FX Nytro Fuel Pump Upgrade Questions

[Krummy]

I have a 2009 FX Nytro with an MPI supercharger and i believe i am running out of fuel (Fuel Pump). I am running at 6-6.5 psi with the gems controller pretty much maxed out. I am running a modded ecu to pull the timing and i am seeing a very consistent 12.4 afr at WOT. With that said, my plan would be to ideally run the sled at 8-8.5 psi. Are there any replacement in-tank fuel pumps for the nytro that would be able to feed an additional 2 psi over my stock pump? Am i stuck having to upgrade to a in-line fuel system with a fpr? I never plan on going higher than the 8-8.5 psi. Any assistance on this would be great. Thanks

 

[mbarryracing]

You ARE running out of fuel, the stock fuel system can only fuel to support 6-7 psi of boost. Always say the AFR drift above 12:1 at anything above 6 psi
Not sure what upgrade in-tank fuel pumps are available, didn't go that route but MPI likely has a recommendation. I used the Fuel System Upgrade from FPP, which was a boost referenced FPR, an external in-line supplemental fuel pump, and an end fitting to convert the fuel rail to a return system... Didn't have to max out the fuel controller anymore.

 

[full tilt viper]

I think your fine @12.4

 

[Krummy]

I am at 12.4 running 6-6.5 psi with everything maxed out. If i am looking to increase to 8-8.5 psi, it will only get worse. It looks as though an in-line kit is my only option in order to gain the extra couple psi. Any recommendations of kits? It appears MPI is out of them. Is there any easy way to make the kit myself? MSD pump, anyone know a good fpr to use? Anyone have an old kit laying around? Any input would be great. Thanks

 

[mbarryracing]

I'd say that at 12.4 and maxed out on the fuel controller / 100% duty cycle on the injectors you are NOT fine... the reason i say that because is the colder the intake air temp gets, the leaner you will also get and with no room to adjust, let alone any safety margin for variation in fuel quality / detonation...
If you make your own upgrade, the only item that will be tricky to fab will be the fuel rail end cap fitting so you can flow fuel thru the rail back to the gas tank through the FPR, the conventional method. However, there are OEM returnless fuel systems that have the fuel rail inlet T-d off before the FPR (instead of typically running thru the rail then the FPR back to the tank) so the rail remains returnless... They do this to eliminate recirculating hot heat-soaked fuel from the rail creating vapors in the tank... The returnless systems on all our sleds are like that, just the regulator is built into the sending unit in the gas tank instead of externally... same concept.
You could build yours using that methodology and forget having to screw with the rail.

The MSD pump is a good choice, I run that as a single pump, not upstaged (lifted) inline., but it will work fine.
There are also a few rather inexpensive boost referenced FPR's out there. I have used a Tomei in the past, currently running an AEM with my current setup.

 

[Krummy]

Thanks for all the input. I read on here somewhere that dave at hurricane offers the fuel rail end cap fitting. I may give him a buzz and go from there.

 

[Krummy]

This would not be my ideal setup, but has anyone tried a replacement intank pump such as the ones linked below? Like i said, i am only looking for an additional 2 psi. I am still trying to figure out an inline with a fpr but was hoping something below might work in a pinch. Any thoughts?

http://www.highflowfuel.com/i-23900...gUSpOMZ4IZPnxm4Gwodju_EFwnjMabTR8aBoCkq3w_wcB

https://www.google.com/search?q=nyt...&ved=0ahUKEwiQgNTAgtXRAhUByoMKHaukBE8QgjYI8QI

 

[mbarryracing]

Krummy,
To make a call you really need to compare the fuel flow vs pressure ratings to the stock pump, otherwise any replacement pump might not be any improvement over stock, just what they say... a replacement... same rating. They didn't show any fuel flow ratings so its a gamble.

Since the Nytro stock fuel system has a lack of a rising rate FPR (doesn't change pressure with vacuum or boost) it stays the same pressure. Keep in mind that at a stock 46 psi fuel pressure and at 8 psi manifold pressure the tip of the injector is equalized out and literally only operating/flowing at 38 psi fuel pressure... You'd need a pump that is rated to provide more flow at less than stock fuel pressure...

I'd think it would be less hassle to just bite the bullet and either buy a fuel system upgrade or build one.
http://snowmobile.off-road.com/snowmobile/news/nytro-fuel-kit-from-mountain-performance-35213.html

 

[Krummy]

I agree that would be the way to go but last i spoke with MPI and Ulmer, neither had a kit available. I tried getting ahold of hurricane to see if he had the fuel rail end cap but never heard back. I understand what you are saying regarding the fuel pressure. My only hope was that the kemso fuel pump claimed the flow 20% better than the stock pump but at the same 43 psi. Wasnt sure if that would be a cure or not. Thanks

 

[Jakelfin]

I have kemso pump and it is really stronger than stock pump, but I have some power/gas cutoffs with my system. Also have rising rate fuel pressure regulator which may cause the issue, if the pump or relay has some overcurrent safeback system or something like that. Fuel pressure is rising near 60psi under full boost, so it may cause some troubles. Stock pump never got over 55psi and under boost it only got lower. I have upgraded my attitude control box to pcv pti system with wideband2 autotune setup, so now I can set fuel pressure lower to get it right from bottom to full boost. Boost is going to be 13 psi, now I have to keep it about 10 to keep afr readings under 12.

 

[Blownhard]

I have kemso pump and it is really stronger than stock pump, but I have some power/gas cutoffs with my system. Also have rising rate fuel pressure regulator which may cause the issue, if the pump or relay has some overcurrent safeback system or something like that. Fuel pressure is rising near 60psi under full boost, so it may cause some troubles. Stock pump never got over 55psi and under boost it only got lower. I have upgraded my attitude control box to pcv pti system with wideband2 autotune setup, so now I can set fuel pressure lower to get it right from bottom to full boost. Boost is going to be 13 psi, now I have to keep it about 10 to keep afr readings under 12.

Hey Jake I’ve got a question
If I’m running max 6 lb of boost how should I set my pcv pti fuel pressure table? I have an external pump MSD return system.The map setup by hurricane 0 to 88 @ wot seem ok. Having a hell of a time getting it to run properly . Any info would be appreciated
Luc

 

[Blownhard]

I'd say that at 12.4 and maxed out on the fuel controller / 100% duty cycle on the injectors you are NOT fine... the reason i say that because is the colder the intake air temp gets, the leaner you will also get and with no room to adjust, let alone any safety margin for variation in fuel quality / detonation...
If you make your own upgrade, the only item that will be tricky to fab will be the fuel rail end cap fitting so you can flow fuel thru the rail back to the gas tank through the FPR, the conventional method. However, there are OEM returnless fuel systems that have the fuel rail inlet T-d off before the FPR (instead of typically running thru the rail then the FPR back to the tank) so the rail remains returnless... They do this to eliminate recirculating hot heat-soaked fuel from the rail creating vapors in the tank... The returnless systems on all our sleds are like that, just the regulator is built into the sending unit in the gas tank instead of externally... same concept.
You could build yours using that methodology and forget having to screw with the rail.

The MSD pump is a good choice, I run that as a single pump, not upstaged (lifted) inline., but it will work fine.
There are also a few rather inexpensive boost referenced FPR's out there. I have used a Tomei in the past, currently running an AEM with my current setup.

General info
09 nytro Mpi turbo @6lb boost
MSD external pump return system running 430 cc injectors
Pcv pti auto tune unit
The fuel pressure table is stumping me any help would be appreciated
Luc