Where's Einstien when you need him?

[jlwelding]

Ok, for those of you who dont know me and my truck observe. I will start by saying my truck is cursed, some here would agree some will tell you he's not a good enough mechanic. My fuel pump is a Airdog 100 when new it ran about 15lbs of pressure at idle, wot it was 14.50, one year later it drops to 13lbs at idle and 12.50 wot. Ok I have other problems other than that but we wont go there yet. So I just accepted that was normal, so while trying to fix other issues one step at a time ( replacing everythink one peace at a time till I fix it or it will be stock again ) I started with fuel pressure hose from pump to isolater. No leaks no cracks in line no slite fuel on fittings or anything.No sharp bends in line,straight shot all the way.And I said to my self this is a waste of time but here gose. So why do I now have 15lbs at idle again and 14.50 a wot? I will throw this at you to, old vp44 needed to be replaced no dout it had little issues and stuff such as dieing for a split second then pick right back up and run, you know the little things in life that make you day. Oh yes I allmost forgot it has never thrown a code excepted the first vp44 about 50k miles ago. Fuel mileage with old vp was 15mpg new vp jumped to 18mpg, today I am at 14.75mpg again. What the !!!!? I will also say the only thing that has not been replaced is the map sensor and the ait everything has been replaced when I say everything thats just it all of it has either been swaped with another truck or bought new, turbo and ecm have been swaped ran for a day then put back the next day. Turbo one day ecm the next day. Cam sensor you name it.Michael, I am thinking if I dont fix this truck I will take a road trip to see you, I now we laughed about it but it is starting to be a reality. If we dont fix it we can make a new Dodge commercial, I am sure you know of some good mountains aroud there. lol

[cajflynn]

Have you checked the basket in the tank?

[Mopar1973Man]

Ok, for those of you who dont know me and my truck observe. I will start by saying my truck is cursed, some here would agree some will tell you he's not a good enough mechanic. My fuel pump is a Airdog 100 when new it ran about 15lbs of pressure at idle, wot it was 14.50, one year later it drops to 13lbs at idle and 12.50 wot.

Not normal... Unless the filter is plugging fast..

Ok I have other problems other than that but we wont go there yet. So I just accepted that was normal, so while trying to fix other issues one step at a time ( replacing everythink one peace at a time till I fix it or it will be stock again ) I started with fuel pressure hose from pump to isolater. No leaks no cracks in line no slite fuel on fittings or anything.No sharp bends in line,straight shot all the way.And I said to my self this is a waste of time but here gose. So why do I now have 15lbs at idle again and 14.50 a wot?

The isolater is causing a big part of your fuel pressure problems. I would yank it out and put a needle valve in and see if that straighten out that problem.

I will throw this at you to, old vp44 needed to be replaced no dout it had little issues and stuff such as dieing for a split second then pick right back up and run, you know the little things in life that make you day.

so we know the VP44 is fresh...

Oh yes I allmost forgot it has never thrown a code excepted the first vp44 about 50k miles ago.

No codes...

Fuel mileage with old vp was 15mpg new vp jumped to 18mpg, today I am at 14.75mpg again. What the !!!!?

Possible you got a bad tank of fuel? Winterized fuels???

I will also say the only thing that has not been replaced is the map sensor and the ait everything has been replaced when I say everything thats just it all of it has either been swaped with another truck or bought new, turbo and ecm have been swaped ran for a day then put back the next day. Turbo one day ecm the next day. Cam sensor you name it.

Most everything is covered...

Michael, I am thinking if I dont fix this truck I will take a road trip to see you, I now we laughed about it but it is starting to be a reality. If we dont fix it we can make a new Dodge commercial, I am sure you know of some good mountains aroud there. lol

As for high mountain there is a peak up here at 9,900 Feet but I'm sure USFS wouldn't like the idea of a Cummins laying out in the woods... Worst part is it would most likely survive the fall and come back to haunt you!

Have you checked the basket in the tank?

Valid idea... I just talked to a guy on the phone with fuel pressure falling to 0 but on a 5 gallon fuel can it runs fine... Is the stock pick up all plugged up?

[LiveOak]

Do you have the Air Dog routed through the OEM fuel cannister or directly to the VP-44? Deteriorated fuel pressure is with all new filters? I agree with the comment on checking the fuel pickup basket. They are not difficult to obstruct with crud that grows in bad fuel. Going in another direction.........have you put a known accurate fuel pressure test gauge on the VP-44 schrader valve and conducted a test run? Reason I ask is that fuel isolators are NOTORIOUS for causing erroneous fuel pressure indication in the cab. I fought this very same problem with my fuel system until I replaced the fuel isolator. The origninal fuel isolator was faulty right out of the box. It would very very gradually leak between the fuel and anti-freeze side of the isolator membrane. I bought my gauge kit from Eric at Vulcan. Eric sent me a new fuel isolator, no charge and that nailed the problem. He later sent me a repair kit for the faulty isolator. The pressure was never low.........just the readings the gauge inside the cab. :rolleyes2: Hope this helps.

[jlwelding]

Fuel mileage with old vp was 15mpg new vp jumped to 18mpg, today I am at 14.75mpg again. What the !!!!?Possible you got a bad tank of fuel? Winterized fuels???No winter fuel in south central Tx that I know of.Deteriorated fuel pressure is with all new filters? Yes no change.I agree with the comment on checking the fuel pickup basket. They are not difficult to obstruct with crud that grows in bad fuel. That is something I thought about but didnt follow up on it. I think I will now.Going in another direction.........have you put a known accurate fuel pressure test gauge on the VP-44 schrader valve and conducted a test run? Reason I ask is that fuel isolators are NOTORIOUS for causing erroneous fuel pressure indication in the cab. I fought this very same problem with my fuel system until I replaced the fuel isolator. The origninal fuel isolator was faulty right out of the box. It would very very gradually leak between the fuel and anti-freeze side of the isolator membrane. I bought my gauge kit from Eric at Vulcan. Eric sent me a new fuel isolator, no charge and that nailed the problem. He later sent me a repair kit for the faulty isolator. I will in the morning. My fuel pump is a Airdog 100 when new it ran about 15lbs of pressure at idle, wot it was 14.50, one year later it drops to 13lbs at idle and 12.50 wot.Not normal... Unless the filter is plugging fast..Temp. yesterday when I replaced hose was about 58.I used to replace filters at every 10k but when I went to Airdog and just washed out primary filter at 10k.In the year and a half I have been running Airdog I have replaced both filters twice, and never noticed any differance or fuel pressure diffrance.Do you have the Air Dog routed through the OEM fuel cannister or directly to the VP-44? No, it is ran from tank to filters to vp44.I have a thought , is there any way the return lines in the head or the lines coming out of head get stoped up?Also I noticed a stronger fuel smell today, checked for leaks and nothing. That is what made me think return line stoped up.I tried to answer questions in order

[LiveOak]

Also I noticed a stronger fuel smell today, checked for leaks and nothing. That is what made me think return line stoped up. I tried to answer questions in order

This may possibly be another option. When I installed the Air Dog, almost immeadiately the fuel pressure would periodically go upto 24 psi but would gradually decrease down to around 20 psi with extended running of the truck. I called Pure Flow and talked to them and one of the techs suggested that that fuel return valve in the VP-44 was sticking shut and causing the increased pressure. He told me that this happens sometimes and usually the return valve will let loose and open up, thus reducing the pressure back to the factor set pressure of approx. 18 psi. We were all set to make a pressure out put adjustment on the Air Dog when the pressure dropped to the 18 psi range by itself. Apparently the return valve was stuck shut from so many years of never being used with the weak Carter lift pump but the Air Dog dislodged it. In your case, it could be that return valve us stuck open. This is not a very likely possibility. I would check that other options first. Have you called Pure Flow and talked to them about this issue?

[jlwelding]

I agree with the comment on checking the fuel pickup basket. They are not difficult to obstruct with crud that grows in bad fuel. I have a flat bed and the tank is real easy to get to, do I need to drop tank? I was thinking I could just open the top and clean that way.

[LiveOak]

I agree with the comment on checking the fuel pickup basket. They are not difficult to obstruct with crud that grows in bad fuel. I have a flat bed and the tank is real easy to get to, do I need to drop tank? I was thinking I could just open the top and clean that way.

Not sure exactly how much clearance you have between the tank top and the truck bed. The basket is about the same height as the tank, if you can open the tank up and lift the basket up out of the tank with out dropping the tank, go for it. I don't think this is going to be possible but your case may be different. In the event the tank is full of crud and pieces of junk like mine was, it is nice to have the tank removed with the basket out so you can turn it upside down and clean out the crap with compressed air and spray cleaners. The polyester fabric on the fuel basket can be difficult to clean up if it gets contaminated with goey gelatinous crud. In my case we had to cut the polyester fabric out of the fuel basket to accomdate a 1/2 inch tank draw straw kit.

[LiveOak]

Come to think of it, if your fuel basket is really hosed up, you may want to just replace it with one of these instead since you already have the Air Dog installed. Kinda pricey though. http://www.vulcanperformance.com/DrawStraw-V-HiFlow-p/jlfmds.htm One of these draw straw versions may be another option as well: http://www.vulcanperformance.com/category-s/220.htm

[jlwelding]

I agree, better to drop tank because I know my luck, it will have crud in it.The complete basket deal my be the way to go I think,you get new gasket and not spend time cleaning,just slap it in and go.