After running the truck for 100 miles or so, I felt the vp44 and it felt kinda hot. I know if the LP is working well, enough fuel should go thru the IP to cool it. What should the vp44 temp be while running? Thanks in advance for any info.

 

No real way to monitor the VP temps that I'm aware of.

How do you know the LP is working?

Just make sure you have a FP guage to ensure you have good flow. Just because you can hear it does not mean it is working. Don't guess, get a FP guage, and keep your tank 1/2 full.

 

My fuel temps at the VP are around 130* IIRC last time I checked. This is after the fuel has warmed up and cycled through already.

 

I've read that proper fp will keep the vp44 from burning up. Is this true? After I've changed my fuel filter and refilled the housing, wouldn't the fp have to work to regain prime?

 

Yes, when you change the filter you should cycle the lift pump about three times. Just turn your key on, let the "wait to start" light to shut off, turn the key back to off, and repeat two more times. You should be able to hear the lift pump running some and it should fire right up on the 4th try. If your lift pump is not working it will be hard to get the truck started.

The VP44 is going to get warm, it's in the engine compartment connected to the engine that is running 190* coolant temp. YOur fuel is 100*+ depending on ambient temps. Don't worry about it.

 

Get a fuel pressure guage installed right away. Hearing the LP does not mean it is pumping.

 

I assume you mean the fuel temp running through the VP-44.
Lots of research has been done on this subject... especially when excessive temps were suspected of causing VP-44 failures. Temps were measures at fuel line into VP44, return lines after VP44, etc.

Don't remember all the data but the summary was that while running, fuel temps, and therefore VP44temps were very consistant and not a problem... under almost all conditions.

Problems arose after shutdown, as I recall, with a heat soak factor of +50*F being the average found.

RJ

 

130* F is about what mine operates at on a typical summer day as well. The DRBIII scan tool reads a myriad of sensors and incoming fuel temp is one of them. IAT is another and it typically reads around 130* F too. I know there are other factors involved, but by adding the fuel temp to the IAT you get 260* F which is about where EGT's should be at idle. Hmmm, interesting stuff.

 

There is a better way of doing this. When you simply turn the key on, the lift pump is only going to run for three seconds. If you leave the key on and just bump the starter, then the lift pump will stay on for thirty seconds.
Then you have to turn the key off for 30 - 60 seconds to start the cycle over again.

 

What rjohnson said. Heatsoak after shutdown is the real problem, along with thermal cycling over time. The "Fedex" and "post-Fedex" electronic packages are designed to resist the sort of deterioration that accompanies these heat problems, but they're not fail-proof.

I believe City Diesel is stil experimenting with a thermal solution to the problem, but they have no product on the market yet.

 

If the board is burning up then moving the board to the fender like Stanadyne did would be a fix as well as designing a high temp board like the Fedex piece.
If the fuel control "coil" inside the VP is getting hot and shorting, we'll still have a problem.
Maybe a cooler with a timer/temperature switch to let the lift pump run extra after shutdown. Mine runs much cooler with the cheapo fuel cooler but it'll still get very warm during the shutdown-heat soak.

 

I've been hauling fema campers since Katrina, and I will be hauling between Baton Rouge and Hope,AR from friday til monday. If the heatsoak after shutdown is a problem, will it be better to just keep the engine running all weekend? If I use my high idle stick and keep rpm's above 1200, it will be ok, right?

 

I would not worry about it that much, but if it concerns you.... park into the wind, when you can and raise your hood.

Some have installed timed blowers for after shutdown. I have a shop fan running all summer long in my garage and I do point it at the front end when I get home at the end of the day.
Does it do any good..... who knows?

RJ

 

My understanding is that the seals inside the VP44s fail more often than the electronics due to heat soak... any techs who know care to weigh in?

Roland - I don't think airflow is significant in alleviating the heat soak. My testing shows that IP temps are much more sensitive to the fuel temperature and rate of flow than the ambient airflow or temperature, which is why the heat soak is so rough on them - no coolant (fuel) is being circulated.

WadeCool - the cummins isn't going to be washing the oil off the cylinders when it's warm outside!

Clunk - will the VP44 allow fuel to pass through it back to the tank if the engine isn't running?

smokindog - I've seen CP3 temps as high as 175*F, and the VP44 run even hotter; those temps are outside the design envelope of any non-hardened electronics, and on the ragged edge of the seal materials commonly used by OEMs.

 

I wouldn't let it idle all the time but filling the fuel tank before shutting down would get cooler fuel to the IP for shutdown. Mine doesn't seem to get as warm when I leave the hood open after shutdown but you have to beware of battery thieves unless you can keep it in sight.
Some who've had hot IP trouble have revived them by pouring cool water right over the top of the IP.