bentwings

Since it started getting down into the teens (F) my lift pump has been showing lower pressure. When it is warm out say 60+ I normally run about 12 crusing and 9 WOT.
Lately when it is very cold in the single digits it runs around 6-7 psi. After about 1/2 hour to 45 min on the highway it gradually creeps up to about 11psi. Drops to 8 WOT the couple times I checked it. Once I have about an hour on the highway it settles to about 12 the same as in the summer.

Last year it seemed to be always above 10 psi regardless of temp even to well below 0.

The other thing is that the gage has started chattering quite a bit and is getting worse. It more or less goes away on the highway but in town it chatters.

It looks to me like it is slowly going away. We do have B-2 at the pumps now so that may have a little to do with it as it is supposed to be a bit "thicker". I use a big dose of PS at each fill and I usually keep the tank above 1/2.

I was hoping I could get by untill spring and update to at least relocation and maybe an additional pusher. Vulcan kit.

It's going to be a freezing cold deal to change it as I live in an apt and everone's garage is full.

Lift pump has right at 40,000 on it and I just changed filter about 4000mi. ago. Fleetgard. I had 13 psi on the filter side after the change.

I won't be doing any heavy towing just going back and forth to work. Think I can make it 4-5 months???

Clunk

My pressure is down a pound or 2...did it last winter too. Most likely will do it next year too. I think cold thick fuel is harder to push through the filter. Have you installed a needle valve on your gauge line? I have one on mine...pic in my gallery.

Mopar1973man

In the morning first part of the start I've noticed that the pressure is down considerable with the grid heater stealing power. But returns to normal after the grid heater shuts down.

Yeah.. I have notice running PSI's are bit lower about 1-2 PSI but not to bad..

MARKY MARK

I've noticed the same thing. As the day warms up, my pressure goes up.

bentwings

I don't have a restrictor but the gage is a high quality industrial gage.

The psi gets better after about an hour of running but it is still way down from a week ago. It was 7 below 0 F today in the morning and supposed to be colder tonight. bbbuuurr

When the grid heater is on the psi goes down a couple. Always has.

I think the check valve inthe pump is getting beat out. that's what happened to the last one.

I called Vulcan today and I'm going to order his kit Friday and I found a brand new lift pump on e-bay for about $115 pluss shipping. that's about the best I can do.

I'm going to be doing this the hard way out side in below 0 weather. I just filled the tank too so I'll be getting a cold diesel bath. Maybe if I drive around for and hour or so the tank will heat up a little. The hottest I ever saw it was about 15 deg over ambiant however. The lady that run this apartment hates my truck and she comes out if so much as open the hood to check the oil. I'll probably have to do this at night with a flash lite.
Vulcan says it is an easy install and I don't even have to take the old pump off. sure hope so.
Anybody got a list of tools I'll need??

bentwings

Mike D

I noticed the same thing in colder weather especially on cold morning starts. Even after the grid heaters do their thing, pressure is down. I personally think it's the cold diesel fuel causing the pressure drop. As you run the truck, warm diesel fuel is returned to the tank and warms the rest of the fuel in the tank. After running the truck for a while I see the fuel pressure come back up to normal. I'm running the Holly Blue pump now.

Ben

I used to experience the same thing. What helped was mixing about 50/50 of #1 and #2 and still use additive for lube properties. Now, I am sure you can get away with just using an anti gel and regular #2 but for me using blends of #1 and #2 when it goes below zero really helped the FP. I am talking about -20 to -40 on the thermometer.

This summer I put on a Fass II and Vulcan line from filter to VP and I have notice NO change in FP due to the cold weather like last year. It was -10 yesterday morning. The larger fuel lines I feel help out quite a bit.

Good luck!

SuperDave4x4

Are you running the Vulcan relocation kit and just using the Fass II pump as a stand alone pump, or are you using the stock LP also. Reason being is when my Blue pump burns up I'm going to put the 150 GPH fass II pump in its place. How does that sound?

Also I have noticed that my fuel pressure is little lower than it has been due to the colder weather and I'm having a hard time getting it to crank.

farmer dave

I also have noticed a slight drop in fuel pressure when cold. It only last a short while though because the FASS moves so much fuel.

waam

Waam here. Had my fuel pressure checked yesterday at the Dodge dealership. Mechanic said mine was 10 to 11 psi. and that was good. Also had new fuel filter installed. My question is what is the high and the low range of the fuel pressure suppose to be, before we have to worry about it. Thanks. Bought diesel fuel for $2.44 a gal. yesterday at the local party store. Waam Holland, Mich.

ds1rider

I get lower pressure when it's hot, and higher pressure when its cold.

Geico266

After re-reading your 1st post I can tell you the chattering a sign of the LP getting weak. There is a check valve in the LP that gives out. Seems like a bouncing fuel pressure gauge needle is a sign of that. I replaced mine when it started and sure enough that was it. Keep an eye on the pressure. Replace it when it gets too low.

bentwings

Geico,
I believe you are right , my first LP failed by haveing the check valve wallow out about a 1/4 inch hole right thru the wall of the pump and into the vanes.

I may have a plugged fuel filter too but I just changed it about 4000 miles ago. I just checked and I still have the extra Schrader valve on the pump housing so when my landlord hits the sack tonight I'm going out and switch the gage lines. haha It wil only be about -10 by then dang why does this happen ont he coldest night of the year???

Geico266

Some guy named Murphy made a law.

Ben

Superdave,

I have the Fass II 95 gph unit. No more lp. The Fass only provides fuel line and fittings to the filter. I called Eric at Vulcan and he was able to hook me up with fittings and hose to the vp, inclding a midline fitting for the fp gauge.

The vulcan stuff is SWEET!! The fuel line looks like a garden hose sitting there. Eric is way beyond top-notch to deal with!!

How old are your batteries? That may contribute to your cranking problems. My truck always pops right off when plugged in, but even at 20 degrees or so not plugged in, there is a huge difference. The cranking is labored. Since my truck isn't garaged all year long, I only give batteries a 2 year "useful" life span. Meaning, if it's 10 degrees out, not plugged in, truck still cranks real well. Cold weather is brutal on batteries.