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  1. #1

    Does the Gen 3 have a 2 stage fuel pump

    Looking to upgrade an early Gen 2 with bad pump.

    Thanks
    Tom

  2. #2
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    Why not put another factory pump in. What hp increase do you have that makes the factory pump in need of improvements to suit your car? You also need to be aware that later fuel modules do not have the same evap connections as the earlier modules. So in fact your upgrade will in actuality be a downgrade.
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  3. #3
    My car is 511 NA and 675 on a 150 shot. The dyno chart shows the sprayed HP abruptly at 675. NX said it is a solenoid going bad. I haven't had time to debug the system. This is really pushing a stock pump to its limits from what I have researched on the internet. And it could be a contributing factor for the sprayed HP brick wall limit.

    The factory 2-stage pump and module are NLA. Used ones are pushing $1500.

    The Gen 3 has a 255 lhp pump in it - Gen 2 is 190 lhp.

    Using a Gen 3 pump is an upgrade.

    NOTE: Gen 4 is 400 lhp and is a 2-stage system, however it uses a 1-stage pump and another "ancillary" pump that is part of the basket to fill the bucket.

    The Gen 3 pump can be removed and installed in my Gen 2 basket. HOWEVER, if the Gen 3 pump is NOT a 2-stage pump, then I lose the "surge tank" functioning of the OE basket.

    Also note, that if more flow is required, a second pump should be added keeping the OE 2-stage so it can fill the basket "bucket."

    The fact that Dodge designed an in-tank "surge tank" is a great design feature and I'm hell bent on not giving it up.

    NOTE: What is worse and NO ONE MENTIONS THIS: If you replace the 2-stage pump with a 1-stage in my basket AND DO NOT put holes in the basket "bucket", you will have an "anti surge tank" which will not fill up from the bottom. It will keep the pump dry until the fuel spills over the top of the bucket!

    ALSO using a fuel mat will keep a 1-stage pump from sucking air when the basket "bucket" is empty and there is still fuel in the tank. However it can do nothing to provide the lost pump cooling when submerged in a full basket "bucket."

  4. #4
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    Are you still using stock injectors? If so, you may be going static on the stock injectors.
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  5. #5
    There was no evidence of a problem at 511 NA. The 150 shot uses fuel spray for enhancement - not the injectors.

    I should be OK I'm thinking - I keep hearing the stock setup is good to 600 NA but then also only 525 NA.

    There is very little info on what's in the tanks of these cars and only a single thread that reveals the existence of a 2-stage pump.

    If the FSM does not explain the 2-stage system operation, only a careful teardown of a OE fuel module with careful scrutiny would reveal it's presence. It would be very easy to simply replace the 2-stage with a 1-stage big pump and not know you had done.

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    Um...the pump doesn't "directly" keep the basket full, the FPR does...by design. It pees fuel directly on top of the pump ALL THE TIME...and as a result, the basket is always full regardless of how much fuel is in the tank (well that is how the 00-02 design works). The OEM pump draws fuel through the bottom sock or through the little side tit on the bottom side of the pump in the basket...all the time. The bottom sock inlet is the bigger inlet and draws the most fuel. The pump doesn't draw fuel from either the tank OR the basket, it draws it from both ports ALL THE TIME...but the bottom port is the larger so it will draw more through the sock and send it North to the FPR and to the fuel line. Any excess pressure beyond 55 PSI gets peed right back into the basket before it ever leaves the tank. Very neat design. Remember that the excess fuel being peed back into the basket has gone through the filter/pump and FPR. THat's why the side fuel feed tit on the bottom of the fuel pump in the basket doesn't have (or need) a filter on it. Its already been filtered when it was drawn into the pump through the bottom sock feed.

  7. #7
    Thanks ellowviper!

    I was starting to think the 00-02 and Gen 3 were the same after I saw a basket pic in my 00 FSM. And also suspecting the FPR was utilized to eliminate the exotic 2-stage pump.

    However, with a low tank, there may be baffling to keep fuel around the pump inlet.

    Depending on what the bottom of the tank looks like, a fuel mat could be a major improvement for low fuel situations or G's from drag or cornering.

  8. #8
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    Quote Originally Posted by ellowviper View Post
    Um...the pump doesn't "directly" keep the basket full, the FPR does...by design. It pees fuel directly on top of the pump ALL THE TIME...and as a result, the basket is always full regardless of how much fuel is in the tank (well that is how the 00-02 design works). The OEM pump draws fuel through the bottom sock or through the little side tit on the bottom side of the pump in the basket...all the time. The bottom sock inlet is the bigger inlet and draws the most fuel. The pump doesn't draw fuel from either the tank OR the basket, it draws it from both ports ALL THE TIME...but the bottom port is the larger so it will draw more through the sock and send it North to the FPR and to the fuel line. Any excess pressure beyond 55 PSI gets peed right back into the basket before it ever leaves the tank. Very neat design. Remember that the excess fuel being peed back into the basket has gone through the filter/pump and FPR. THat's why the side fuel feed tit on the bottom of the fuel pump in the basket doesn't have (or need) a filter on it. Its already been filtered when it was drawn into the pump through the bottom sock feed.
    Negative. In the 2-stage canister designs, the secondary Jet-Pump stage is what fills the fuel canister and causes it to overflow. The Primary stage draws from inside the canister, and then the return returns to the canister. As such, it has nothing to do with filling, only minimizing losses. The second stage draws from outside the canister, and flows inside with the use of a jet outlet and venturi, which causes the canister to fill and cover the primary pump inlet.
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    Quote Originally Posted by MrCreosote View Post
    Thanks ellowviper!

    I was starting to think the 00-02 and Gen 3 were the same after I saw a basket pic in my 00 FSM. And also suspecting the FPR was utilized to eliminate the exotic 2-stage pump.

    However, with a low tank, there may be baffling to keep fuel around the pump inlet.

    Depending on what the bottom of the tank looks like, a fuel mat could be a major improvement for low fuel situations or G's from drag or cornering.
    Late Gen-2 and Gen-3 use the same internal pump and basket design, just a slightly different hat length, and without springs in the Gen-2.

    None of these pumps use a "dual rotor" design which was alluded to in other posts. The second stage is a Jet-Pump, which uses a venturi and jet output from the primary pump to function.

    In Gen-4+, the second stage is actually separated out and part of the basket itself, rather than the pump.
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  10. #10
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    Quote Originally Posted by Viper Specialty View Post
    Late Gen-2 and Gen-3 use the same internal pump and basket design, just a slightly different hat length, and without springs in the Gen-2.

    None of these pumps use a "dual rotor" design which was alluded to in other posts. The second stage is a Jet-Pump, which uses a venturi and jet output from the primary pump to function.

    In Gen-4+, the second stage is actually separated out and part of the basket itself, rather than the pump.
    When we did the Gen 4 module conversion on my '01 you probably remember the length had to be increased by 1". But the connections on the top were identical since all the evap hoses etc go to elsewhere on the tank itself.
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  11. #11
    Thanks for the clarification.

    OK, so the "850 HP" thread was wrong when it said the early Gen 2 used a 2-stage pump and a surge tank design: one stage to fill basket from tank, other to fuel engine from basket.


    I wonder what Scharf means by his comment on car-part.com for a 96 RT/10 fuel pump he's selling: "damaged by customer then returned 96 RT/10 ONLY EXTERNAL FUEL PRESURE"

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    Quote Originally Posted by Viper Specialty View Post
    Negative. In the 2-stage canister designs, the secondary Jet-Pump stage is what fills the fuel canister and causes it to overflow. The Primary stage draws from inside the canister, and then the return returns to the canister. As such, it has nothing to do with filling, only minimizing losses. The second stage draws from outside the canister, and flows inside with the use of a jet outlet and venturi, which causes the canister to fill and cover the primary pump inlet.
    I think we are agreeing. I'm talking about 00-02 design. No 2-stage canister in those. Sock filter is only on the bottom inlet feed (meaning that is the primary fuel pickup for the system and it rests on that plastic circular screen bottom of the canister) and the smaller side nipple presumably pulls "some" fuel from the basket if the primary feed is restricted?? IMO, more as a fail safe I suppose if the bottom feed can't keep up for short periods. Not sure how that balance works other than possibly by venturi; but drawing fuel in, not pumping fuel into the basket. Bottom of the basket is already open to the tank and will fill by itself. Unless my tank has some weird-ass fuel canister no one else does.

  13. #13
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    Quote Originally Posted by ellowviper View Post
    I think we are agreeing. I'm talking about 00-02 design. No 2-stage canister in those. Sock filter is only on the bottom inlet feed (meaning that is the primary fuel pickup for the system and it rests on that plastic circular screen bottom of the canister) and the smaller side nipple presumably pulls "some" fuel from the basket if the primary feed is restricted?? IMO, more as a fail safe I suppose if the bottom feed can't keep up for short periods. Not sure how that balance works other than possibly by venturi; but drawing fuel in, not pumping fuel into the basket. Bottom of the basket is already open to the tank and will fill by itself. Unless my tank has some weird-ass fuel canister no one else does.
    Nope, not what I am saying. You need to look closer at the pump design.

    00-02 has the same canister design as 03-06, which has the jet-pump integral to the fuel pump. 2008+ has it as part of the module housing itself.

    In the case of 00-06, the pump gerotor draws fuel from the outer ring at the bottom side of the pump body, which looks like a screen [if you look closely you can see the gerotor behind it]. This draws from the filter sock inside the module, and pumps out the pump outlet and to the engine. The center "inlet" is the Jet Pump, as is the "nipple" that sticks out the side. These have nothing to do with pumping to the engine. The lower protrusion sticks down through the bottom of the canister and is sealed, drawing fuel from outside the canister, and propelling it out the side nipple which is located INSIDE the canister body, thereby filling it.

    The Jet-Pump is a very simple design, it takes pressure from inside the pump body, and directs it through the side nipple causing the flow through the "pull" or "drag" fuel with it. It can fill a module pretty damn fast. Works the same way any common "blow gun" for an air compressor works.

    The "cup" that is part of the sock assembly is there to prevent the inlet of the fuel pump from becoming uncovered when the pump is off and the canister level returns to tank level, as the fill nipple is located inside the cup, which means the canister cannot "gravity drain" below the top edge of said cup. As soon as the pump re-starts, the jet pump will refill the canister again from the tank contents.

    VS-1500TTvc, #001 (116).jpg
    Last edited by Viper Specialty; 01-03-2020 at 05:12 PM.
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  14. #14
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    Well...I guess I've had it wrong all these years....doesn't make a lot of sense if that is how it works...but it works! I never noticed the two red line fuel feeds on the bottom. I'll have to take a look on my spare OEM pump. I thought it was a solid piece with just the larger feed the sock fits on.

  15. #15
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    Similar to how a Gen4 pump basket operates. The basket will only fill to the level of the fuel tank naturally. The jet pump fills the basket to the top as long as there's enough fuel in the tank.

    Last edited by Back In Black; 01-06-2020 at 11:07 AM.
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