Dreaded P0216 code, help/advice

[Tractorman]

Okay, that makes sense about what the guy from DAP told you regarding staying with OEM fuel line sizes from the tank to the lift pump.  

 

Just wanted to clarify that even though you will now have a 150 gph lift pump and a 1/2" line to the VP44, no more fuel will be flowing through the VP44 and returning to the fuel tank than when you had the lower gph lift pump.  The VP44's internal fixed displacement vane pump and the VP44's internal fuel routing determines how much fuel will return to the fuel tank.

 

- John

[Mopar1973Man]

11 hours ago, Tractorman said:

The VP44's internal fixed displacement vane pump and the VP44's internal fuel routing determines how much fuel will return to the fuel tank.

Typically 60% of the volume is returns as long and the pressure behind the overflow valve is above 14 PSI and then the fuel is return below that the value is close and nothing is returned. Being just quick math at 65 MPH and about 18 MPG which is a fair average your only injecting 3.61 GPH of fuel this means the remain volume is returned again only if the pressure is above 14 PSI behind the overflow valve. Stock lift pump (Carter) was only a 60 GPH pump at barely 13 to 14 PSI back when I fought with them during the Campaign phase which failed...

[JAG1]

Raptor 150 from Vulcan Performance was 420 bucks 4 years ago. That included (all new 1/2'' lines) and new draw straw with frame mount bracket and fuel gauge orifice. Also had the wire harness to run off the battery triggered by the ECM. Frame mount is easier to do.

[Mopar1973Man]

Just now, JAG1 said:

Also had the wire harness to run off the battery triggered by the ECM.

 

Assuming its a power relay setup and not a direct plugin to the ECM.

[JAG1]

That is correct. Based on what we know today running off the ECM for power is a slow process in which kills the ECM. This based on information we have often seen in the past and Michael Nelson having concluded that was the issue.

[Doubletrouble]

 Correct. I will be doing the relay mod when I install the new pump. I am certain the 150 Raptor pulls more amps than the oem Carter did so to protect the ecm I will be doing @IBMobile'IBMobile's fuel pump relay setup. 

 I will also order the relocation kit with the 1/2" line and a draw straw to be installed as soon as it warms up a bit. I talked to someone at @dieselautopower to see if that pump would be ok drawing through the oem fuel lines for a short time while waiting for warmer weather. They said it should be fine. This is to get the truck back on the road for now and also to see if the vp will be ok for a bit. I'm sure there was wear or damage to the timing piston during the LP failure.  Just would like it to last me about 3-6 months so I can replace it. Also a fuel pressure gauge is in the works as well.

[Tractorman]

 

13 hours ago, Mopar1973Man said:

Typically 60% of the volume is returns as long and the pressure behind the overflow valve is above 14 PSI and then the fuel is return below that the value is close and nothing is returned.

 

Under Fuel Injection Pump Description, The FSM states, "A greater quantity of fuel is required for cooling the VP44 than what is necessary for engine operation. Because of this, approximately 70 percent of fuel entering the pump is returned to the fuel tank through the overflow valve and fuel return line." 

 

So, your 60% is close enough, but you mention, "as long and the pressure behind the overflow valve is above 14 PSI and then the fuel is return below that the value is close and nothing is returned."  Why do you mention this?  Any time the engine is at idle or being fueled above idle, there is ALWAYS plenty of fuel flowing over the 14 psi overflow volve.  This flow is provided by the internal fixed displacement vane pump - not the lift pump.  So, return fuel flow is always happening - regardless of lift pump pressure.  An idling engine returns about 18 gph to the fuel tank.  As engine rpm's are increased, the volume of fuel retuning to the fuel tank will also increase because of the increased revolutions of the VP44's internal fixed displacement vane pump.

 

13 hours ago, Mopar1973Man said:

Being just quick math at 65 MPH and about 18 MPG which is a fair average your only injecting 3.61 GPH of fuel this means the remain volume is returned again only if the pressure is above 14 PSI behind the overflow valve.

 

I am fine with your math here, but again you mention, "this means the remain volume is returned again only if the pressure is above 14 PSI behind the overflow valve."  I ask again, why do you mention this?  The internal vane pump will ALWAYS be flowing plenty of fuel over the 14 psi overflow valve under this condition - even if the lift pump pressure is only 10 psi, for example.

 

I can understand people wanting higher volume lift pumps for high volume injectors that would be operated near their maximum flow at high engine rpm's, but the majority of the people who own these trucks do not operate their engine in this manner, including @Doubletrouble.  He basically has a stock setup.

 

On 1/19/2022 at 12:52 PM, Doubletrouble said:

A 150gph pump moves alot of fuel, that's 10 quarts or 2.5 gallons a minute. There is no way or engines use all this as we already know. The remainder is cycled through as a cooling liquid for the VP. Here's the issue. We run 1/2" line to carry this fuel, the return line is what? 5/16 coming out if the VP? There is a restriction. Which doesn't allow the fuel (150gph) to move fast enough which would create a bit of a jam at the pump impeller which in turn could be the creator of the cavitation. Based on the idea that an impeller in fluid that isn't moving at the same or similar speed as the impeller would cause turbulence and induce a cavitation effect.

 

 This is just my theory,  I hope I explained it in a way that it makes sense.

 

I'm a little late here, but since you mentioned that you are on a budget, a 100 gph lift pump would have easily accommodated your fuel needs for your application.  A stock VP44 fuel system will consume a maximum of well under 50 gph under the most demanding conditions.  This includes returned fuel from the VP44 and fuel burned by the injectors.  This is why the OEM lift pumps were rated at about 60 gph.  Remember, the lift pump only ensures that there is a positive pressure at all times at the VP44 inlet which is also the inlet of the VP44's internal fixed displacement vane pump.  It is only this internal vane that supplies fuel to all of the internal components of the VP44, including the fuel flow over the 14 psi overflow valve that returns fuel to the fuel tank.  The lift pump is there only to ensure that fuel is readily available at the VP44 inlet under all adverse driving conditions - such as pulling a heavy load up a long steep grade with an almost empty fuel tank.

 

You said, " Here's the issue. We run 1/2" line to carry this fuel, the return line is what? 5/16 coming out if the VP? There is a restriction. Which doesn't allow the fuel (150gph) to move fast enough"    You are sort of on the right track here.  The 5/16" return line leaving the VP44 is not a restriction.  The VP44's internal vane pump is a fixed displacement pump driven by the engine's camshaft.  This means the volume of fuel from this vane pump is determined by engine rpm only.  Nothing else.  This vane pump is the restriction in the VP44 - the VP44's fuel return lines are not the restriction.  The lift pump cannot push more fuel through the vane than the vane pump can displace, under any circumstances.  This is why the lift pump has to return so much fuel back to its suction side. 

 

As an example, if your engine was using near maximum horsepower and the VP44 was returning 30 gph and the injectors were using 8 gph, this would mean that your lift pump would be delivering 38 gph to the VP44. If the lift pump was displacing 138 gph at a specific psi at this moment, then the lift pump would be returning 100 gph to its suction side.

 

As a side note, I am going to say that your lift pump would not be cavitating.  The pump would be delivering 138 gph - 38 gph to the VP44 and 100 gph back to its suction side.   38 gph would be drawn from the fuel tank accompanied with the 100 gph being returned from the lift pump outlet, so there would be 138 gph always passing through the lift impeller.

 

I stand behind what I say here using my own truck as an example.  My OEM VP44 failed (0216 code) and was replaced at 87,000 miles in 2005.  Back then, the lift pump was always blamed.  I strapped a fuel gauge to my windshield and drove back and forth to work for five days for a total of 250 miles.  The lift pump easily stayed within specs for the whole duration.  Under warranty the VP44 was replaced with a remanufactured unit and the OEM lift pump was removed and an in-tank lift pump was installed.  I checked the new lift pump pressure, and it was far lower than the OEM lift pump.  The new lift pump was 6 psi at idle and 3 psi at wide open throttle.  I really didn't care because there was still a positve pressure at the VP44 inlet.

 

What wasn't known back then was that the VP44 had serious issues with material quality - timing pistons and bores made with poor material, an under designed rubber diaphragm to absorb pressure spikes, rotors that weren't deburred and would seize, poor soldered joints in the processor piggy backed onto the pump - just to mention a few.  The professionally remanufactured VP44 pumps addressed these concerns and now the VP44 is much more reliable. 

 

So, fast forward a few years and the replaced VP44 now has logged over 270,000 miles and is still running strong.  I ran the in-tank lift pump for just over 160,000 miles.  I removed it and installed a used FASS DRP-02 (about 65 gph) on the frame rail.  It operates at 12 psi at idle and 6 psi at wide open throttle.  That pump is still on the truck and has logged over 110,00 miles.

 

So, my point here is that the remanufactured VP44 on my truck has never seen over 12 psi and most of the time is running under 10 psi; however, the life of the VP44 does not seem to have been impacted.  This is also with a Smarty S03 tuner on a mild tune with RV275 injectors for the last 110,000 miles and 60,000 miles respectively.

 

@Doubletrouble, you ask a lot of good questions.  

 

Last summer I took things one step further.  A friand and I carefully measured return flow from the VP44 by letting the return fuel flow into a measuring container.  I also rigged a fuel bypass around the lift pump with a one-way check valve allowing flow to the VP44 when I disabled the electrical connection to the lift pump.

 

Results:

 

Lift pump operating:

Test #1:  engine at idle - .5 gallons pumped in 92 seconds

Test #2:  engine at idle - .5 gallons pumped in 94 seconds

Average fuel pumped is .5 gallons in 93 seconds = .3225 gpm rounded to .32 gpm or 19.35 gph

 

Lift pump disabled and bypassed

Test #3:  engine at idle - .5 gallons pumped in 93 seconds

Test #4:  engine at idle - .5 gallons pumped in 95 seconds

Average fuel pumped is .5 gallons in 94 seconds = .3191 gpm rounded to .32 gpm or 19.35 gph

 

These results clearly show that the lift pump has very little to do with how much return fuel flows from the VP44.

 

I performed one other test.  Since I am convinced that it is the internal vane pump that does all of the work, I disabled the lift pump and drove my truck to town and back – a 25 mile round trip - using the lift pump bypass circuit, so the VP44's internal vane pump was drawing fuel from the tank around the lift pump.  I drove the truck hard.  I accelerated and held 30 psi boost several times. I restarted the truck several times while running errands.  The engine never stumbled and continued to deliver the power it always does.  It ran as I expected it would.

 

- John

 

I will probably be editing as I will likely find mistakes in this post....

Edited January 30, 2022 by Tractorman

[Doubletrouble]

 That was a very risky test @Tractorman, I appreciate all this info, very interesting. 

 I went ahead and ordered the Raptor 150 as you saw earlier in the thread. I based this on increased potential volume and someone else had stated that a Raptor 100 they had showed signs of pressure drop over a period if time. 

 I will be doing some light mods in the future so planning ahead a little as well but the information you provided does provoke some interesting thoughts.

 Now in my case, I discovered after the fact that the lift pump failed. It did make it a couple miles to work afterwards so the vp was drawing fuel to some extent. It did not want to run well at all save for maybe at idle. Seemed like once the fuel pedal was pressed it didn't take long for it to starve for fuel, or so it seemed. 

 My hope is that the vp isn't completely toast yet but with your description above comparing that to my situation it sounds like it already fried. Which very well could be the case but, the vp on my truck does appear to possibly be a reman. Judging strictly on the external appearance. The aluminum has a newer, refreshed look to it if that makes sense. That alone is what gives me a slight bit of hope that it may last a little while in order to save the money to get a new reman from a good company.

 I'm sure there will be other weighing in on your comments above. This conversation could get interesting. There was also another member here that had rigged a bypass for a lift pump as an emergency fix I belive. Just don't remember who it was.

 We shall see where this goes. Thanks for all the info tractorman. 👍 

[wil440]

I tested my truck.

mechanical lift pump, idles at 8 psi ish  wot around 22 psi ish   always a lot of fuel returning to tank even at 8, I didn't measure it like John as I was happy with what I saw, fuel temps never a concern for me

[Mopar1973Man]

Just depends on if your pumping from the tank or the return fuel in the sender. The return fuel is going to be hotter. I pump from inside the tank, not out of the sender basket. 

[Doubletrouble]

1 minute ago, Mopar1973Man said:

Just depends on if your pumping from the tank or the return fuel in the sender. The return fuel is going to be hotter. I pump from inside the tank, not out of the sender basket. 

 Once I install the 1/2" line there will be a draw straw to pull from in the tank away from the sending unit basket.

 When installing the draw straw, is there an optimum place to put it?

[Mopar1973Man]

If you want ot reduce the 1/4 tank issue.

 

Rearward is best for launching hard or center for most common driving. The last straw I installed actually suggest by AirDog to cross drill the straw at the bottom location and then cut it off so its touching the bottom. I changed it slightly and measure and cut it to touch the bottom and then notched it like what mine is with a cutoff wheel. Nothing hard but pulling from the true bottom. 

[Doubletrouble]

I believe I saw pics of how you notched one when installed. I was going to go that rout myself. 

 I don't really do any hard laughing, normal driving and occasionally towing a fifth wheel camper or utility trailers. Sounds like a central location away from the basket would be best for my situation. 

[Tractorman]

6 hours ago, Doubletrouble said:

That was a very risky test @Tractorman, I appreciate all this info, very interesting. 

 

I would have never done this test back in 2005 when my OEM VP44 failed.  I didn't know anything about the VP44 system back then.  But, with what I have learned since, I am confident the risk was very low or even non-existent.  I did not figure this out by myself.  I have read detailed posts from forums where people had done extensive VP44 return flow volume tests with a flowmeter under all kinds of driving conditions with different lift pumps pressures.  All testing results concluded that fuel volume returning to the tank from the VP44 never changed under specific driving condition regardless of lift pump pressure, even when the lift pump pressure was pulled down to zero psi.  During the testing, engine performance never faltered, even under heavy loads.  These tests were done as early as 2001, so there were some people who were clearly not satisfied with some of the myths associated with the VP44 fuel system.  I, for one, am very happy that these people went to great extents to help us better understand the VP44 fuel system.

 

After my testing, I left the lift pump bypass circuit in place.  If I ever have a lift pump stop working on a road trip, fuel will still be drawn into the VP44 by the internal vane pump.  The fuel will simply flow around the dead lift pump.   My low fuel pressure light on the dash will illuminate, but my truck will still be able to be driven home without harming the VP44 injection pump.  Without the lift pump bypass, the non-working lift pump could cause a significant restriction that could harm the VP44 and could also require that truck be towed.

  

There are many, many applications where a lift pump is not even used with VP44 fuel injection systems - fuel is just gravity fed from a fuel tank.  Typically, the VP44 fuel systems that do not use a lift pump are in a very stable environment, so the lift pumps are not necessary. 

 

We need to have lift pumps on our engines, otherwise we would have a less reliable fuel system.  A couple of good examples would be: 

 

     *  After a fuel filter change it could be very difficult to start the engine without a lift pump, especially if the fuel filter wasn't prefilled.  Bleeding air from the injectors would probably be a necessity and could take a long time.  A lift pump that can be cycled for 20 seconds at a time (without the engine running) will slowly purge air the through the small hole on the upstream side on the 14 psi overflow valve.  Consequently, the engine will start easily.

  

     *  Just the smallest air leaking into the fuel system could and would cause roadside breakdowns.  Just imagine going to the store and your truck won't start when you are ready to leave because there is a little air in the fuel system.  There you would be with the hood raised trying to bleed injectors without the aid of a lift pump - the truck may have to be towed.  With a lift pump in the fuel system, you might notice a stumble on start up when leaving the store, but you truck would not be disabled.  You would be able to get the truck home to diagnose the problem. 

 

I apologize for the long posts, but I really want people to have the best possible chance to understand the VP44 fuel system to help make sound decisions regarding the fuel system on their trucks.

 

- John

 

 

[Andyba20]

This is really interesting @Tractorman. So does this change the long held gospel of 14psi fuel pressure or more at all times? Thanks for taking the time to research and test this. 

[Tractorman]

49 minutes ago, Andyba20 said:

So does this change the long held gospel of 14psi fuel pressure or more at all times?

 

Yes, I am afraid it does.  Hopefully, people who read this thread will be prompted to ask questions about the complete operation of the VP44 system and not just be focused on one item, that item being lift pump pressure.  

 

I have researched the VP44 injection pump operation for years and I wanted to get some miles on my own remanufactured VP44 that has never seen lift pump pressures any higher than 12 psi before I began posting this information.   I am grateful for the 270,000 plus miles this VP44 has provided me, and I know that it could fail at any time.  When it does fail, I will not be disappointed - it has given me great performance for a long life.  Also worth noting is that all of the fuel lines and fuel filter housing are OEM stock on my truck.  The only fuel line modification that has been done is the fuel return line that carries the VP44 return fuel and the return fuel from the head is now routed to the fuel tank filler neck.

 

I really appreciate your comments.

 

- John

[Andyba20]

That’s the beauty of this forum. New information is brought to light, and things evolve. This one seems to be a game changer for sure. 

[JAG1]

1 hour ago, Tractorman said:

 

Yes, I am afraid it does.  Hopefully, people who read this thread will be prompted to ask questions about the complete operation of the VP44 system and not just be focused on one item, that item being lift pump pressure.  

 

I have researched the VP44 injection pump operation for years and I wanted to get some miles on my own remanufactured VP44 that has never seen lift pump pressures any higher than 12 psi before I began posting this information.   I am grateful for the 270,000 plus miles this VP44 has provided me, and I know that it could fail at any time.  When it does fail, I will not be disappointed - it has given me great performance for a long life.  Also worth noting is that all of the fuel lines and fuel filter housing are OEM stock on my truck.  The only fuel line modification that has been done is the fuel return line that carries the VP44 return fuel and the return fuel from the head is now routed to the fuel tank filler neck.

 

I really appreciate your comments.

 

- John

Now because of this contrarian view about fuel pressure, out of spite I 'm going to watch my return flow either increase or stay the same while I move the seat forward with a stick on the go pedal. Just to see what happens if anything as I can look down my fill neck and see the flow. Never thought to do this before.

Edited January 31, 2022 by JAG1

[Tractorman]

Looking forward to hearing the results.

 

- John

[wil440]

16 hours ago, Mopar1973Man said:

Just depends on if your pumping from the tank or the return fuel in the sender. The return fuel is going to be hotter. I pump from inside the tank, not out of the sender basket. 

I pump out of the basket and the return is also in the basket, I have made a filler neck return last summer but never got around to fitting it

My truck NEVER goes below 1/2 tank

Idle FP is 8 ish . 2k plus is 22 ish

Mechanical LP is just about in cold air flow from the front

Fuel temps low

 

I did some testing like I said earlier but not with a flow gauge, I have a mechanical FP gauge and with engine idling and FP around 8psi I used a brake line clamp on my return line from the FP regulator to tank and very slowly restricted it and saw a comparative increase in FP with every turn of the screw, I only went to a point where I was happy 

This proved to me that while at idle I "only" have 8 psi what I do have is a lot of fuel going back to tank and with a mechanical LP it only goes up with RPM