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Odd "stumble" scenario

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This is an odd circumstance I am experiencing. After I refuel (usually before 1/2 tank) sometimes, perhaps one in 4 fuel stops, right after, I get a "stumble" on acceleration. Any ideas on this? Also, I dont trust the lift pump, but dont want to re-enginner the truck. Thoughts on the FASS DDRP 02 direct replacement pump?Thanks!

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FASS DDRP is not worth it... :spend: Actually you might be fighting a air leak in the system...

I thought maybe it was heat soak in the VP44 computer. Why not the FASS?
  • Owner

Because there is a few problems with FASS DDRP...

[*]Doesn't have a lifetime warranty.

[*]Doesn't deal with the retrictive plumbing issues.

[*]Only put out 45 GPH compared to AirDog, Raptor or Full FASS at 100 to 150 GPH (Stock Carter is only 35 GPH)

[*]Still mounted to far from the fuel tank no pump is capable of sucking from from the tank without failure.

Bosch requirements was to have at least 70% of the fuel returned to the tank. Hmmm... So the maximum GPH I see is about 22-25 GPH at WOT so with a FASS DDRP you not getting any extra fuel for cooling and lubricanting purpose so the VP44 take it in wear and heat.

Typically a good fuel system should only drop 2-3 PSI from idle to WOT... I bet you dropping more than that... The last person I talked to with a FASS DDRP was 18 at idle and dropping below 5 PSI at WOT with stock injectors and no box...

Fuel pressure loss points out one thing... You demand volume is greater than the pumps supply volume.

Here is what it should be like...

http-~~-//www.youtube.com/watch?v=iRoZlLVVxiY

I typically idle at 17.5 PSI at WOT I might tip 15 PSI... Still got the overflow valve open and flowing plenty of fuel back to the fuel tank keeping the electronics cool and the pump well lubricated with a mixture of diesel and 2 cycle oil... :thumbup2:

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    • Like 1

    This is an odd circumstance I am experiencing. After I refuel (usually before 1/2 tank) sometimes, perhaps one in 4 fuel stops, right after, I get a "stumble" on acceleration. Any ideas on this? Also, I dont trust the lift pump, but dont want to re-enginner the truck. Thoughts on the FASS DDRP 02 direct replacement pump? Thanks!

    Do you have a fuel pressure gauge? Without one it is really hard to diagnose the problem. Any codes?:shrug: I wouldn't go with a DDRP. Heard too many bad things about them. Get a Raptor or an AirDog imo depending on what your plans with the truck are.:thumbup2:
    • 3 weeks later...
    • Author

    Do you have a fuel pressure gauge? Without one it is really hard to diagnose the problem. Any codes?:shrug: I wouldn't go with a DDRP. Heard too many bad things about them. Get a Raptor or an AirDog imo depending on what your plans with the truck are.:thumbup2:

    No codes, no fuel pressure gauge. Only seems to happen after fueling up. I am running two stroke oil, Edge Mileage Max ( could that be it?) and 4" MBRP Ex.

    No codes, no fuel pressure gauge. Only seems to happen after fueling up. I am running two stroke oil, Edge Mileage Max ( could that be it?) and 4" MBRP Ex.

    Well for one thing you NEED a fuel pressure gauge!!!!!!:ahhh: I would try to remove the Edge just to see what happens. Also have you changed the fuel filter?:shrug:
    • Author

    Well for one thing you NEED a fuel pressure gauge!!!!!!:ahhh: I would try to remove the Edge just to see what happens. Also have you changed the fuel filter?:shrug:

    I think I am going to just do an Airdog, draw straw, and bigline kit (with a gauge) as a preventative measure, then see where I am at.
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