Hey everyone, new paying member here, having issues with my truck and looking for some guidance. My truck is an 01 24v HO. I have had zero drivability issues since purchasing it about seven years ago until yesterday. Driving down the road as per normal when the engine just suddenly shuts off. I coasted it to the side of the road noticing the check engine light was on so immediatley cycled the key to view codes. I was met with P0230, P1688 and P1689. Luckily I was semi close to my shop so had some good Samaritans help me push it the rest of the way there. The truck is a crank but no fire scenario. I first turned the key on and confirmed the lift pump started and primed. I then bumped the key to allow the lift pump to run and opened the schrader on the injection pump inlet. Fuel was present and spraying out as I have always seen when bleeding after a new filter install. I then started checking the lift pump and injection pump circuits with some strange results. Pin 2, component side of lift pump to ground showed open limit on my ohm meter. Pin 2, harness side of lift pump showed the same result. Spent some time messing with that to make sure I was getting good connection to the block when testing, no change in results. In frustration I moved on to the injection pump. Confirmed voltage on injection pump connector of 12.5 volts. Removed ECM connector and resistance tested pin 13 (Datalink +) to the ground pin on injection pump connector aswell as battery ground. Both results from this were also open limit on my ohm meter.... At this point I was starting to doubt my meter, checked resistance from injection pump connector ground to battery negative, .6 ohms so meter was functioning. Am I looking at a severed harness? Where should I go from here? I am just assuming the meter saying open limit on all of these circuits would mean the wires are damaged / broken. It seems unlikely to me that they would all fail at the same time but I guess stranger things have happened.

 

Hopefully all of the wisdom here can help me figure this out!

The fuel suction line sometimes cracks or gets rusty right at the point where it enters the top of the tank. PIA to get to it.

@Great work! Thanks for that, to save people from reading back in the thread I will ad that I installed an airdog raptor 150gph kit in the truck. That included 1/2" fuel line upgrade aswell as a 1/2" draw straw upgrade so everything from draw straw to the filter housing is brand new. I also pulled my box on my truck and went through it all after this incident and found no issues, airleaks, or blockages.

12 hours ago, Basranabread said:

I did end up purchasing the 150gph pump.

 

Does this lift pump  have a dedicated return line to the fuel tank?  Or, does the fuel get returned internally to its own suction?  Is the lift pump OEM mounted, or frame rail mounted?

 

Example of fuel flow with an idling engine:  VP44 returns 18.5 gph to fuel tank and injectors consume .5 gph.  Lift pump will be flowing 18.5 gph to VP44.  I am going to round that number up to 20 gph.  The 150 gph lift probably does not produce 150 gph as pressure rises, but I am going to assume that it does just for purpose of discussion.  So, an idling engine would produce the following lift pump results:

 

*  150 gph lift pump with dedicated return line -       20 gph from pump to VP44, 150 gph from tank to lift pump inlet, 130 gph returning to tank

*  150 gph lift pump without dedicated return line -  20 gph from pump to VP44,   20 gph from tank to lift pump inlet, 130 gph returning to suction side of lift pump (within the lift pump housing).

 

Two completely different behaviors.  Note that with a dedicated fuel return line, you will see a maximum flow only from the fuel tank to the inlet of lift pump, consequently a large suction line is required. 

 

You are experiencing one of the drawbacks to using only a pressure gauge for troubleshooting.  You need to see the flow! (Or, lack of it).  And, you need to see the pressure and flow at the inlet of the VP44 (not sure where your gauge is plumbed).

 

Your symptoms while driving strongly indicate a disruption of fuel flow.  I recommend that you temporarily extend the fuel line that is connected at the VP44 and direct that fuel line into a five gallon bucket.  Run the lift pump without starting the engine.  You should be filling the bucket with a continuous fuel stream at the approximate rate of 150 gph.  That would be 2.5 gpm.  It will be obvious whether or not the lift pump is performing up to specs. 

 

As far as your condition of observing fuel pressure at 0 psi and hearing noise - it will probably mean only one the following:

 

*  cavitation - a very restrictive blockage in lines / fittings between the fuel tank and inlet of lift pump (very likely a problem)

*  entrained air - lots air being drawn in lines / fittings between the fuel tank and inlet of lift pump (not likely a problem - you would likely see fuel pressure, but  with an erratic needle)

*  lift pump regulator ball chattering - usually accompanied with fuel pressure and an erratic needle.

 

 

- John

 

 

 

 

30 minutes ago, Tractorman said:

 

Does this lift pump have a dedicated return line to the fuel tank? Or, does the fuel get returned internally to its own suction? Is the lift pump OEM mounted, or frame rail mounted?

 

This lift pump uses the factory return line to the tank and is a frame mounted pump.

 

47 minutes ago, Tractorman said:

 

 

47 minutes ago, Tractorman said:

 Your symptoms while driving strongly indicate a disruption of fuel flow.  I recommend that you temporarily extend the fuel line that is connected at the VP44 and direct that fuel line into a five gallon bucket.  Run the lift pump without starting the engine.  You should be filling the bucket with a continuous fuel stream at the approximate rate of 150 gph.  That would be 2.5 gpm.  It will be obvious whether or not the lift pump is performing up to specs. 

 

I agree completely that it is was fuel starvation and am starting to think that it was cause by the loose pressure regulator. I am going to perform this test today and report back.

 

39 minutes ago, Tractorman said:

As far as your condition of observing fuel pressure at 0 psi and hearing noise - it will probably mean only one the following:

 

*  cavitation - a very restrictive blockage in lines / fittings between the fuel tank and inlet of lift pump (very likely a problem)

*  entrained air - lots air being drawn in lines / fittings between the fuel tank and inlet of lift pump (not likely a problem - you would likely see fuel pressure, but  with an erratic needle)

*  lift pump regulator ball chattering - usually accompanied with fuel pressure and an erratic needle.

 

 I suspected the same as you are saying here. I did remove the box from my truck and go over everything from inside the tank to the suction of the pump and found no blockages or large airleaks. The only time it read 0 psi was prior to me discovering the regulator assembly was loose from the pump (assembly error from airdog) and leaking fuel out. The pump has been intermittently noisy ever since this discovery until I cracked the drain on the fuel bowl during diagnosis. Which puzzles me.

22 minutes ago, Basranabread said:

This lift pump uses the factory return line to the tank and is a frame mounted pump

 

So, you saying that there is a dedicated fuel return line?  To my knowledge, OEM lift pumps do not use a dedicated fuel return line.  Maybe I am missing something here.

 

- John

15 minutes ago, Tractorman said:

 

So, you saying that there is a dedicated fuel return line?  To my knowledge, OEM lift pumps do not use a dedicated fuel return line.  Maybe I am missing something here.

 

- John

 

As far as I am aware it uses the return line off of the vp44 which heads to the firewall and T's together with the injector return line and back to the top of the tank. It has a ball check pressure hold back in the banjo bolt that connects this line to the vp44.

36 minutes ago, Basranabread said:

This lift pump uses the factory return line to the tank and is a frame mounted pump.

Stock lift pumps do not have a return...

 

Only fuel system with a return is a AirDog 100/150/165 or a FASS 100/150/165 fuel system. Typically have two filters. Now like AirDog Raptor series does not have a return to the fuel tank. FASS DDRP does not have a retrun to the tank. There are few other pumps are just in and out without returns. 

 

Then no pump system out uses the stock return line because its too small for the volume. It only 6mm ID steel pipe or down on the frame would be a bit larger but nothing should be returning fuel in that line but the injector return and VP44 return that should be it. There should be zero pressure in the return line because that would cause pressure problems being the pressure will blow pass the overflow valve and back flood the VP44 screwing with the timing and other issues. Also restricting the cooling flow being its fighting to return to the tank as well. 

 

I would high suggest you remove that return from the pump and plumb it to the filler neck of the tank. 

19 minutes ago, Mopar1973Man said:

Stock lift pumps do not have a return...

 

Only fuel system with a return is a AirDog 100/150/165 or a FASS 100/150/165 fuel system. Typically have two filters. Now like AirDog Raptor series does not have a return to the fuel tank. FASS DDRP does not have a retrun to the tank. There are few other pumps are just in and out without returns. 

 

Then no pump system out uses the stock return line because its too small for the volume. It only 6mm ID steel pipe or down on the frame would be a bit larger but nothing should be returning fuel in that line but the injector return and VP44 return that should be it. There should be zero pressure in the return line because that would cause pressure problems being the pressure will blow pass the overflow valve and back flood the VP44 screwing with the timing and other issues. Also restricting the cooling flow being its fighting to return to the tank as well. 

 

I would high suggest you remove that return from the pump and plumb it to the filler neck of the tank. 

 

Okay so it's basically like 3 return circuits then. Pump returns internally to itself, vp44 return and injector return which share a line back to the tank. Learned something there. Since the pump internally returns, is it possible that this regulator being loose pulled in air and caused an airlock in the pump? Causing my noise / 0psi scenario and when I opened the fuel bowl drain it purged it which resulted in the pump sounding and acting as it should now?

Gotta ask do you have the new push lock style fitting or the old school JIC hydraulic screw fittings? If you have push lock style that just snaps it might be pulling air in. So a little temporary trick is to pull the suction line fitting as put a coating of thick bearing grease on the smooth nipple and re-install the fitting if this stops the air lock issue then I would suggest swapping to the old school JIC fittings and that would stop the air leak issue on the suction line. Why is this a problem simply the push lock style fittings will roll back the o-rings in the suction lines and loose there seal and leak air. 

 

This is best... Can be got from Vulcan Performance. Just Eric I sent you to him.

 

This is not good... These have the air leak issue.

 

1 hour ago, Mopar1973Man said:

Gotta ask do you have the new push lock style fitting or the old school JIC hydraulic screw fittings? If you have push lock style that just snaps it might be pulling air in. So a little temporary trick is to pull the suction line fitting as put a coating of thick bearing grease on the smooth nipple and re-install the fitting if this stops the air lock issue then I would suggest swapping to the old school JIC fittings and that would stop the air leak issue on the suction line. Why is this a problem simply the push lock style fittings will roll back the o-rings in the suction lines and loose there seal and leak air. 

 

This is best... Can be got from Vulcan Performance. Just Eric I sent you to him.

 

This is not good... These have the air leak issue.

 

Mine has the quick connect fittings. I just tested everything above and it was all good. Took the truck for a drive and was okay until I got into it hard again and did the same thing 0psi on the lift pump and hesitation like crazy. I have these push lock fittings at work so will attempt to replace them all and see what happens.

7 hours ago, Basranabread said:

Okay so it's basically like 3 return circuits then. Pump returns internally to itself, vp44 return and injector return which share a line back to the tank. Learned something there. Since the pump internally returns

I'm fairly certain every Airdog 150 does NOT return internally. And it should not utilize the cylinder head/VP44 return line as it is too small. The AD 150 (and similar) should have it's own dedicated return line - whether back to a connection on your draw straw or a tee on the filler neck hose. Do you have photos of your setup you can post?

 AirDog | R1SBU371 | Raptor Pump – Universal 150 GPH  does not need a return line (specifically stated in the information). 

 

10 hours ago, Tractorman said:

I recommend that you temporarily extend the fuel line that is connected at the VP44 and direct that fuel line into a five gallon bucket.  Run the lift pump without starting the engine.  You should be filling the bucket with a continuous fuel stream at the approximate rate of 150 gph.  That would be 2.5 gpm.  It will be obvious whether or not the lift pump is performing up to specs. 

 

9 hours ago, Basranabread said:

I am going to perform this test today and report back.

 

  Since we didn't receive a report of the results, I have to assume you didn't perform the test.  Personally, I would not be driving the truck without first performing this test.

 

- John

1 hour ago, Tractorman said:

 AirDog | R1SBU371 | Raptor Pump – Universal 150 GPH  does not need a return line (specifically stated in the information). 

 

 

 

  Since we didn't receive a report of the results, I have to assume you didn't perform the test.  Personally, I would not be driving the truck without first performing this test.

 

- John

Sorry @Tractorman, I mentioned in my response to mopar1973man that I had performed the tests prior to another test drive and all seemed well. I removed the discharge line from the filter housing and ran the pump. It produced approximately half of a 5 gallon pail in a minute which is about what it should do. I then took the truck for a test drive and the exact same thing happened. All was well until about 45min into the drive, I layed into it (low on power) then tried again with slight hesitation. Checked the pump gauge and it was 0psi again with a noisy pump. Pump again is now noisy and cavitating once again. I left the truck for the rest of the evening out of frustration but am going to perform this test again tomorrow with a now "angry" pump to see if the results are different.

On 2/10/2023 at 7:47 PM, Basranabread said:

I pulled over and jumped out to look at the gauge installed on the Raptor lift pump.

 

If my understanding is correct, you cannot monitor fuel pressure while driving.  Is this true?

 

If it is true, I highly recommend to temporarily plumb in a fuel pressure gauge that you can strap onto the driver side windshield wiper arm.  I did this once over 18 years ago when I was told my lift pump was failing.  I drove the truck back and forth to work for a week (logged over 250 miles). It turned out the lift pump was not failing at all.

 

Since your lift pump passed the bucket test with flying colors, it is possible there is some foreign matter moving around in the fuel tank.  When you start driving, that foreign matter may move into a position that temporarily blocks or partially blocks in-tank suction line.   When you return home and start messing with the pump, the foreign matter may just drop away and all seems well again.

 

- John

2 hours ago, Tractorman said:

 

If my understanding is correct, you cannot monitor fuel pressure while driving.  Is this true?

 

If it is true, I highly recommend to temporarily plumb in a fuel pressure gauge that you can strap onto the driver side windshield wiper arm.  I did this once over 18 years ago when I was told my lift pump was failing.  I drove the truck back and forth to work for a week (logged over 250 miles). It turned out the lift pump was not failing at all.

 

Since your lift pump passed the bucket test with flying colors, it is possible there is some foreign matter moving around in the fuel tank.  When you start driving, that foreign matter may move into a position that temporarily blocks or partially blocks in-tank suction line.   When you return home and start messing with the pump, the foreign matter may just drop away and all seems well again.

 

- John

You are correct and I had the exact same idea to rig up a gauge I can monitor on test drives, working on this today. 

 

Is it possible something is in the tank? I guess but I have had the fuel sending unit out twice during this process, shined a light in the tank to inspect while looking for restrictions. I even put my arm in the tank through the sending unit hole and swept around to see if I could feel anything as I could not see anything. 

 

My next step is I will attempt to replace the suction side quick connect fittings with hydraulic or whatever I can come up with today. I have a hydraulic hose shop at work so have a large access to fittings and adapters. 

 

The fact that the pump is still making cavitation noise after regaining pressure post losing it makes me suspect air ingress and with nothing obvious I'm hoping it is indeed these fittings.

I'm not familiar with that pump set up but is it possible the polarity is reversed and it's running backwards 

56 minutes ago, Great work! said:

is it possible the polarity is reversed and it's running backwards 

I've seen that happen on a fuel pump.  Customer replaced his fuel pump and couldn't get it started because he wired it backwards; reversed the two wires and it ran like a champ.    

3 hours ago, Great work! said:

I'm not familiar with that pump set up but is it possible the polarity is reversed and it's running backwards

 

Anything is possible I suppose.  But, he did run a flow test into a 5 gallon bucket.  One minute to fill the bucket half full = 2.5 gpm or 150 gph, which is what the pump is rated for.  I don't think those numbers could have been attained if the pump was running backwards.

 

- John

3 minutes ago, Tractorman said:

 

Anything is possible I suppose.  But, he did run a flow test into a 5 gallon bucket.  One minute to fill the bucket half full = 2.5 gpm or 150 gph, which is what the pump is rated for.  I don't think those numbers could have been attained if the pump was running backwards.

 

- John

I also don't believe that the pump would create any fuel flow towards the engine if it was running backwards? It's an internal gear or gearotor pump. As far as I know if you spin them backwards you outlet and inlet ports are then reversed. I could be wrong on this though as the internal return may complicate this scenario.

 

No luck on fittings for the in cab gauge or suction line today unfortunately. I will attempt again tomorrow and update if I can make anything happen.

I believe you are correct.

 

I was being a bit facetious in my previous reply.

 

- John