jj3500

Just trying to get my facts straight. truck i have runs awesome. noticed recently that the fp is slightly lower than what i have had. cruising at highway speeds(70ish) was 14, 15 is now hovering in th 12,13 area. just cruising flat terrain no load.

i got on the pedal just to see how it would read...before 9 was the lowest, now i see 7ish area.

truck still runs plenty strong. what is slowly going out if anything? lift pump? not the injection pump?

i've got a carter pusher pump in there now.


thanks for the help

crobtex

When was the last fuel filter change?

John Faughn

Hopfully someone will chim in , but I thought I read [ not sure if its that one ]but even some of the aftermarket systems are having problums, good thing you got a gauge , catch before that pricy one gets it .

99 cummins

My Carter has started to do the same thing. Noticed that for a couple of weeks and now it has gotten to where it sometimes doesn't read any fuel pressure until the trucks been runnin for a few minutes. I'm thinking a bad ground with all the salt and ice on the roads but I haven't crawled under there to check it yet. I'm not complaining to much about the pump I got over 100,000 on it and this is the first real problem.

Geico266

Some times colder fuel runs slower through everything including the filter. IMO just monitor the situation and be prepared for a swap out if it gets any lower.

jj3500

Filter was done about 7K ago.

Geico266

It's cheap insurance to change it and see if your pressures change. If they do then you know your filter was dirty and your LP is okay. If the pressures stay the same (lower) just monitor the PSI. 7PSI is now the minimum WOT from what I read now.

What I just did in the same situation is change out the LP and keep the "weak" one as a spare, but that's just me.

A more permenant fix is to install a FASS II fuel pump. They seem to be a better pump. http://www.dieselpp.com/

bentwings

My LP has been up and down all winter. I watch it like a hawk. When it is very cold 0 or below the pressure can go way down to 3-5 on start up. After the temp gets up to 160 -180 (cardboard rad blocker) and about 1/2 hour running, if I stop and shut it off for about 10 min, maybe go get coffee, then come back and drain the water line, occasionally some gunk comes out other times not. Then the pressure will climb to 10 or so. That's about as high as it will get when it is very cold untill I have traveled a long ways. Maybe the tank fuel gets warmer. I have checked the input side and get consistant 14psi the same as when the pump was new even when very cold. My filter was only 4k old at the first time, now about 6k and no change. The local diesel guy tells me that the fuel is clouding up and the wax is sticking to the filter. I don't think so. I filled a clear plastic bottle with pump fuel and no PS and even at -15 it is not cloudy at all. I leave this burried inthe snow inthe back of the truck so it is cold all the time. The filter I use installed now is a Wix from NAPA. I don't remember what the previous filter was as it was emerg. install out in the country. No Problems with it. I suspect the Wix and Fleetgard filter are finer and filter better so probably don't flow as well when the fuel is cold and thicker. We do get b2 or b5 biodiesel here as standard so maybe this is part of the problem.

This is just what I'm finding. As it turns out since putting the rad blocker in winter mileage has gone way up. I got 21 mpg last tank and 20 on the 2 previous fills. About 3 mpg better than last year. Same road, same pump and about the same dist. I took it out for 1/2 of the trip just to test it and it dropped 2 mpg for the 100 mile fill up test. It never got above the low end of the mark on the gage. Barely off the peg. -10 deg.