OK I've put a Timbo APPS on and a noise isolator. That took care of the check engine code, however, it is still turning over a while before it wants to fire. Sometimes I have to crank it 2 or 3 times for about 3-4 seconds each time before she fires. I don't have anymore codes going off. I'm thinking that it is losing its prime of fuel. Could the airdog 150 be causing this? Before the sensor went bad it was starting fine, suggestions??

if air is entering the fuel system, then yes. when i noticed that i was having longer than normal starts, air was entering the system. the plug on my tapped 90*(vulcan big line kit) at the vp44 had worked itself slightly loose(but was still way more than hand tight). after i tightened it up my starting times were back to normal.

Whats your fuel pressure while its cranking? If it below 7 PSI you got air in the system or a lift pump problem...

i dont know how or why but after i installed my timbo apps i had the exact same problem. i would hit my remote start and it would spin excessivley before firing but as time went by it corrected itself and during this time i searched for fuel leaks, sucking air into fuel system, and fuel pressure. never found a problem

Hey,That sounds like what mine did when the VP went out.... Twice!! No codes, just hard starting, then just no start!:cry:Check for air leaks first, but I would try to plan for a VP. Maybe you'll luck out and be something easy, I'll keep you in my thoughts!:thumbup2:Later,Winslow

I don't have a pressure gauge on it ,just a low fuel pressure light so I would have to put a pressure tester on it to find out the pressure when cranking. I can't see it being the lift pump. That Air Dog system is only about 3 months old. I have noticed that it has no problem in the morning when it's still cold but after its warmed up is when it has the problem.

I don't have a pressure gauge on it ,just a low fuel pressure light so I would have to put a pressure tester on it to find out the pressure when cranking. I can't see it being the lift pump. That Air Dog system is only about 3 months old. I have noticed that it has no problem in the morning when it's still cold but after its warmed up is when it has the problem.

I suggest installating a fuel pressure test gauge and see what your cranking fuel pressure is. http://www.vulcanperformance.com/Fuel-Pressure-Tester-with-Schrader-Connection-p/fpt.htm If it is too high, this can cause hard starting. http://www.bluechipdiesel.com/vp44diagnostichelp.html

It seems my problem is fixed, I unplugged the lift pump and it started right up. So I put a switch in the cab to turn the pump on and off but heres the strange thing, I also had to fix my main ground cables going to the batteries, they were loose. And now I don't need to turn the lift pump off before starting, its working and starting fine, so I'm not really sure if it was a pressure thing from the lift pump or just bad ground connections. Either way I'm just glad its working right . Thanks for the info!

Sounds like your AirDog fuel pressure may a bit high. You might want to call Pure Flow Tech. and get some help on shimming down or adjusting the pressure to within acceptable limits. Too high a fuel pressue can damage the injector pump. Best to fix it right and not have any more problems.

It seems my problem is fixed, I unplugged the lift pump and it started right up. So I put a switch in the cab to turn the pump on and off but heres the strange thing, I also had to fix my main ground cables going to the batteries, they were loose. And now I don't need to turn the lift pump off before starting, its working and starting fine, so I'm not really sure if it was a pressure thing from the lift pump or just bad ground connections. Either way I'm just glad its working right . Thanks for the info!

Ground cable issues do play hell on the electronics... Ummm... Do you have a fuel pressure gauge on the truck?

No, I don't have a fuel pressure gauge, but I'm gonna buy one shortly so I can keep a closer eye on the fuel delivery. It's next on the list even though I am in need of injectors. 193000 miles and haven't replaced them yet

Injectors??? The RV275 I got from CaJFlynn have over 400K miles on them and I'm still going... Slight miss now and then but still going strong at 20-21 MPG and good power.