Engine/Transmission (1998.5 - 2002) In-tank pump responses only

[jcwehking]

Recently, during -5 degree temps, after a few seconds of running, my fuel pressure drops to zero at idle and doesn't come up to the normal 8 psi until 10 minutes or so of runtime. I assume the fuel filter heater is getting the fuel warmed and moving again. I'm using blended fuel that says is good to negative 20 degrees. This is the 2nd occurance. Once last winter and now again this year. Has anyone else with the in-tank pump experienced this same problem? I've pulled the filter out and can see the build up on the filter media. I question if the lower fuel pressure from this type of pump is not enough to push the fuel through the slight geling that collects on the filter media or have I just had bad luck and getting fuel that isn't blended to the specs claimed?



Please no replies about what pump should or shouldn't be used. Everyone know we don't need to go there.

 

[MSimes]

I live in sunny CA and run Stanadyne in case I need to run up the hill. haven't had a problem.

 

[blacksheepdiesel]

Well, ok we don't have to talk about what pump should or shouldn't be used, but the fact is the in-tank pump shouldn't be use because it is barely sufficient during warm temps, let alone colder temps like you experienced with even a new fuel filter, let alone one that may be partially plugged. Based on what you describe one or both of two things is happening.
1. In-tank pump is too weak for parameters experienced.
2. There is air in the pressure unit sending line that is exacerbating the situation. Where is the sending unit tapped into the supply line? Before or after the filter?

I doubt that it is #2 because the psi initially comes up to normal, then backs down.

Are you running any anti-gel? I definitely would seeing the temps you see.

I know what I would do if I were you.

Godspeed,
Trent

 

[JDriscoll]

Are you running an isolator on your fuel pressure guage? Mine has done the same thing twice this week. I have the FASS pump on my truck and both times I could hear the pump running, once it warmed up a little bit the pressure reading jumped back up to where it should be. I was thinking the problem was with the guage and not the lift pump. My guage is tapped into the banjo bolt on the VP44

 

[jcwehking]

JDriscoll, interesting thought regarding the sending unit. Especially since I have not heard of any failures of the in-tank pump, cold or warm. The sender is coming off the schrader valve to the electronic sending unit, so its after the filter. I added a bottle of 911 to the tank but the pressure was already up to normal when I added it. Temp hasn't dropped back down below zero since so don't know if the 911 will help.

 

[Duluth Diesel]

If you have fuel gel issues, your fuel will restrict on the fuel filter face. Run a good anti-gel like AMSOIL Cold Flow or Power Service. An anti-gel is a copolymer, which prevents the paraffin molecules from bonding to eachother. An anti-gel won't change the cloud point of your fuel but it will lower the gel point. When petroleum fuel cools, the paraffin (wax) molecules bond and create crystal structures. The cooler the fuel gets, the more paraffin molecules bond together, forming bigger and bigger molecules. These large paraffin crystals, or gel, are what restrict up on your fuel filter face, starving your engine of fuel and fuel pressure. An anti-gel, acting as a copolymer, bonds to the paraffin molecules. While the paraffin molecules still bond somewhat (cloudy fuel), they are unable to form large crystal structures. This allows the cold diesel fuel to still flow through your fuel filter. This is important anti-gel theory to understand, in case you are glazing over in your chair. The reason this is important to understand is because if you're running a factory 10 or 7 micron fuel filter, a normal dose of anti-gel will prevent enough paraffin bonding to get fuel through that filter. But what I've been seeing the last few winters are people who are running FASS or Airdog or other lift pumps with 2 micron fuel filters are having more fuel gel issues and fuel pressure issues in the cold. Since a 2 micron fuel filter is less tolorant of crystal structures passing through, it takes a heavier dose of anti-gel to feed petroleum diesel fuel through a 2 micron filter.



I run AMSOIL Cold Flow and have never had a fuel gel issue, knock on wood, since 2002 when I bought my Cummins new.



-Chuck

 

[jcwehking]

How is an anti-gel different from a blended fuel that is sold through the pump? Don't you get the same thing?

 

[mhenon]

I had a similar problem after picking up a bad load of fuel. I think there was water in the fuel as I couldn't see anything on the filter media. Pressure dropped from 8psi to about 4psi shortly after running. I changed filters 3 times before refueling at a different station and never had the problem again.



So to answer your question. . yes you will see lower pressure with any kind of restriction in the system. Mine kept going down the road like yours but I kept my eye glued to the gauge. I still have that intank pump but it's now used as a low pressure pusher to feed my main LP. The duo can put out 26psi all day though I keep it bypassed to run at 14psi. No problems now for 2 1/2 years.



Good luck.

Mike

 

[Duluth Diesel]

How is an anti-gel different from a blended fuel that is sold through the pump? Don't you get the same thing?

There are no promises in the fuel at the pump. If it is simply blended #1 and #2, you better pray that they got the mixture right for the temperatures.



If you are talking about #2 with a cold flow inproved added at the refinery or fuel rack, then you are also trusting a lot of variables that can fail. Every load of diesel fuel is mixed while it goes onto the tanker truck that is heading to the fuel station. It is mixed individually, one load at a time. The refinery or tank farm does not store blended fuel in bulk. Fuel companies do not transfer mixed fuel by pipeline. They only mix it per truck load. So this means you're trusting the guy doing the blending or the electronics and injectors doing the blending. Usually this all works and most people don't have problems. But every winter I hear countless fuel gelling issues arise due to improperly blended fuel getting delivered to a station. If you add your own anti-gel, you'll never have a gel issue. I add AMSOIL Diesel Concentrate with Cold Flow Improved to every load of fuel I buy and I haven't had a problem. If you don't add an anti-gel product in cold weather to every load of fuel, you are simply trusting someone or something else with your truck's fuel and by rolling the dice you eventually will discover that you can get a bad load of fuel. The only person I trust to blend my fuel is me.



-Chuck

 

[Ncostello]

Use Stanadyne when its below freezing. If not all year long anyhow.



Don't believe me? Take diesel in a jar and leave it out all night at -13F. The next morning observe the yellow, diesel slush puppy. Take a capful of Performance Formula and pour in. Watch it quickly, nearly instantly, return to its normal state and color of light gold.



At -5F, untreated fuel might definately be causing fuel pressure problems. Especially if its not exactly a liquid any longer.

 

[BHubbard]

Stay away from additives,and only run bio-diesel in the warm temps,if at all. The in tank pump is junk and it will lead to a vp-44 failure sooner than later. I paid over $500 to have a shop put one in after my lift pump failed,I removed it a month later and installed a premium pump (fass) and stoped using bio-diesel and additives. 70,000mi later and I am happy that I have no more fuel problems.

 

[Jacobe]

how did you hook up the in tank pump and outside lift pump together. My lift pump was replaced with a in tank pump while under warrenty. My fuel mileage dropped off really bad. I want to change back .

 

[BHubbard]

You have to drop the tank ,remove in tank pump,replace with draw straw. Then mount new pump on frame rail near/below tank. I understad fass now makes a direct replacement fuel pump,not sure where that one mounts,they say its a bit less expensive than a full kit. I mounted a 150gph pump only on my frame,and pumped fuel through the stock filter system. I know its not as good as the water seperator/filter,that goes directly into your injection pump,maby almost 2 bills less?

Check out genos garage,they have a few nice pumps available.

 

[WestTN]

[QUOTE=blacksheepdiesel;



I doubt that it is #2 because the psi initially comes up to normal, then backs down.







My old truck gelled once after filling up at a truck stop that had not treated their fuel properly. It WAS #2 and the temperature was 15 degF below zero. . It takes a liitle while to choke off the fuel supply. In my case, it was about 30 seconds. The engine idle speed was usually about 800 rpms. When started it went to 800 and shortly after, it ramped down slowly to zero. Incidentally, it would not respond to the throttle.

 

[blacksheepdiesel]

Dennis,

Guess I didn't make clear I was referring to the item #2 earlier in my post, not #2 diesel fuel.

I also had the same thing happen that you describe. It was in a 1985 Buick Century with the V6 diesel and ironically it happend in Murfreesboro, TN, same state you are from. Hhhmmm, wonder if there is a conspiracy going on in TN!!!

Godspeed,
Trent

 

[Jacobe]

thank you for the information.

JLJ