i got everything i needed including a small inline fuel pump for $53, ran a relay to the new fuel pump wired off of the stock LP and now have over 15psi at idle and 12-13psi driving around!!! that is up from 10 idle and 8psi driving around with stock LP. this is not a permanent fix but one to ensure i have good fuel pressure till i figure out exactly what kind of fuel system i will run.

 

As long as you have positive pressure at the inlet to the IP, your lift pump is supplying more fuel than your IP can use.

 

well at WOT before new pump, i was pulling pressure down to 6.5psi... everywhere i look says that minimum is 5psi for the vp44 to prevent overheating, so it was too close for me. now i dont have to worry about it getting down that close. for $50 i almost doubled my psi. at $1,000-$1,500 for a vp i would just as soon give it every chance possible to live as long as possible.

 

Who cares, if the lp is supplying just enough fuel for the vp, that means its getting zero fuel to cool the pump. The excess fuel pressure makes sure the vp dosnt burn up.

 

X2 it is cheap easy maintanence to help the vp last as long as it can

 

Not true. FP has no effect on cooling the VP once you have positive pressure to the VP.

The VP's cooling fuel is limited by what the VP inlet allows in.

Cranking up the FP won't force the VP to swallow more fuel, and will not cool the VP any better at all.

JH

 

I was showing 6 lbs after the filter (IP side) and getting death codes when the filter was partially plugged. Changed the filter and codes went away so I like to try to keep mine at 7 minimum.

 

Justin, You can drive your truck around with 1psi of FP if you want to but I think I will pass on that.

 

i understand that giving it more pressure will not make it take in any more fuel.. but it does need fuel to send to the motor and to cool itself.....i would rather have more than enough for the pump than not enough or none at all. i feel better knowing i have lots of fuel for it to drink.

 

If your pressure is that low, then you have a weak, or dieing LP, and you need to do something about it before it goes plum-out.

 

Hohn is correct. However, there is an optimal range of fuel pressures, lower end of which is 5 psi and high end is about 15-17 psi (arguable). As long as there is positive FP at the IP inlet, VP44 is getting all it can use for injection, cooling and whatever else. The point is, with <5 psi on the gauge, there may be no pressure at the VP44 inlet on rapid acceleration or heavy load because of the pressure drop across the line between the gauge and VP inlet. This is why it is better to not allow FP to drop below 5 psi.
-P

 

The only reason pressure exists at all at the inlet to the IP is the refusal of the primary vane pump to accept more volume of fuel than its displacement is capable of at a given RPM. Excess pressure does nothing to cool anything. Lift pump failure causes VP44 failure due to it completely blocking fuel flow to the VP44. Many european cars use the VP44 WITH NO LIFT PUMP, instead relying on the interval vane pump of the VP44 to draw fuel from the tank. It would appear as though the need for a lift pump on the Ram is due to how low the fuel tank is in relation to the IP, i.e. the vertical draw is too high. (My theory, nothing official to back it up.)

If you don't believe me, purchase the Bosch CD on the VP44. I did.

I'll let you know how it works out for me. I currently have the factory upgraded in-tank pump. 8 psi at idle, 6 at cruise and 4 wide open. Been that way since the pump was installed. Been running great for thousands of miles. I don't plan on messing with it unless I notice a change in my pressures. Might be a $1200 experiment, who knows, but I'll take one for the team.

 

It does not cool the pump, rather keeps it lubricated. VP44's are only lubricated with fuel. Cooling is not going to happen much since the pump is mounted right to the hot engine block.

 

I want at least 10 psi minimum that's all I want at WOT or whatever. Just give me at least 10 psi. If the injection pump fails it fails but I want to at least give it a fighting chance.

 

X2 call it whatever you want....cool, lubricate, maintain, etc. the vp. as expensive as they are i want to make sure that it has lots of fuel to drink. if it goes bad it will not be from a lack of fuel.