Fuel cut around 5,000 RPM

[KrayzieFox]

You don't you just upgrade the pump for sufficent fuel delivery? The injectors are most likely not maxed. Plus if you upgrade the pump the rrpr would actually be able to have adjustments made. It sounds like your just running out of fuel.

Good point. With a better pump I could fully take advantage of the entire range of adjustability on the BEGi RRFPR. Injectors just came to mind first cuz they're really easy to swap.

 

[Wagonbacker9]

only if a bigger pump is going to give you more pressure... not sure how all that works.. (RRFPRs are definitely not my forte)

 

[KrayzieFox]

only if a bigger pump is going to give you more pressure...

Also a good point.

I think my problem is the fact that the FPR increases pressure based on boost, but the WGA keeps the boost constant at WOT. However the 626 IM doesn't have constant airflow as it allows for a whole lot more air at higher RPMs, but I'm already at full boost BEFORE peak torque is reached. So the RRFPR doesn't ever see this extra airflow past full boost .. and therefore I get my lean spot.

Does that sound like a reasonable/possible explanation of what could be happening?

 

[Wagonbacker9]

the injector pulse should be lengthening itself as the torque goes up (this is how extra torque is made)... but it just might not be ENOUGH.

 

[KrayzieFox]

the injector pulse should be lengthening itself as the torque goes up (this is how extra torque is made)... but it just might not be ENOUGH.

Soooo.. I should try stronger injectors? LoL..

 

[KrayzieFox]

I'm just gonna wait until I get that fuel pressure gauge. I need better data to effectively troubleshoot what's going on.. cuz without that vital info, we're just running around in circles between the pump, injectors & FPR pressure.

Thanks for all your help guys, especially you wagonbacker. You're been a great help, thanks for contributing (2thumbs)

 

[Wagonbacker9]

yeah, other than gathering more info I don't have anything else more to add..

 

[KrayzieFox]

Well I placed an order for the fuel pressure gauge. Hopefully it comes this week so I can do the install over the weekend and have some more data available.

 

[JCell]

sweet.... i installed mine on the fuel line... been given me good readings for 4 years

 

[KrayzieFox]

Well, let's get this topic activated once again.

I finally got all the accessories I needed to install my fuel pressure gauge, and I finally have some more data. The gauge is setup right before the fuel rail, so it's showing the output pressure of the pump right before it hits the rail.

Anyway, at idle the pressure shows ~34 psi. At the transition point (0 inHG /0 boost) it's around 40 psi and at WOT (6 psi) it caps off at ~64 psi. Seems a bit low, even for only 6 lbs of boost. But, the fuel pump is nowhere near maxed out at that pressure.. I'm sure it can handle at least 90-100 psi right?

 

[JCell]

actually... thats high


im at around 22 at dle, 30 crusing, 37 at WOT coming down to about 30 as the RPMs reach redline

 

[Wagonbacker9]

actually... thats high


im at around 22 at dle, 30 crusing, 37 at WOT coming down to about 30 as the RPMs reach redline

you're on a stock regulator, aren't you?

 

[JCell]

unfortunatly... what are my options for upgrade?

im gettin the walbro fuel pump soon

 

[KrayzieFox]

actually... thats high


im at around 22 at dle, 30 crusing, 37 at WOT coming down to about 30 as the RPMs reach redline

How much boost? What did you tune with?

 

[JCell]

7.5 psi
untuned unflashed MSP ecu

 

[KrayzieFox]

Well that doesn't make a whole lot of sense.. my fuel pressure is pretty much double compared to yours but yet I run super lean in high RPM for some reason? I think I'm gonna replace my fuel injector o-rings just to eliminate that possibility. I never replaced them when I swapped manifolds so maybe they're not sealing properly?

 

[slo03.5msp]

He's also on an msp ecu! Which is programmed for the extra fuel. And he's unflashed which means he's dumping even more! Does I would upgrade your pump!

 

[KrayzieFox]

I would if I had any reason to believe it would actually help.. but the stock pump isn't even maxed out, so why upgrade? Unless a better pump, Walbro?, would provide me higher psi throughout the powerband.. not just maximum output.

 

[Wagonbacker9]

Well that doesn't make a whole lot of sense.. my fuel pressure is pretty much double compared to yours but yet I run super lean in high RPM for some reason? I think I'm gonna replace my fuel injector o-rings just to eliminate that possibility. I never replaced them when I swapped manifolds so maybe they're not sealing properly?

basically your higher fuel pressure is designed to push more fuel in over a shorter injector pulse. His lower pressure puts in (in theory) about the same amount of fuel. TOTALLY different engine management solutions.

 

[Wagonbacker9]

I would if I had any reason to believe it would actually help.. but the stock pump isn't even maxed out, so why upgrade? Unless a better pump, Walbro?, would provide me higher psi throughout the powerband.. not just maximum output.

the pump has one limitation: max flow. The regulator is what dictates the pressure. if you can't get the regulator jacked up any further, pump will only help if your current one is overtaxed.