Engine/Transmission (1998.5 - 2002) Question about the new in-tank lift pump

[Texas Diesel]

What kind of pressures are you seeing with the new in tank lift pumps?

 

[JeffWhite]

soon

I can't tell yet, I'm supposed to be having this done soon, maybe next

week. Do a search on in tank retrofit though - I did, and several guys

said they are only getting 7-8 idle and 3 or so at WOT. I don't like the

sounds of that, but don't know what else to do. Mine is still under

warranty, and I'm not gonna go buying FASS or something now.

The dealer tried to order the old style pump, and it kicked the order back.

BTW, my original lift pump is fine, 11-16 psi. What is wrong is a dying

VP - it has never seen low fp, but the electronics are crapping out.

Dealer says they automatically replace BOTH when they do it, sounds

like good logic to me, but I am not looking forward to lower pressure with

the in-tank... Maybe the cure is gonna be worse than the disease.

 

[wtfd6]

What kind of pressures are you seeing with the new in tank lift pumps?

it will be interesting to see.



mark

 

[JKinney]

Mine is in the DC shop right now under warranty for a dead IP I was told friday the IP is in and the might install it monday or tuesday. I have been told nothing about a fuel pump. I put a new lift pump in three weeks ago, thats my third. I have 46,000 miles.

 

[CSnyder]

I have a good friend who did the very first in tank pump at our local dealership and he also has seen very low pressures with his "new design" pump. I feel it's Chryslers way of saying "you guys have whined so long about our 400 dollar pumps that now we will make it more expensive to replace them so the part cost isn't such a big deal anymore". I will have Carters from tank to VP in series before I will buy another LP from the *******!

 

[todt061458]

Low pressure? I thought I read a thread that pressure was not so important anymore the word NOW is FLOW how much FLOW is the pump pumping. did I read that post wrong? I thought flow was more important than pressure for the VP44 some guys even said high pressure even helped to lower the flow(amount) of fuel to the VP44 pump as fuel is what cools the pump and lubes it I would think quanity of fuel is more important than pressure of fuel to the VP44 as the VP pump will pressurize the fuel to the injectors anyway? So all you experts is it flow or pressure?

Just wanting to understand in Illinois Tod P. S all I want to do is rebuild my fuel system the right way a high pressure system is different than a high flow system.

 

[TMills]

It is a combination of flow and pressure. If you have bigger lines then you will have lower pressure. If you have smaller lines then you will have higher pressure. FWIW, the higher the pressure the hotter the fuel. VP's do not like hot fuel. I think the main point is to make sure that you always have positive fuel pressure to the VP. A high flow system will be better than a high pressure system.

 

[CSnyder]

I have a good friend who did the very first in tank pump at our local dealership and he also has seen very low pressures with his "new design" pump.





I should have been more clear Tod... . with his engine mounted LP he was getting 14 lbs of pressure at idle and with the new in tank model he is only getting 8 lbs at idle and can pull it to zero at WOT with a stock truck. I personally hate seeing 0 lbs even at WOT!

 

[todt061458]

I understand now. Bigger fuel lines=more fuel flow and cooler fuel making the VP44 very happy> I think that's correct. :-laf And the in tank soution by dodge is still not quite right I think dodge needs new engineers. so out with the banjo bolts and in with bigger hoses and -6 or-8 fittings. thanks for the hep my confused mind in now clear.



Tod

 

[fox]

I would think the internal restrictions in the VP-44 would regulate the pressure.

The size of the lines to it will only help keep the pressure at your trucks max, when accelerating. This should keep the temp more consistant.

I am interested in a cooler in line to lower the temps of the fuel before the filter. This of course is a problem in cold weather.

I just changed my original LP. It had dropped to 12 psi, the new one is at 15. These are at idle measurements. I have bigger lines between the LP and IP, and could not drop the pressure below 8.

I think I can feel better throttle response, I want 20 psi.

 

[todt061458]

What we do in commercial trucks(semi's) is they put in a bypass valve turn the valve and the cooler is bypassed for the winter so no over cooling for the winter. we use it for fuel cooling and to bypass the coolant cooler it helps the truck warm up faster in the winter. on the fuel side it stops the return of hot fuel to the tanks and diverts it to a radiator style cooler for the summer. Tod

 

[rweis]

I am puting in a fuel cooler from the VP to the tank and dumping the return into the filler neck and a temp gauge just before the ff so I can see what the VP is getting. Almost all parts have arrived. Probably this tues and wed for plumbing and install. Gauges are on 3 week backorder.



My objective is 80* - 100* input fuel temp to the VP.



I have all AN-6 lines and a RASP driving the whole thing.



Bob Weis

 

[Texas Diesel]

Has anyone actually measured the temp of the fuel feed to the VP-44?