SO...after 15 years, my fuel pressure sensor is dying. Called EDGE and they suggested a replacement sensor: 4000700 for $90. Not being able to 100% sure tell me it would work with the Attitude... Any suggestions on this? alternate sensors, alternate fuel pressure/EGT gauges? I am down to only using the Attitude to monitor these two things and would seriously consider changing to a 2 in one guage.... the JUICE module is apparently dead.

Unless you are absolutely set on having a gauge readout, there is the option of using just using a low pressure warning light. I have used the adjustable LEFOO LF20 pressure switch for years. It is my personal choice because the only thing that matters is that there is always positive fuel pressure at the VP44 inlet. The actual pressure value is unimportant. The activation of a LED warning light will catch your eye more readily than a low reading of a fuel pressure gauge.

This particular pressure switch has a range of 0.5-150 psi and comes preset at 10 psi. It is compatible with oils and diesel fuels and it is very easy to adjust to a custom pressure value. The cost is under $40 from a variety of sources, including Amazon. You can easily wire in a LED light at a location of your choice.

• John

IF I can customize the pressure alert, I would be fine with an alert bulb... I want to know my lift pump drops below 14 psi... I'd still have to have some way to check the pressure when setting it.

5 hours ago, Tim Waldo said:

I want to know my lift pump drops below 14 psi..

Any particular reason you don't want your lift pump to fall below 14 psi?

5 hours ago, Tim Waldo said:

I'd still have to have some way to check the pressure when setting it.

You could plumb in a tee right at the injection pump fitting just for your test gauge.

• John

Edited yesterday at 02:22 AM1 day by Tractorman

the over supply valve/over pressure valve or whatever you call it pops off at 14 psi... at 14 psi you get extra fuel flow to cool the pump.... at least that is what I've read and why my new VP44 came with a NEW OPValve... with specific instructions that it HAD to be installed or the pump would not be warrantied.

The fuel pressure below 14 PSI is lower return flow while the engine is running. Basically demand of the engine will take more fuel to the engine and less on the return from the VP44 pump. If fuel pressure is not stable then your demand volume is greater than your supply volume. Return volume is what remains after injection cycle occurs. This why is not suggested to below 14 PSI because the overflow valve is closed by 10 PSI and no return flow occurs.

Edited yesterday at 03:30 PM1 day by Mopar1973Man

so my statement albeit in the right intent was technically incorrect?

So would I be safe just knowing my fuel pressure dropped below 10 psi?

Typically my fuel pressure runs between 13 and 16 psi... with a working guage.

ISSPro EV3 gauges give both functions electronic gauge with Bluetooth ability to reprogram any settings in the gauge. Lights (color), warning color lights, set range of warning, much more. Might take a look at those.

2 hours ago, Tim Waldo said:

the over supply valve/over pressure valve or whatever you call it pops off at 14 psi... at 14 psi you get extra fuel flow to cool the pump.... at least that is what I've read

It is true that the overflow valve is regulated at 14 psi. However, this pressure (and the fuel return flow provided) has no correlation to lift pump pressure.

1 hour ago, Mopar1973Man said:

This why is not suggested to below 14 PSI because the overflow valve is closed by 10 PSI and no return flow occurs.

Your statement here is misleading. I do agree that the overflow valve will be closed when fuel pressure that the overflow valve senses falls below 14 psi.

However, the fuel pressure that the overflow valve senses is provided from the flow of the VP44's internal fixed displacement vane pump, not the lift pump. Consequently, the volume of return fuel through the overflow valve is the same for a given engine rpm and load whether lift pump pressure is 5 psi or 20 psi.

The VP44's internal fixed displacement vane pump's flow is regulated to well above 100 psi. This is why the 14 psi overflow valve opens immediately when the engine is started. It never closes until the engine is shut off - regardless of lift pump pressure.

Since the lift pump and the VP44's internal fixed displacement vane pump are plumbed in a series circuit, the volume of the the internal vane pump cannot be changed by lift pump pressure. The volume can only be changed by changing engine rpm.

In the past I have posted the results of extensive testing by others (using a flow meter in the fuel return circuit) that clearly supports what I am saying here. This testing was performed in April of 2001 (before any of us even owned our trucks) by a few Turbo Diesel Register members. About three years ago I performed similar tests, as well. The results showed that fuel return flow remained the same, even when the lift pump was turned off and bypassed.

I post this information in hoping to give a better understanding of the relationship between the lift pump, the internal vane pump, and the overflow valve operation in the overall VP44 fuel pump injection operating system.

• John

1 hour ago, Tim Waldo said:

So would I be safe just knowing my fuel pressure dropped below 10 psi?

Absolutely.

Reading the following may help you feel more at ease:

I have owned my truck since new and it currently has logged 402,000 miles on the odometer.

• Odometer 66,000 miles August 2004 - First injection pump set a code P0216 ( a death code for the VP44).

• Odometer 87,000 miles August 2005 - Injection pump replaced with re-manufactured unit under warranty. Lift pump relocated as an in-tank pump application (also covered under warranty).

Just prior to replacing VP44 injection pump, I monitored lift pump pressure because the word back then (similar to what is now) was that if you don't have 14 psi lift pump pressure, you are going to kill the VP44. So, I drove my truck for a week (250 miles) monitoring lift pump pressure. It operated within factory specs flawlessly and maintained 6 psi at wide open throttle at 2500 rpm.

After the replacement of the VP44 injection pump and the replacement / relocation of the lift pump as an in-tank lift pump, my new lift pump pressure was 6 psi at idle and 3 psi at wide open throttle - yes, 6 psi and 3 psi! I was not concerned because by then I had learned much about the true operation of the VP44 fuel system. According to all of the diesel forums, I should have mutilated the VP44. But, that didn't happen..., and it still hasn't happened.

• Odometer 250,000 miles April 2016 - Install Smarty tuner and set for mild tune.

• Odometer 251,000 miles April 2016 - Replace in-tank lift pump (not because of failure, but to have more readily serviceable frame mounted used FASS lift (65 gph). Note that the re-manufactured VP44 has logged 164,000 miles with maximum fuel pressure at 6 psi. Should be dead now, right? But, alas, it isn't. FASS lift pump - 12 psi at idle, 6 psi WOT at 2,000 rpm

• Odometer 303,000 miles December 2018 - Replace original injectors with RV 275's

• Odometer 402,000 miles - November 2025 - Now have logged 315,000 miles on re-manufacture VP44. Should be dead by now - right? But, again, it isn't.

I would like to note that this truck has never received fuel additives, nor 2-stroke oil to the fuel. Also, I would like to note that this truck has done lots of work covering thousands of miles at 20,000 lbs gross combined weight crossing lots of mountain passes in hot summer conditions.

Hope this helps.

• John