Engine/Transmission (1998.5 - 2002) Please help with my fp numbers

[BDR]

Well I did some searching/reading and keep finding that everybody is running a higher fuel pressure than what I see with my truck. What's normal? I'm at 13-14 psi at the most. But I read about people with 15-20 psi. And now that it's cold I'm down to like 10 psi when my truck is warm, and it will stay low all day long. What happened? What would cause a 4 psi drop, the cold, bad VP? Please any help would be great, kinda worried. Thanks

 

[Supermod56]

Are you talking about idle pressure? If you have 10 at idle, that's a little low, normal with a stock L/P is around 13-14, and nothing lower than 7-8 at WOT. The higher pressures are seen with a FASS, AirDog, etc. My RASP runs at 15 psi all the time, no matter what the throttle position. If your fuel filter is new, the L/P is probably going south. Mine with the stock pump stayed the same even in the winter.



Tom

 

[BDR]

Well I'm running the AirDog, and yes at idle my fp is 10-11 psi.

 

[Supermod56]

Might be something wrong with the regulator, dirty, stuck, etc. I would think it has some type of pressure regulator, but I don't know. The RASP uses a bypass in a seperate return line back to the tank. Maybe someone with the Dog can chime in??



Tom

 

[Rattlin_Ram]

My fuel pressure is down recently due to the cold as well. Normally I'm around 14-15psi at idle now I'm around 12.

 

[Devil Black Diesel]

I just had a 10psi drop and I thought I lost a lift pump or pusher pump. It turned out to be a very dirty fuel filter, and the isolator on my FP guage did not have enough antifreeze in it. I replaced my FF and filled the FP isolator with antifreeze and I'm back up to 24psi at idle.

 

[BDR]

The most I have ever seen was 14psi, how is it possible your running 24psi?

 

[dmagenau]

i read on a post somewhere that anything over 14psi is to much for the VP 44, it opens some relief valve. I also read that volume is more important than pressure. I don't know if there is any truth to it. I sure would like to know before i put an aftermarket pusher pump on. I know that with some of the systems psi can be regulated by adjusting the length of a spring. I just put in a FP guage a couple weeks ago, and the numbers are scary.



Idle 11. 5 psi

Highway 6. 5 psi

WOT <4. 0

 

[Devil Black Diesel]

I have the stock LP which was producing 15psi and my carter Carter pusher pump was producing another 9psi (we tested them both separately while troubleshooting my low FP).



As far as having too much FP to the VP44, I have read those threads as well and I don't know what to believe. There are tons of other guys out there who have been running the exact same setup I have for several years with no problems and no dead VP44's so that proves the "too much FP" theory to be false.



It seems like VP44 failures are soo random you can't really put a finger on what really causes them to die.

 

[KTobin]

Many people here are running with aftermarket setups. The stock LP idled at 14 to 15 lbs on a good day. I personally run 20 psi due to a 6 lb pusher running in series with my stock LP, and have been doing so for over 25K miles with out problem. When it gets cold, the pressure drop around your FF increases and this accounts for your drop in pressure. At freezing temperatures, I will get a 5 pound drop around my filter resulting in 15 psi at the VP. I only run #2 summer blend. This in itself, I believe, is grounds enough for running a pusher, not to mention the benefit of taking a lot of the load off the stock LP. However, if you have the Airdog, as you say, Run a full tank of winter blend with quart of any anti gelling additive and see if increases your psi. This should relieve any worry of the VP going south if it increases your psi. I believe you said you had a new FF?



Kevin

 

[BDR]

I haven't changed mine yet, might be time. How often would be good? I haven't heard any mile intervals.

 

[KTobin]

I change my FF every 15K or whenever I'm troubleshooting the fuel system. For $10 you can have a new filter AND eliminate one link in the trouble shooting chain.



Kevin

 

[BDR]

Along with changing the filter is there anything else that might cayse a drop in psi?

 

[KTobin]

Sure, I can think of about 20 off the top of my head, but you're only talking about a couple pounds and only since it got cold. Change the filter, thin out the fuel, as I mentioned, and see what happens. These are cheep trouble shooting proceedures. If that dosn't work, then your Airdog needs attention.



Kevin

 

[BDR]

Cool, thanks for the help! I'll give it a look. The temps are coming back up here so that might help. The -13 degrees could have been a big factor.