GTI Fuel Tank Feed Issues/Holley Hydramat Discussion

[arob157]

Probably nothing ground breaking, but from I gather the RS3 pump pumps fuel out the smaller port (positive pressure) on the right, and ...

Edit: or do you think the flow is opposite direction? I'm just speculating... the right port and small line going to fuel pump is on the outlet side of the fuel pump, as can kinda be seen in the 2nd pic.

And yes, legos are awesome OK. Kids play room / car parts storage room lol.

I will have to take a look at the pump this weekend. I cannot imagine the stock siphon hose plugging into the lower quick connect to pump fuel back into the tank. Otherwise fill level would be the only thing allowing fuel into the basket. Well unless the bottom of the basket has some sort of inlet. That and I can run the car down to 0% via VCDS. Usually fills around 12.5 gallons where I used to occasionally fill to 13-13.2 gallons when I tempted fate.

If yours isn't installed in the car yet, can you take a bottom and internal (top down) shot of the stock hose leading from the quick connect into (what looks to be) the bottom of the basket or pump?

And I completely get the kids toys being everywhere. Been doing logs and Draggy for runs for two weeks with two kids seats in the back lol. Always hear some sort of rattle toy flying around during spirited driving.

 

[billbadass]

@OP, are you having any fuel pressure issues with low fuel in the tank when you are just driving around normally?

I've been thinking about upgrading my LPFP so that I can run full E85, but hearing all the headaches that comes with an upgraded LPFP is keeping me at bay.

don't do it, stay with stock LPFP imo. the bad thing with fuel issues is also when fuel runs dry that's how you can nuke motors.

 

[arob157]

@OP, are you having any fuel pressure issues with low fuel in the tank when you are just driving around normally?

I've been thinking about upgrading my LPFP so that I can run full E85, but hearing all the headaches that comes with an upgraded LPFP is keeping me at bay.

No. The fuel issue myself and others are having is not unique to any pump. Even the stock LPFP can be run dry on pump gas in 4th gear. Just have to be tuned for the right power and know the limit of where/when you can run the basket out of fuel. It is dependent on fuel level and the ability of the basket to stay filled via the siphon or jet feed hoses.

My proposed solution is to lower that minimum tank fill threshold as low as possible. Might be a waste of money, but I would rather try and not succeed...you know how the saying goes.

My opinion is do not be afraid of LPFP upgrades. Just be prepared and ready as much as possible. The A2B pump is out of a stock RS3. Also isn't a new solution. Older VAG tuners have been using TT-RS pumps in other chassis's for 10+ years now.

 

[aaronc7]

@arob157

Bottom looks like a single opening, with a check valve type thing, to allow fuel into the bucket, but not out.

The smaller hose that goes to the smaller quick connect (on the right per my original photos)....goes to the pump outlet. A smaller outlet port just beside the larger main outlet, that goes into the fuel filter.

I looked at the Iroz brushless setup for the RS3, and those pumps only have a single outlet...and for those, the line coming out of the pump outlet T's off a smaller line, that goes down to that same quick connect fitting. So that seems to confirm that the line does push fuel out.

 

[arob157]

@arob157

Bottom looks like a single opening, with a check valve type thing, to allow fuel into the bucket, but not out.

The smaller hose that goes to the smaller quick connect (on the right per my original photos)....goes to the pump outlet. A smaller outlet port just beside the larger main outlet, that goes into the fuel filter.

I looked at the Iroz brushless setup for the RS3, and those pumps only have a single outlet...and for those, the line coming out of the pump outlet T's off a smaller line, that goes down to that same quick connect fitting. So that seems to confirm that the line does push fuel out.

Perfect minus the fact that I have to change courses slightly. The smaller hose is outputting fuel back into the tank to create suction in the basket/pump to draw fuel.

Since the larger fitting pulls from the opposite tank, maybe I can convert the covered port on the FWD RS3 pump.

Will have to ask Billy if I can get one of the AWD fittings and hoses/connectors so I can leverage the pickup. I could also then aim the "jet" hose at the Hydramat. It would a actively feed the mat. Or hook it up directly to the t-fitting. That would create a fuel "loop". Not sure if that would cause issues with the functionality connecting it on that way.

Thanks for the info/breakdown, @aaronc7

 

[aaronc7]

Perfect minus the fact that I have to change courses slightly. The smaller hose is outputting fuel back into the tank to create suction in the basket/pump to draw fuel.

Since the larger fitting pulls from the opposite tank, maybe I can convert the covered port on the FWD RS3 pump.

Will have to ask Billy if I can get one of the AWD fittings and hoses/connectors so I can leverage the pickup. I could also then aim the "jet" hose at the Hydramat. It would a actively feed the mat. Or hook it up directly to the t-fitting. That would create a fuel "loop". Not sure if that would cause issues with the functionality connecting it on that way.

Thanks for the info/breakdown, @aaronc7

Just my own curiosity/education.... What does that line in the tank actually connect to or do on the GTI? I am trying to figure out why Billy would have hooked that line up to it for his GTI installs.

 

[arob157]

Just my own curiosity/education.... What does that line in the tank actually connect to or do on the GTI? I am trying to figure out why Billy would have hooked that line up to it for his GTI installs.

So a jet-style pump still has to use a jet as an output for fluid to help drive the impeller. At least from what I have read. Not really sure that is was 100% required to hook up to the stock hose to be the jet, but provides a good place to retain the stock hose regardless.

I chatted with Billy and hopefully can get an AWD fitting/hose. Will probably just hook up the Hydramat to that side.

AWD cars could run the Hydramat in line exactly as I had l initially planned. FWD cars need the AWD pickup hose and a 90deg. AN fitting with a male 3/8" quick connect fitting. Need a couple more parts now, but sounds like this might be sorted.

 

[chitownfan]

Probably nothing ground breaking, but from I gather the RS3 pump pumps fuel out the smaller port (positive pressure) on the right, and the larger port on the left with the 90* fitting is the return port. A small portion of fuel constantly flows over to the driver side tank and via venturi/suction, sucks up fuel from the driver tank and returns that fuel to the passenger tank/into the bottom of the bucket. This is the same way that my C5 works... fuel from the tank without the pump is constantly being pumped over so the maximum amount of fuel is in the side with the pump. So for example, when the gas gauge says 0... the primary tank is actually still full and the secondary tank is empty. This is for the AWD saddle-style tanks of course. I'm gonna see if I can monitor each tank's level sensor voltage and see if that's actually what's going on.

For the GTI... from what I saw in the video A2B posted, the return port is blocked off and the positive pressure connects to the stock line in the tank. No idea what that does or goes exactly.

Edit: or do you think the flow is opposite direction? I'm just speculating... the right port and small line going to fuel pump is on the outlet side of the fuel pump, as can kinda be seen in the 2nd pic.

And yes, legos are awesome OK. Kids play room / car parts storage room lol.

that rubber hose elbow is best to leave off because it ends up bending or kinking inside, and you get no flow best to leave it off well from what I've experienced

 

[chitownfan]

Anyone ever try this? http://www.radiumauto.com/Venturi-Jet-Pump-Kit-P760.aspx

 

[Klrider44]

Think I just had some fuel issues because of the lackluster GTI tank. Tried doing a log with a quarter tank of fuel. I guess that wasn’t a good idea....since the car started breaking up a bit. I can’t confirm that it wasn’t my pumps fault, but I have not experienced any hesitation like that on this current tune before. Waiting to hear back from my tuner if I should be investigating more into the pump or just keep this car above a quarter tank to keep it happy. I have the RS3 LPFP btw.

 

[chitownfan]

I have the rs3 pump and I'm getting lean afr and lower rail pressure on high RPMs I'm upgrading the fuel lines to see if it makes a difference

 

[aaronc7]

what's the rest of your setup?

 

[arob157]

Anyone ever try this? http://www.radiumauto.com/Venturi-Jet-Pump-Kit-P760.aspx

The Radium fitting looks like it could allow the Hydramat to function. It would require there to be enough fuel pressure being output from the fitting at the bottom of the basket (where the stock in-tank hose attaches). The flow nozzles would then adjust the fuel pressure/velocity through the Radium fitting depending on opening diameter. Billy stated that both fittings/connections on the RS3 pump variants are outlets, and not inlets into the basket.

The Radium venturi inlet fitting would be installed onto the lower quick connect fitting. The Hydramat would be attached to the siphon fitting, then the the flow fitting would have a hose run back into the basket. There could be an issue with filling the basket with excessive force/pressure/velocity and splashing of fuel. But at least it would be feeding the basket instead of allowing it to run dry due to lower fuel levels.

The good thing about this setup would be no interruption of the fuel feed line to the fuel rail. I will reach out directly to Radium and see if this could be a possible solution.

 

[bobivy1234]

The Radium fitting looks like it could allow the Hydramat to function. It would require there to be enough fuel pressure being output from the fitting at the bottom of the basket (where the stock in-tank hose attaches). The flow nozzles would then adjust the fuel pressure/velocity through the Radium fitting depending on opening diameter. Billy stated that both fittings/connections on the RS3 pump variants are outlets, and not inlets into the basket.

The Radium venturi inlet fitting would be installed onto the lower quick connect fitting. The Hydramat would be attached to the siphon fitting, then the the flow fitting would have a hose run back into the basket. There could be an issue with filling the basket with excessive force/pressure/velocity and splashing of fuel. But at least it would be feeding the basket instead of allowing it to run dry due to lower fuel levels.

The good thing about this setup would be no interruption of the fuel feed line to the fuel rail. I will reach out directly to Radium and see if this could be a possible solution.

I know this thread is old and maybe there are others, did you resolve the fuel pump issues with the Hydramat or Radium parts? I have a GTI and looking for someone to help with fuel starve at the track without going surge tank just yet. Currently run the RS3 pump and black controller with A2B's DIY FWD harness so that second port is blocked off for me currently.

 

[arob157]

I know this thread is old and maybe there are others, did you resolve the fuel pump issues with the Hydramat or Radium parts? I have a GTI and looking for someone to help with fuel starve at the track without going surge tank just yet. Currently run the RS3 pump and black controller with A2B's DIY FWD harness so that second port is blocked off for me currently.

I haven't but still have most of the parts. I have a feeling I am gonna need to figure something out so I can run lower fuel levels with my current turbo. I had a spare RS3 pump to experiment with.

I am thinking that we might be able to leverage the jet pump location. That outlet should be relatively low pressure/flow and is already regulated. Install the jet pump off that fitting location. Then the hydramat off the siphon side. Then re-route the outlet back into the basket. Provide enough service loop to allow the hydramat to sit in the rear of the tank. I sold my used pump to a local guy who had a failing Walboro setup and have been on pump 91oct all winter. But the new turbo is flowing enough to cause issues below 3/8 tank on 93.