WR fuel pressure system questions

I'm gearing up for a long ride on the WR...TAT and BDR kinds of things through the US. I've noted some of the things that have gone wrong from posts and videos of other riders. One of those was a failed fuel pump. I know...they go 100,000 miles but sometimes they don't and a failure can cost the trip and did for one doing the NEBDR last year...and it was a new WR. He'll never go without a spare now...so I got one also. Cheap insurance, it's small and light. No problem. Next up is the fuel pressure regulator. These, too, "never" fail. Except, well, check the forums. The regulator is tiny and light and it seems to be hard to find one with the right pressure setting that doesn't come with a largeish chunk of the rest of the engine attached !$$ And Beware the Quantum one you're looking at at the moment. Hard to find? It's right here and just $29.00 but hold on. Notice that no pressure spec is mentioned in the ad. Could this be an issue? According to the WR250R service manual, there is no tolerance on the pressure. It's 35.6 psi and no fiddling around...which both Quantum technicians and your personal mechanic will tell you is unusually low, i.e. special. Quantum did get back to me with a spec: theirs is set at about 55 psi.(!) So....
I think, and correct me if I'm wrong, that without knowing what the Air Fuel Ratio is, the engine as set up stock is fueled per the fuel pressure in the system. Increase the fuel pressure by installing Quantum's "drop in" replacement and you'll be running too rich, all the time, which may have negative down stream consequences. So we go on a hunt for a replacement that is either adjustable or is manufactured to the original specs. I've not yet found one that doesn't also come with the fuel rail or or and, the throttle body.

But what if the engine is fueled differently? I installed a Power Commander. We're now fueling to a map, the electronics controlling the Air Fuel Ratio per what it reads from the O2 sensor I installed in the exhaust pipe. What would it matter if the pressure in the fuel rail is higher than stock on my bike? I think my bike's fueling method will take care of some change in the fuel pressure and open up my fuel pressure regulator options. Maybe I can use the Quantum replacement. So that's the question. Can I just use the higher pressure regulator b/c my bike's fueling method will adjust for it? And by how much can my new fuel pressure be different and still be able to be compensated correctly by the different fueling method?
We'll stop there though there is the additional practical question you are about to ask of just how to install the replacement regulator. Bend all those stiff friggin little metal tabs out, remove the old one, push in the new one and bend all those little metal tabs back around it? 100 miles out at the side of a desert road? Alone? By headlamp? Okay, desperate measures in desperate situations, but I wonder. One question at a time. What about this fueling thing?

Easy solution: get the OEM pump assembly, which contains both the pump and the pressure regulator, and you're set for your trip. Sure, it's more expensive than getting an aftermarket pump and pressure regulator, but how much do you value peace of mind?

Thanks for the reply. In reviewing this I find that I'm unsure where the fuel pressure regulator is on the motorcycle and the service manual doesn't identify it well. I hadn't thought it was in the fuel pump assembly. I have a call into my m/c shop and their stable of m/c gurus to sort that out. There's no mention of a fuel pressure regulator in this ad for the assembly you suggest: https://www.ebay.com/itm/273490605877
but it might be in there and not on the fuel rail as I'd thought. I'll post what I learn.

  Meanwhile, though, a related question is about how the motorcycle's FPR now works with the different method of fueling. That pressure might not be as critical as it seems to be in the OEM set up which is without an electronic fueling control based on the O2 sensor and a fueling map.

The fuel pressure regulator is part of the fuel pump assembly, in the link you provided it's the black round piece at the top left of the picture. It is not sold as a separate item, so it does not have a P/N associated with it, and it therefore will not be referenced in any diagram.

Moreover, the fuel pressure regulator does not "work" differently based on fueling; the regulator is a simple spring-loaded mechanism that shunts extra fuel back into the tank when pressure from the fuel pump exceeds 36 PSI.

Where are you based? You had mentioned TAT and BDRs, so I had assumed you were in the US; WRRs in the US never came with O2 sensors, so the ECUs do not automatically adjust to fueling issues. If you installed a Quantum fuel pressure regulator that is set for 55 PSI, the fuel mixture will be extremely rich and the ECU will not compensate for it.

BTW, if you plan to buy a fuel pump assembly, get it from a reputable reseller, like servicehonda or Rocky Mountain, not from eBay; bonus is that it is cheaper at those stores.

I did finally find it. I'd never had the fuel pump assembly out of the tank but I'm installing a larger tank so I have to...and I have the opportunity to learn yet more about my WR. I recognized it immediately.
I am fueling differently b/c the bike wasn't running well. That's a long story. I have made a number of changes including the "standard mods," which, in MHO, are worth doing but I'm new to all this. I live in Vermont. This bike is an '08. I bought it three years ago with 350 miles on it. It was ridden by nobody knows who, a clutch lever was broken and replaced improperly, then it was set aside for a decade. Potential problems abound and I did have a few. Perhaps this is one reason I'm trying to be thorough about learning what might go wrong and what to do about it. One, a nasty one and quite a puzzle, was the bike's habit of quitting after an hour's ride, always in traffic when I needed the power the most. Nobody could figure out the problem so I began doing what nobody wants to do: replace every suspect a piece at a time. I also had several fuel associated parts professionally cleaned...like the throttle body and the injector. In my accumulating stash of parts I now have a used (but perfectly good) ECU, a new injector and a used spark coil. I'm casually thinking of putting the coil in a little glass case with a smiley face on it.
Turns out the coils can develop intermittents that don't open until the coil warms up.
The O2 sensor: If anybody out there wants to know how their WR runs when it can breathe freely, simply take the air box door off and go for a ride. She'll be a little loud but, oh my. You'll want to make that performance permanent. So I did the standard mods. Part of that was to change the way the bike was fueled. I added a power commander and an AutoTune unit. The fuel map has turned out to be simple. She runs beautifully, and, importantly for the kind of riding I like to do, reliably finally. The AutoTune unit requires an O2 sensor be installed. Now we're fueling to a map. All the niggling throttle hesitancies are gone. (I'd almost forgotten about them.) I'm installing a larger fuel tank so have the opportunity to learn about the fuel pump and pressure regulator. If the bike now fuels to a map per the O2 sensor, maybe a number of FPRs will work, so I thought I'd ask the forum.

The Quantum fuel pressure regulator is the only one I know of that fits the WRR, and if you decide to go with that, you will have to alter your fuel map. I don't know what the capabilities of the AutoTune unit are, but all such automated systems (including car ECUs) control fuel delivery only during steady state, i.e constant RPMs; you have to manually set the unit for acceleration inputs.

FWIW, I have changed both my fuel pump and fuel pressure regulator because they both failed, but for long trips I have a complete OEM fuel pump assembly as a backup because replacing the fuel pump and pressure regulator in the field is something that I don't want to deal with.

That makes so much sense that I'm surprised this hasn't come up before and that I had to start this topic to learn. Yes, if I put in a fuel pressure regulator set to a different pressure than the stock one, I'd have to auto tune again to get back onto the map. For me, that should be just the flip of a switch and AutoTune will change the on time for the injector appropriately. I'll check to make sure this is correct and if AutoTune can accommodate such a large change in fuel pressure. If so, I'll benefit in that my pump and the FPR will be lighter and take up less room in my panniers than an entire assembly. The FPR appears to be easy to replace in the assembly but the fuel pump itself is more troublesome requiring a couple of special tools. All this goes in to the compromise bin. While I have the old fuel pump assembly on the bench I'll see what I can learn about it and replacing components of it.
Thanks for helping me out with this.

This topic has come up before and we have discussed it.

Good luck with your adventures!

I had thought it must have but got nowhere on the site when I searched for "pressure" or "fuel pressure." I don't use the site often so probably missed something or queried into the wrong part of the site. And I appear to be search term challenged.

I'd said I'd report what I'd learned about the fueling and will do that here. This might not be as thorough as we'd like but it's a good start. Dynojet wrote this in answer to my question:

"Dec 30, 2021, 9:58 AM PST

Hello Paul,

Your AutoTune will correct any modification changes you make on your bike. The AutoTune will always correct your Fuel Table to your Target AFR values you have set."

This begs another question, maybe several. For one thing, this ability of AutoTune might mask a failing pump or FPR until the offending unit just plain quits, no warning. Knowledge + maintenance should solve that one.

So I'm going to go ahead with my plan to replace the fuel pump and FPR in the plastic housing. This is an experiment, of course, and I'll have to keep in mind that I've done this. That's the way with this used bike. The more I know, the more able I'll be to sort out issues on the road. There's a limit. I'm not a seasoned motorcycle mechanic. I won't be ready for every possible failure.
Yesterday I replaced the (still good) OEM fuel pump and fuel filter with a new aftermarket unit. The "old" one will be my spare. We know it runs. The fuel filter was/is black. From what I've seen in videos this means it's dirty. They're cleanable but also not expensive provided aftermarket replacements are good quality. One came with the replacement fuel pump.
Replacing the FPR will be easier. I'll do it given the odd history of my WR. There are few miles/hours on my WR's components but not being run for 10 years puts question marks on a number of components, especially these. As mentioned above I've already had the injector and throttle body cleaned professionally as a part of the process of chasing down an earlier problem.