 8psi under hard acceleration. At cruise the pressure is typically around 15psi.

Good luck,

John L.

 

[blacksheepdiesel]

An idiot light is a good thing for warning you instantly of low fuel pressure. However, you will still need a fuel pressure gauge tapped in between the filter and the VP. This gauge is a must on VP trucks. Do your wallet a favor and get one now. It will tell you when to change the filter and when the lift pump is weak or dead and will also keep you from damaging the VP by not feeding it enough fuel.

Godspeed,
Trent

 

[DanielHaney]

JLandry,

Thanks for the insight. Makes a lot of sense to me. I was curious about the quality of the stock lift pump.



I dropped the tank and cleaned the screen as part of this project. Sounds like I need to get a gauge and a possibly a different lift pump. I'm going to check the fuel line from the vp44 back to the water separator today for possible obstructions (that's the only part I haven't already blown clear.



Daniel

 

[RJWEST]

I'm Old, Fuel pressure gage, Warning Light AND Buzzer...

 

[cArNiVaLwOrKeR]

***RAPTOR***



JoeLee

 

[Chief USA]

I recently purchased a 100% stock 2001. 5 Ram 2500 for the wife and found the fuel pressure at 2 psi when I got it home. (I forgot to bring my manual fuel pressure test gauge) I replaced the filter but the stock Carter pump would only make 9 psi max. I replace it with an Aertex 7153 pump which brought the pressure up to about 18 at idle but could be pulled down to about 8 psi on a hard 5th gear pull. It worked good but not good enough.



I recently installed a 1/2 inch Vulcan Big Line/Pump relocation kit with an Aertex 7153 pump I had Eric at Vulcan modify for me to accept a 1/2 inch AN fitting. The fuel pressure on this setup holds a fairly steady 19 to 20 psi and can be pulled down to around 15 psi on a hard 5th gear pull which is VERY satisfactory for me.



Eric recently introduced a new kit a the week before last which uses an Aertex 8845 pump and relocates it to the frame and converts to 3/8 lines. I am sure Eric can whip you up a nice kit using 1/2 lines. That would give you 1/2 inch fuel lines from the output side of the pump all the way up to the fuel injection pump if you use the 1/2 inch Big Line kit.



For a stock truck, I think the Aertex pump is a good choice but the best way to go in my opinion is the Air Dog or FASS. These pumps can handle any mods you decide to add on later.