swordfish

When installing the Air Dog 150 with the drawstraw what do you guys do with the factory fuel pickup line that uses the dorman fitting? Does it need to be plugged and sealed or what? Just curious what others have done. I am having a hard start when warm issue since I installed the Air dog. My pressure is at 23 at idle and 21 at WOT. Not sure why my pressure is so high when others talk about being in the 17 range at idle. I have tried calling Pure Flow twice and left messages with no return call. I just want to make sure I did the install correctly. The factory pickup line I crimped off, but I know is not sealed. Not sure if there needs to be a certain amount of vacuum in the tank to keep fuel from coming back to the tank when the truck is off or what. Just trying to rule everything I did out to figure out why I have this hard starting issue at operating temp. I replaced the ECT sensor because of other threads I have read. That helped a little, but it still struggles to start a little. Any transfer of knowledge on how the fuel system should work would be great...ie sealed tank or not. Thanks Guys!!

swordfish

nickg

some trucks struggle to start with high fuel pressure, as a test pull the fuse on the airdog, and seel if it starts on the first crank, as soon as it starts shut it off, now you will know if its a high pressure issue
there is a thread to wire in a relay to kill the airdog during cranking, then allow it to start once the engine starts
or contact AD, and get a different pressure relief spring to drop fuel pressure.

there is susposed to be a small amount of vacuum in the tank to aid in air extraction from the fuel, too much(faulty fuelcap/plugged tank vent)will suck the fuel from the VP/filters when the veh sits for any length of time, especially if there are any air leaks in the return side of the fuel system (cross over tbe o-rings/fitting at back of head/ return lines etc)

swordfish

Thanks nickg for your response. I have unplugged the Air Dog and tried to start and it started right off and I quickly shut it down. The Air Dog that I have plugs into the stock lift pump harness and also has a relay attached to it. When I turn the key ON the pump primes then stops then starts again when the vehicle starts. I believe that is what you are referring to when you say to install a relay. I have checked my fittings and put a wrench on them and I do not see any leaks.

swordfish

nickg

no there is another mod that interupts the signal to the AD relay so that on start up the fuel pump is turned off,
I'll try to find it for you
usually the air leaks can't be seen, symptoms occur on a cold/sat over night, first start of the day, and confirmed by leaving fuel cap loose or parking nose down hill, this keeps the fuel from being syphoned back to tank.
you problem is too much fuel pressure on start up, as mentioned contact pureflow, I'm sure they will send you a lower pressure relief spring

nickg

here is a link, it has a wiring diagram, most info on page 3, but read whole thread anyway

http://www.cumminsforum.com/forum/98...tarting-3.html

swordfish

Thanks NickG,
I talked to Pureflow yesterday and they said they had some issues with pumps around the time I got mine. He told me there should be a damper on the return to tank that is not letting enough fuel through and so it is causing my high pressures to the pump. I took the return line off last night, removed the AN connector, removed the spring and check ball, but found no "damper". I just put another call into them to clarify what they are saying and left a message. I guess I am not sure what they are talking about. I looked for schematics for the pump and found nothing. The guy said to take a hammer and punch to make the outlet bigger....Make sense? I will read the post on the Relay...if their advice won't get it fixed I will go that route. I would rather it work correctly then to have to "rig" it up.


swordfish

swordfish

NickG, read through the thread and I was wondering since I have access to the pressure spring if I could just try to cut it down to lower my pressure. I just don't know which end to cut and how much. I would like to go that route first as I am a stronger mechanic than electrician and trying to follow that diagram was a bit confusing to me. I have never had a good electrician teacher in my life, just good wrench turners. Thanks so much for all the information and your help on this. I can't tell you how much I appreciate it.

swordfish

swordfish

just as a follow up, I talked to PureFlow yesterday and I finally got clarification on what I was supposed to modify to drop my pressure. I guess they had some issues with the return section that is installed in the filler neck. The guy from PureFlow wanted me to take a punch to the flap that is on the inside of the filler neck section where the fuel is returned to bend it and give a little more flow. That helped to drop my pressure by 2 PSI, but I am still at 20 - 21 when idling. I suppose I could take a drill and drill out the other half of the inlet as the hole is only half open, but not sure how that would affect fuel coming back into the filler neck and shooting straight at the opposite wall instead of being diverted down the neck. I have placed another call to find out what they have done to rectify the problem in their current product. Hopefully they will have an answer. I will keep you posted on what they say.

swordfish

swordfish

just as an update, I talked to airdog again after I couldn't get my pressure down. They instructed me to cut down the spring. I did so in increments to make sure I didn't take too much. I finally got it down to 15 psi at idle. No more hard start for me that I have seen. Hopefully it will stay like that. Thanks for all your guys' help and suggestions.

swordfish