Low Fp When Cold

[milenko]

Hello All.  I am relatively new to Cummins but have owned my 99 Dodge for a couple years.  It has 265,000 miles on him.  Everything is stock except the previous owner installed an edge EZ and I installed boost and an electronic fuel pressure gauges.  When I installed the gauge last year I installed the t-fitting to avoid the hammer effect.  I have a question.  Here over the past couple weeks (it has been 0-20 F here) when I start up the truck in the AM the pressure will be in the single digits for about 5 seconds and then jump up to 13 or 14 psi.  Do you think this is just because the diesel is cold, or is my lift pump about to quit?  It is a stock LP and I plan on changing it this summer when the weather is a bit nicer.   Thanks

[Ilikeoldfords]

When you say T fitting, do you mean a needle valve? Just because of how many problems people have had, I would want to verify your electronic fuel pressure gauge with a mechanical one. You never know when the sender will go bad on ya. That being said, are you running any kind of antigel in your fuel? Anything lower than about 25 degrees and I always make sure I am either running diesel #1 or at least a good antigel in the fuel.

[Ilikeoldfords]

Also, welcome to the forum!!! Stick around and have a beer   It will be helpful down the road if you fill in your signature with some info on your truck. You can do that by going up to your profile on the top right of the screen.

[TFaoro]

 Get that signature filled in so we can help you!

 

Mine did sort of the same thing when it was starting to gel (0 to -10 deg).... Try putting some additive in. You might have slight gelling in a few the lines, connections, or filter.

[milenko]

Hey guys, sorry, thought I filled in my profile information.  I have used this site in the past, but only the 911 forum cause my tranny broked.  Turned out I needed  a new one.  I mostly am a lurker on this site, cause all the info I could possible use was found using the search function.  In any case,

 

When you say T fitting, do you mean a needle valve? Just because of how many problems people have had, I would want to verify your electronic fuel pressure gauge with a mechanical one. You never know when the sender will go bad on ya. That being said, are you running any kind of antigel in your fuel? Anything lower than about 25 degrees and I always make sure I am either running diesel #1 or at least a good antigel in the fuel.

 

Yes, I installed a needle valve because I read on here that it is required so I don't destroy my sending unit.  Is there a mechanical valve I can rent somewhere, last I checked they were around 100 bucks to buy, and I don't have that much spare change to buy a gauge to make sure my gauge is working properly.

 

As for additives. I am currently experimenting with different additives.  I have used 2 cycle oil, Dieselpower, diesel 911, and another diesel additive that comes in a clear bottle at truck stops, diesel surge maybe (sorry I dont remember the brand).  I have found that they are all essentially identicle in terms of startup and drivability. 

[Ilikeoldfords]

Good on the needle valve. A decent mechanical fuel pressure gauge can be had for about $50. I think mike has a link to it somewhere. You may also be able to rent one from the local oriellys or autozone. It really sounds to me like you got some gelled fuel possibly. Try changing your fuel filter out. May have sludged up on ya.

Edited February 23, 2014 by Ilikeoldfords

[mulcher812]

I picked up an 1/8npt 0-30psi gauge from Napa for $20 It will install right on top of your filter housing. Remember to use the yellow Teflon tape on fuel lines the diesel has a tendency to eat away the white stuff and cause leaks...

[hex0rz]

I think your fine. You can try and get something to doublecheck that your FP gauge is working properly, but I don't think you are experiencing anything out of the norm.

 

I notice my FP stays low initally until the grids cycle off. See if the FP is correlating with the grids cycling. Mine is an AD so its not as low a pressure as yours but it still seems like this might be the case.

 

BTW, I have gone down to subzero temperature and have not added a single additive and have yet to experience any gelling. Pump says #2 with no winter blend and may contain up to 5% bio.

 

I use 2-stroke all the time, so I dunno if you would consider it an additive.

 

How you can really tell if your LP is going to die is if pressures are constantly below 10 and goes to 0 on good to full throttle situations. Thankfully, my LP on here when I bought the truck did not destroy my vp44 as that was the case with mine. Dunno how the IP lasted so long without any pressures!

[milenko]

I picked up an 1/8npt 0-30psi gauge from Napa for $20 It will install right on top of your filter housing. Remember to use the yellow Teflon tape on fuel lines the diesel has a tendency to eat away the white stuff and cause leaks...

 

Wow, really?  I didn't even know they make yellow teflon tape.  BTW, I love the fact that the 99's had two bolts on the top of the fuel filter housing, it made installing the pressure gauge a breeze. 

 

How you can really tell if your LP is going to die is if pressures are constantly below 10 and goes to 0 on good to full throttle situations. Thankfully, my LP on here when I bought the truck did not destroy my vp44 as that was the case with mine. Dunno how the IP lasted so long without any pressures!

 

Thank you for the information.  That makes me feel much better.  Still planning on switching out the LP this summer for some cheap insurance, but am happy I don't have to do it while laying in the snow.

[LiveOak]

Try checking your pressure with a manual gauge and verify pressures. 

 

http://www.vulcanperformance.com/VPMAX-Fuel-Pressure-Tester-Test-Gauge-Schrader-p/fpt.htm

 

During extreme cold weather diesel fuel will have a higher viscosity (enough to cause a lower pressure reading) until the fuel heater in the fuel filter housing warms the fuel up. 

 

Another cause (probably not in your case as you said you are running an electric gauge) is for those who run a manual fuel pressure gauge, the fuel pressure isolator divider will become much stiffer due to the cold temperature being made of rubber and cause an low pressure reading. 

 

Not knowing for sure but I suppose a fuel pressure sending unit for an electrical gauge could be effected by extreme cold weather, hence the need to verify with a manual pressure test gauge.