jeephauler

I finished up the install tonight and started the truck. My pressure gauge goes to 19psi and holds steady for 6 seconds then slowly begins to climb for 7 seconds and hits 25psi, then drops back quickly to 20psi, then begins to climb for 7 seconds and hits 29psi, then drops back to 20, then climbs again gradually and pegged my gauge at 30 when I shut her down.

Any suggestions?

I did the fuel module upgrade and even tore the tank back out to make sure I did not have any restrictions or kinked return lines. Ive bled the system and the isolator for my gauge. Im at a loss for what to try next.

Ill be giving Airdog a call in the morning to see what they suggest.

jeephauler

Airdog said there must be a block or restriction on the return line from the pump.

I had already double checked the line for kinks and dropped the tank again to blow thru the factory supply fitting to make sure everything was clear. Guess Ill be taking the line off and running it to a bucket tonight to see how flow is and try to determine if its a bad line or something in the pump base.

My luck Ill be the only one who has ever gotten a bad line!

carl48

you need to take that pos airdog off and put in the trash and go back stock. the tank pump is 10 times more reliable than the airdog. if you decide to keep the airdog, make a bypass hose up to carry with you so when it fails you can bypass it and not have to walk home and then do not get in a hurry about replacing it or putting the stock one back in, the cp3 does not need a lift pump. just wait until weather is warm and tank is low.

jeephauler

Stock was not cutting it anymore as I am dropping to 0psi at WOT with an idle of 8psi.

UPDATE-I pulled the return line off the tank tonight and put it in a fuel container and it appeared to fix the high pressure fluctuation issue, however the fuel was only coming out in spurts and hardly any at all. The line was running totally downhill to the ground rather than slightly up hill to the tank when hooked up. I am actually thinking the pump is not pushing enough to get the fuel uphill to return to the tank.

I only had 5psi on the gauge though so I started playing with the regulator screw to see if I could get the pressure to increase. I was only able to get the pressure to a max of 14 with the regulator screwed all the way in.

I am definitely thinking that there is a pump issue now. Another call to Airdog tomorrow to request they send me a replacement to give a try.

carl48

I can see your bent on keeping the airdog for some reason. before you change it out temporarily run a 10 gauge wire directly to the battery and to the pump and see if it cures the problem. the truck wiring used the smallest wiring possible to save money. we have built several relay circuits for people with airdog or raptor problems similar to yours. one very noticeable giveaway is the pressure will vary with the grid heater. the lower voltage makes the pump fail that much faster. you should have bought a brushless or mechanical pump but if this fixes the problem pm me and I will send diode and relay info along with schematic. while you are at it plumb a ball valve in around the airdog so every time it fails all you have to do is turn the valve on and be on your way.

jeephauler

Airdog is sending me another pump which will be here Friday. We will see if that fixes the issues.

carl48

set the pressure at 8 psi

jhenson

8 psi???? Why so low? I understand that lower pressures = higher flow but my 6 yr old AD150 has been flawless running 18psi with big injectors and programmer. Good info on the wiring.....I never even gave any thought as to why the pressure would drop when the grid would cycle. Once I deleted my grid the fluctuations quit.

carl48

the cp3 works entirely different than a vp44 the vp44 must have 16 psi to lube and cool and has heavy return flow to the tank. the cp3 was designed for NO lift pump. it has full life and output with input between MINUS 5 psi and + 20 psi. the stock oem pump is set at 7 to 8 psi. the duramax nor none of my industrial engines have lift pumps. lower pressures does not = higher flow. you do need to add better filtering and now is the time to do it. email me if you want how to and drawing. the reason I said to plumb in a ball valve is so when the pos airdog quits it plugs the line up to where the cp3 can not pull any fuel through it, turn the ball valve on and drive it a 1,000,000 miles and then replace the airdog with a brushless pump. that expert you are talking to is a idiot.

Sam9290

Hello Carl48,

Do you have a recommendation on a particular brushless pump to purchase?

carl48

sam I use one made in Germany but I can not remember the brand, it has been about five years since I changed one out. next week I will look at one of my 03's that I know has one and see if I can get it for you. the usa made ones that I see are expensive but I have not been looking lately. federal signal under the carter brand has one and fuelab has one. do a search and see if you can find some, I bet china has a boatload of them.

Lary Ellis (Top)

We have the brushless fuel pumps right here in the DTR Performance Shop!

http://www.dodge-diesel.org/dodgefuelpumps.html

Sam9290

Thanks for the information guys, I 'm looking at the fuel lab 100 brushless pump.