I am planning the do a cooling system maintenance on my 1998.5 and have not been able to find the correct thermostat for it . The ones that I have been handed are the large one for the 12 valve. I did try one about 7 years ago and had such wild swings in temp that I thought I had done something wrong. After much thought and trouble shooting I found that the thermostat did not look like what I removed ( my fault I did not compare them when I removed the old one). I went back with the old one and finally found one that matched. Here I am 7 years later and the only one that I can find is for the 12 valve and in their data base it said that that is the only one fits from 89 to 09 which I know is wrong.The stant pn 14289 or 46289 for the heavyduty but I could not contact anyone at stant but I did contact a gates tech support and he said that stant makes theirs but he has not got back to me yet. The picture shows the difference with the one on the left is the correct one. I have been to every place I can think to find one including cummins dealers  within a 100 mile raduis and they all pull the 12 valve one. How are the rest of you finding yours. I even ordered one from Rockauto that had the correct picture but when it showed up it was the 12 valve.

7 hours ago, Mopar1973Man said:

Most likely picking up hot return fuel from the sender?

Mine picks up from the sender but I don't have a hot fuel problem.... far from it

Neither do I. typically below 130*F even with 100*F weather.

 

@wil440if I recall your return goes back to the sender, correct? Besides the very obvious, one difference between your lift pump and mine is that my relief valve dumps the extra fuel directly back into the suction side of the pump, not back to the tank. So, it basically gets churned and hot like the water from a water-brake dynamometer, unlocked torque converter, etc., until it gets its turn to go down the line and either get burned or sent through the head to presumably pick up even more heat.

 

I do wonder I shimmed the internal relief to a higher pressure and then installed a downstream external regulator back to the tank what the change in fuel temp would be since it would not get churned over and over.

One of few points I like about AirDog. Not churned over and over. Every pass its filtered more each time it returns to the tank. Unlike stock or Raptor pumps they do churn the fuel over and over and cause cavitation.

9 hours ago, LorenS said:

@wil440if I recall your return goes back to the sender, correct? Besides the very obvious, one difference between your lift pump and mine is that my relief valve dumps the extra fuel directly back into the suction side of the pump, not back to the tank. So, it basically gets churned and hot like the water from a water-brake dynamometer, unlocked torque converter, etc., until it gets its turn to go down the line and either get burned or sent through the head to presumably pick up even more heat.

 

I do wonder I shimmed the internal relief to a higher pressure and then installed a downstream external regulator back to the tank what the change in fuel temp would be since it would not get churned over and over.

Yes my return goes back to the sender.  I have a return to the neck all made up but no need to fit it.

I also don't get hung up on pressure,  6psi at idle but 20psi at anything over 2k, at idle even at 6psi the return line on my truck is sending a lot of fuel back to tank 

You could do as you suggest but might be too much for your pump in the long term 

@LorenS, I've been thinking of doing the same thing. I don't know my actual fuel Temps but with the pump I have its bypassing a lot more fuel than I'm using. 

 Thinking about an inline regulator that dumps back to the tank. Maybe run the excess through a small filter? I don't know. Still pondering it 

1 hour ago, Doubletrouble said:

Maybe run the excess through a small filter?

No not on a return line from the regulator being if the filter plugs up then the pressure will rise. This is why a AirDog is the blow off of the regulator heading to the tank. The best part the filter is a AHEAD of the regulator and all fuel is filtered before returning. 

 Gotcha @Mopar1973Man, makes perfect sense. 

22 minutes ago, Doubletrouble said:

 Gotcha @Mopar1973Man, makes perfect sense. 

 

Gotcha covered...

 

Yes I've torn apart a few AirDog's and Raptor's and even Carter stock lift pumps to see how they work. The Raptors are hung up on the returning to the inlet of the pump so the fuel starts to cavitation and then sends the bubbles through the pump so that why the pressure stability issues with non-returning pumps. The Raptors also have issues with the adjustable regulators the springs tend to hang up and stick which doesn't help either.   

 I've been considering putting on an external regulator and just run the Raptor wide open. Have the external regulator return to the tank. This will all take place in the midst of moving the lift pump to the frame to be closer to the tank as well. That'll leave more room for another filter if needed.

This was the big problem with the Raptors people learn later on about what they missed with buying a Raptor. Now they try to reinvent the pump and get a return line and external regulator. The only thing you'll miss is the air separation which is a straw that goes to the bottom of the filter so the air floats to the top and sent out on the return line. Now doing custom installs like the last one I did I love when I ditch the instructions and do it my own way it turns out much better. That white Dodge the owner was super impressed with the setup and how the lines all go inside the frame and protected from debris strikes. Yeah I'm going to build a filter cover when the truck comes back after my road trip to Pigeon Forge, TN.

 

 I shyed away from the full airdaog setup mainly because of price. That was alot of money to part with once the truck surprises you with a failed lift pump. Wasn't ready to spend that kinda coin 

Look at it this way I bought 3 stock fuel pumps for 250 a piece in 9 months (Carter campaign lift pumps from Cummins). I next bought the AirDog in 2006 for 600 dollars and never spent another penny. OE pump lasted 250k miles. Replace with a bad 3rd Gen AirDog and seals failed about 3k miles. AirDog upgraded me to the 4th Gen 165 GPH pump. No problems since. 

So the Raptor 4G 150 churns the fuel at the pump? 

1 minute ago, Threadzy said:

So the Raptor 4G 150 churns the fuel at the pump? 

Yes sir. No 3rd return line to the tank.

56 minutes ago, Mopar1973Man said:

Yes sir. No 3rd return line to the tank.

So no fuel passes through the relief valve at the VP back to the tank? 

Doesn't matter. It's a restricted flow if you pull the banjo out and look at the port in the VP44 it small. No 150 GPH your only using 2.5 GPH at 55 MPH at 20 MPG in the VP44 injected. So the other 147.5 GPH is routed from the outlet of the Raptor back to the inlet, churning the fuel and creating cavitation. This is roughly speaking not counting limited VP44 return.

 

 

 

Return hole size.

 

Inlet size

So, it would probably be better for the pump itself and to eliminate the cavitation by running a 3 leg regulator? I know it would probably be better to just start with a all inclusive airdog (money permitting)  but for those of us that did not.

@Mopar1973Man So even though my fuel pressure gauge is showing 15 psi no fuel is coming back from the return? Sorry if I’m be redundant.  I put the return line into my filler neck thinking I was doing something good.   I actually never looked down the neck to confirm any return flow. 

 At 15psi between the filter and vp44 you will still get return fuel through the vp44 like you would normally.

 @Mopar1973Man was saying that the Raptor type pump (mine is the 150) will regulate the pressure by rerouting the excess fuel above 15psi back through the head of the pump.