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2017 5500, 80k miles fuel rail pressure issue truck is surging and won't run

1453 Views 14 Replies 3 Participants Last post by  Sean Steinberg
2017 5500, 80k miles.

Fully deleted the truck, head studs, valve springs, AirDog 4g2 last week.

First week out truck was doing great.

Then as it got colder, rail pressure was dropping.

Figured this was due to colder temps, but at 60-70* was a total dog and would barley move. Once tank was below 1/4 and fuel was warm ran fine.

Already have a BD Diesel fuel heater on order. But don't think those temps would thicken the fuel that much???

Put a fuel rail plug on also.

That was about a 3000 mile trip.

Now 300 miles on the next haul, truck wont run. Day started off fine, but have had a surging get worse and worse where now I can't do 30mph.

Idles fine, rail commanded pressure vs rail pressure pretty close on display.

No smoke colors from tail pipe.

Trying to move rail pressure is under 3k sometimes. But in park can get to 13k+.

Checked all the fuel fittings and wires.

Currently down trying to find a shop to work on it.

Any ideas?
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Where’d you run the return from the cp3?

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What happens to fuel pressure if you unplug the FCA?

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If it spike to 26k unplugged, and settles back down when when you plug it in, it should be good

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If the pressure spikes when you unplug the FCA, and settles back down when you plug the FCA back in, it should be functioning properly.

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Airdog trouble shooting:

Loss of Fuel PSI/Running Out of Fuel

Initial question: Do you have flow from the PureFlow product?

If the answer is yes, where is the location of the gauge port being used?

The gauge port in the filter housing will not work when the fuel is routed around the stock fuel filter housing.

The gauge port utilized may not be in the pressure stream of fuel.

The pressure gauge is not reading pressure.

The vehicle is receiving fuel; however, the pressure relief for the pump (ex.: VP-44 / CP-3) is open and allowing fuel to return to the tank through this pump.

Pinch the line going to the pressure pump to stop the flow of fuel after the pressure gauge. Remove the relay from the unit's wiring harness. Place a jump wire between the red and yellow wires in the relay socket. Read the pressure in the dead head mode.
If the pressure goes up to the desired pre-set pressure, the problem is indicated to be with the pressure pump relief mechanism.
If the pressure does not show on the gauge, the problem is indicated at the unit or gauge. Check to another gauge.

Check the line connections. Engine to engine. Tank to tank.

Remove the Return to "Tank" fitting. Spring and ball in the pocket? Properly seated?

Remove the gerotor cap. Is the gerotor turning?
If the electric motor is running and the gerotor is stationary, pull the center gear off the motor shaft. Is the flat inside the gerotor center gear rounded or missing?
If the electric motor is running and the gerotor is turning slowly, check the voltage to the motor. Low voltage will reduce the motor RPM's; hence, reduce or stop pressurized flow.
If low voltage check the wiring connections and voltage regulator.

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I would not, that’s just to find out if the FCA is working or not.

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