YXZ Stock Fuel Pump limitation after going GYTR turbo?

Rooster1 said:

I'm running 17 lbs on the stock pump with no modification. I have the gytr v1 with alba's flash, injectors, built engine, boost controller, and there cams. They claim 350 motor with this set up. So I feel you could easily keep your stock pump. I'm not sure how long this pump will last at this rate. Stock pump set around 49lbs, with the internal regulator...oh yeah this is with fresh 93 octane with accelerator.

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Thanks for chiming in, the more data the better, I bet it really wakes up around 17psi!! Have you ever monitored fuel pressure to see if it is maintaining the ~49psi that it is set for under max loads/RPMs?

My biggest concern from running higher boost ranges is that without a rising rate FPR (such with the YXZ stock) that the injectors are going to see 1psi less with every 1psi of boost increase. So in your example the OE injectors are supposed to see ~49psi, but with 17psi of pressure on the other side of them they are only performing as if they had 32psi applied (49-17=32).

Thinking initially it would be advisable to monitor fuel pressure in the following scenarios:
1) GYTR Turbo, stock fuel system, Idle through full load @7psi. Does it maintain a solid ~49psi?
2) GYTR Turbo, stock fuel system with plugged FPR replaced with external Rising Rate Regular/Return, Idle through full load @7psi. Does it maintain a solid ~56psi?

If things look good from there then keeping the OE pump as adding boost, while monitoring Fuel Pressure to ensure it is hanging in there, will be the next steps.

Had purchased a spare used YXZ fuel assembly recently to tinker with to try to get some specific answers. So today I've taken it apart and found the integrated regulator has some ports that can be easily welded (top hole/bottom hole/two bottom sides) up to avoid it bleeding off any fuel, so I've now tacked those closed with the TIG thus it should not leak down (regulate) any fuel anymore. I'd prefer to have a CNC'd part but for the sake of testing of what could be a quick one-off it will do the job.

I've also purchased a Yamaha Sidewinder Fuel Pressure Regulator used (also came with fuel rail and injectors), which I plan on using the regulator as it is a rising rate unit (with vacuum/boost reference); fortunately it bolts right to our rail as well. I am hoping this in itself will help buy some more boost, provided the OE Fuel Pump and Injectors (boost referenced) can keep up. If I do find the Fuel pressure can't keep up to demand then I will modify my spare assembly for the 190LPH High Pressure Fuel Pump (Walbro F20000141) which is rated to 87psi and seems to only use about 8amps which is only a bit more than the OE units ~5amps.

Before doing any mods and to get some baselines I went ahead and ordered the following items to install into the main feed giving easy access to test fuel pressures:

Rooster1 said:

Big Injectors / Big Fuel Pumps

So who's running oversized injectors? What was your reason for needing more juice... Super Charger, Turbo, Stroker? How about the pump, what's the best method, new external pump, and if so, do you still need the OEM in tank pump also? New in tank pump with larger GPM rating. Are you using a...

www.yxztalk.com

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Yeah, I'd bumped into that thread along with some others too. Sadly it seems that no one goes to a rising rate regulator, which should be the first thing that is done with a boosted engine (to maintain proper base pressure to the injectors). Without doing that it is nearly impossible to know where the stock injector limitation really is, whereas the fuel pump limitations itself will be easy to find with the fuel pressure gauge installed. From what I can see the OE YXZ fuel pump may have some good stuff going for it, so I am going to let it stay for a bit until it proves otherwise. If it comes to that them I will put in the 190lph HP walbro and see how that goes.

It seems that most are just doing larger injectors and flash tuning for them, but without the fuel system work (ie. adding the Rising Rate Fuel Pressure Regulator with return to tank modification). Either that or just tuning around the depleted pressure to the stock injectors (caused by the lack of boost reference to the regulator), which would make the original YXZ injectors seem to need replacement even sooner. Not to say the OE YXZ injectors will be good forever (I don't even know what cc they are?), just that with rising rate's pressure applied they would have a bit longer legs than they would otherwise.

I've ordered the AEM x-series Fuel Pressure gauge today as well, this will help the process along, and I'll be sure to document each step so the next guy has the info.

Rooster1 said:

When running my set up with a pressure gauge, I do not recall a drop in pressure even while under boost. I was trouble shooting something else, and it's hard to read a small guage under full boost on dirt.

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The fuel pressure (assuming the pump is keeping up) applied to the fuel rail and injectors will always be inline with setting of the fuel pressure regulator, so I'd agree that you should see that static on your fuel pressure gauge. In short the fuel pressure gauge is only to see if the pump and regulator are holding up their end of the deal.

The problem is however that for every psi applied via boost to the throttle bodies, ends up pushing upward on the injector pintle which affects its flow potential and spray pattern directly boost psi vs. fuel pressure psi. This means your injectors at full boost @17psi are flowing like they have 32psi applied to them (if your base fuel pressure is 49psi) thanks to the countering boost pressure.

This can be tuned around in the flash of course but the ideal way to go would be to have a rising rate regulator such that the base pressure (ie. ~49psi) is always seen by the injectors internals, this provides for proper injector flow and spray patterns (then tune for it). In this case you need a rising rate regulator which would affect your fuel pressure reading proportionate to boost pressure, meaning under full boost your fuel pressure would raise to ~66psi on the fuel pressure gauge (fuel pressure rises 1psi to every 1psi of boost). Of course the fuel pump needs to be able to keep up with that, too.

Being the type of person who likes to just prepare for what I feel is going to be eminent (in due time), I began building up a new fuel pump assembly. I'd bought a used complete fuel pump assembly from Ebay for $85 shipped to just get started, and it has worked out pretty sweet so far as the OE part can be hacked on with little effort to get the job done.

Bought a Walbro/TI 190LPH High Pressure fuel pump with harness and sock:
Pump $60 shipped
Harness $15 shipped
Sock $15 shipped
(I'd picked the 190LPH HP for its lower amperage and it should be enough for my ultimate goals)

Bought these Sumitomo MT090 terminal pins for the fuel pump to bulkhead OE connector, seems to be a common terminal and reasonable to have extras laying around anyway ($15 shipped):
(The walbro harness leads work great but are a little bit tight pushing into the connector)

This tool was awesome to crimp the above terminals just like OE ($23 shipped):

Also purchased this Gates submersible fuel hose (will need well less than a foot) to connect the pump and return ($30 shipped):

The original pump housing needs its top cut off, or hacked on to your liking to fit the pump. The way I went about it was that firstly I'd used a hole saw to cut out the top, but the pump needed to push up higher for proper sock clearance so I cut off the top next rather than sanding the entire insides out. Glad I did as at this point the OE fuel filter is exposed and can be removed, providing a surrounding "bucket" fuel can be dumped back into via the return. I'd taken dremel cut off wheels to do most of the work, some cartridge roll sanding into the pump holder cylinder up top to make the Walbro push all the way through. When said and done the pump squeezes very nicely into position and honestly seems to be a perfect interference fit, but I have an Oetiker clamp on the way that will hold around the base plastic to ensure the pumps position is held in place.

Probably have no more than 30 minutes to the hack work above, but a hell a lot more into finding the bits and pieces to get this far. The plan from here is to plant the return line into the surrounding bucket (where the original filter resided), so the pump always is cooled internally and externally as long as there is fuel the sock is able to pick up anyway, and going to run an external filter on the top side of the tank. Still waiting on the bulkhead adapters and fuel line, should only be another few moments into it to complete thereafter. Will prob still have close to $300 into the assembly alone when said and done, so not like it was ultra cheap, but will have some OE like characteristics retained and I feel will be a solid drop-in upgrade.





I've also bought a used sidewinder fuel rail/injectors/fuel pressure regulator assembly for $130 shipped. I believe these injectors are ~500cc, but will likely send them off for cleaning and flow measurements to confirm. I can not seem to find anything conclusive as to their size NOR even the size of the YXZ injectors (~400cc?). The plan is to use the Sidewinders Fuel Pressure Regular with the new pump setup, returning its fuel back into the OE fuel connection and using the new bulkhead adapter parts for the fuel feed.

[email protected] said:

As a data point, the DLP Stage 2 Turbo Kit, which comes with our 530cc injectors, at 12psi is designed around the output of the stock fuel pump system. Additional boost over our stage 2 kit we recommend upgrading the pump, which is required for our Stage 3 turbo kits.
We teamed up with Aeromotive to have a drop in pump option with and without lines and regulator:

Aeromotive 200lph fuel Pump with YXZ1000R drop in module for Yamaha YXZ1000R

Find high performance parts for Yamaha YXZ and Can-Am off-road UTVs. Exhausts, turbo kits, suspension, drivetrain, engine performance and more!

dirtlaunchpowersports.com

Aeromotive Fuel Pump kit for Yamaha YXZ1000R

Aeromotive’s Phantom Series direct drop-in fuel pump modules for Yamaha YXZ1000R models feature a factory-sized outlet cap to maintain fitment with the OEM fuel tank.

dirtlaunchpowersports.com

Our GYTR Stage II Upgrade offers similar performance as our Stage 2 kits, utilizing the stock fuel pump:

Dirt Launch Powersports GYTR Turbo Boost Upgrade

Upgrade your ECU with this programmable tuner from Dirt Launch Powersports. Available now!

dirtlaunchpowersports.com

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Thanks for the info, always cool to see vendors share info and offer solutions for the platform. When it comes to 12+psi needing the regulator/bigger pump, I'd assume that move onward is mostly due to the fact that the 530cc injectors are really starting to not flow nearly as well because of the 12+psi boost working against them (without the 1:1 rising rate regulator), and with the 1:1 regulator the pump is getting to the point of not being able to push the volume nor maintain the (further demanded) pressure at these levels either. This is what I'd expected to see and was trying to be prepared for it as well, I currently have the full AEM gauges (WBO2, Boost/controller, Water temp for liquid air IC, and Fuel Pressure).

I do believe that the (spare) sidewinder injectors I bought are right there in size with injectors you have as part of your Stage 2 kit as well (~500-550cc), ultimately I am thinking around 12psi is where I will probably be stopping. Of course the fueling/ECU becomes a huge thing with the injector swap, so I was hoping to find out just how for I can get with the OE injectors with the 1:1 regulator and 190lph pump installed first.

At any rate good on you guys for offering more options and packages, most all want something "turnkey" just like that as well. I am sure when I get to the end of where I am heading I'll say "should've just bought that kit".

RobBeck said:

Erik, do you know if anyone has ever tested to see how much power can be made (or roundabout boost limits) with OE injectors BUT with the proper pump and 1:1 regulator in place?

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Our own testing we built our stage 1 kit around the stock fuel system and injectors. As we also wanted our Stage 2 kit to use the stock fueling system so we increased the injector size to 530cc.
We did some testing way back in the beginning of developing these kits with higher fuel pressure but we felt it was just a better option to increase the injector size. I'm sorry I don't have the data from that testing.

The sidewinder injectors are 450cc.

The YXZ's competing in the Championship Off-Road Series in the Pro-Turbo class are using a DLP upgraded Gen 2 GYTR kit. The turbo and manifold are from the GYTR kit, everything else (intercooler, lines, fuel system etc...) is from our DLP kits. That setup uses Sidewinder fuel injectors with the Aeromotive fuel pump kit we offer, with fuel pressure set to a static 50psi (this is regulated by the rules).

With our fuel system and the FPR referencing boost pressure we could get more out of the stock injectors, but when putting together a turbo kit we preferred to upgrade the injectors instead.

Our stage 3 does both, upgrades the injectors and uses the DLP / Aeromotive fuel system.

[email protected] said:

Fuel pressure is set to 50psi with no vacuum line attached, again this is per the rules to govern the power output.

Right now the only tune we have for the GT25 and that manifold is with our intercooler, the sidewinder injectors and the aeromotive fuel system. I'd need to get my hands on a GYTR Gen 2 intercooler to put that tune together.

It's on the schedule to install this setup without the fuel system and do some tuning with the stock injectors and our intercooler, but with race season and other products we're developing I'm still waiting to finish this project.

Or you can always bring your YXZ to us, Beyond Redline Performance is our sister company where we do all of our tuning.

Performance | Beyond Redline Performance | United States

www.beyondredline.com

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If your tune is pretty solid for the GT25, it would be well enough for the GT28 as well, both are very well under their efficiency ranges at the flow levels we are considering here. On that note even the GYTR Turbo Gen 1 vs. Gen 2 ECU's are identical, meaning that there are literally no changes with their fueling tables, at least this is what I'd seen when comparing the read ECU files of each in FTecu. I credit this to what is really just a pretty basic ECU and in that all of these tunes are pretty crude (ie. always make it rich and safe as a compensating factor).

I also do not think the Intercooler will make much difference, especially not at sub 15psi. I am sure there are claims out there but I have a hard time imagining there is some glaring defect in the Air to Water setup on the GYTR kits, especially as long as the water temps are manageable which is why I went with the Gen 2 Heat Exchanger up front with fan, to give better heat suppression in the IC's Cooling system. So far this setup seems to be working well as I dont really see water temps over 110* as of yet, and that is pounding on it hard for very long durations of time. In most normal riding scenarios I am seeing about 10-20* over ambients, while I need to watch the IAT's more over the IC water temp the bit I have looked at them they were fairly well inline with each other. I would agree that the Air to Air setup has to be much more simple, but truth be told I feel it is a step backwards in my case.

My biggest concern would be if you did not have a tune for the vacuum referenced FPR, this would likely cause the largest variances, although if it were referenced that would just make it richer (which is better than too lean). You mention that you do have a tune "for the GT25 and that manifold is with our intercooler, the sidewinder injectors and the aeromotive fuel system", but I suppose that is with the FPR unreferenced. If you do have one with the FPR referenced as well that could be a very close tune for me to work with alongside my bucket list mods, hell it may even be worth trying with my setups FPR referenced. A bit more fuel there would just get me a bit more headroom when under boost. I really am looking for a smooth way to implement the slightly larger sidewinder injector as I'd like to get to around 225-250hp PEAK sometime this year, I have had a hell of a time dealing with FTecu but if there was some way to collaborate with what you have on that front I'd be all about trying it.