It is definately when the truck is hot so the diaphragm sounds like a much better problem then a fried pump even though both still bad.
Sometimes the pump will not kick on when I turn the key to on and the WAIT TO START does not come on. So i "Reset" it and turn the key off and then back on and it kicks on and the truck starts much easier.
Do you have a diagram or a more detailed description of how to hook it to an oil pressure switch?
Or might I be better off just buying a new aftermarket lift pump and give the injection pump some more reassurance?
I know the truck has 200,000 miles and **** does wear and tear but its a real bummer when you just bought the truck and all the problems start 2 days after you buy it

 

Well, if the metering diaphragm has been damaged, then adding a lift pump will make the problem harder or more persistent. That is not trying to steer you away from a better lift pump by any means, just letting you know. The higher pressure from even a new stock pump can over ride the metering diaphragm causing the hard start when hot condition. It is really key that you check, that the problem goes away with the lift pump circuit disconnected, to isolate that the diaphragm is indeed the issue. Do that before spending any money on the oil pressure switch set up.

If that is indeed the problem, then proceed to the oil pressure switch as the solution. I have always used hobbs adjustable 4-15psi N/O switches with a 1/8th npt thread on them. If you use the port on the top of the oil filter housing, it will work perfectly. An aftermarket lift pump will come with a relay, if you wire this switch into either the power or ground wire of the relay trigger, the circuit won't be complete until the switch is in the closed position and the lift pump will then turn on.
Sean

 

Well after I posted that I got to thinking
Since my truck has a FASS 150 system, the lift pump is bypassed.
So my guess is the VP44 is junk...BIG surprise
But I also need to trace the wiring on the FASS system and double check that he has it wired right because sometimes I have turned on the key and not heard the pump but turning the key off and then back on kicks the pump on
Is this a sign of the Fass pump going out also or more possibly just bad wiring

Does anyone wanna cut me a killer deal on a VP44? haha

 

p-pump it

 

Haha I'd love to P-Pump it, If you wanna sponsor me and pay for it I'm all for it haha
What's it cost these days to P-Pump a 24v

 

not sure on the cost and as for a sponsor my wife is mine!!!!!!! Just send out a quote p-pumper is the way to go easy to work on and lots cheaper but you can tune on the fly.

---AutoMerged DoublePost---

Talk to luke at diesel dawgs he is on here and they have a vp kit pretty cheap!!!!

 

i put the 150 air dog on my truck and now sometimes it takes forever and three days to start it usually after u drive it and try and restart within a hr or so any idea what the problem could be? thanks