Fuel Pressure Regulator Modification

[drjfjr]

I recently started testing a Fuel pressure regulator for Turbo City. It increases the fuel pressure to the injectors by I believe 5 PSI thus richening the mixture a little. I found that this device eliminated the slight surging I had in the 25 to 30 MPH range and has made throttle control from on to off and off to on transitions more linear. I have only put 300 miles on the unit and it is winter but I will keep you informed. I believe this with the Barbarian jumper mod could be used instead of the Power Commander. I have lost about 2 miles per gallon with this change, which is right in line with what I was expecting.

The ST1300 community has been using this upgrade since last spring and you can check their comments on their site.

I have iridium plugs, and Barbarian jumper mod at +7 as the only engine modifications. Installation only took me ten minutes.

I do not work for Turbo City but I thought this could be an alternative to the Power Commander.

For any questions on the product itself you can contact [email protected].

DRJFJR

 

[fossilrider]

Which unit are you testing and was it a direct fit?

 

[trimmantom]

What is the cost?Can it be used in conjuntion with a pc111 to improve that option?

Sounds like a good alternative to the pc111.

 

[drjfjr]

The Fuel pressure regulator is actually a Yamaha part that has the pressure adjusted to 5 PSI more than the stock unit. I am testing the unit for Turbo City an I do not know what he will charge for the product. I believe he is trying to get an indication of the interest in this so he can determine the price. He has done group buys for the ST1300 group and I would guess he would do the same for our group. He originally posted at the other board for testers and I volunteered. I am quite pleased with it so far and it still is closed loop instead of open loop for the power commander. That is basically what convinced me to try it.

DRJFJR

 

[Warchild]

Er...... uh.....

 

[drjfjr]

Er uh what?

Fuel pressure regulators can be calibrated to different pressures if you have the equipment. I am guessing this is the question.

 

[radman]

Adjustable regulators have been used on hi-perf auto EFI for ages. The key being adjustable though-not that hard to overwhelm the injectors spray pattern and just dump a bunch of fuel in. I know I'd be more receptive to an adjustable rather than a fixed pressure setting.

 

[Warchild]

Fuel pressure regulators can be calibrated to different pressures if you have the equipment. I am guessing this is the question.

No, that's not what I'm referring to....

It's alluding to the idea that this higher fuel pressure regulator, in conjunction with the Barbarian Mod, is a substitute for the Power Commander. That's hardly the case. For two main reasons:

1) While the Barbarian Jumper Mod has had a lot of press over the years, there are some aspects about it that many don't understand (or want to come to grips with). To blindly go in and up the settings +5 (or +7, whatever), WITHOUT actually going the whole route and installing ports on the header tubes, inserting EGA probes to take CO readings, etc, is somewhat problematic. Unless you can observe the carbon monoxide levels when you dick around making EFI changes... you're just guessing. True, we have generally found that increasing the settings about 5 or 7 digits on the LCD screen have generally helped out reducing the low-speed surging that many FJRs display. But, this is not always the case.... many have tried the Barabarian Mod with no perceived improvement.

2) I'll agree increasing the fuel pressure 5psi might aid in addressing some low-speed drivability issues such as the well-known 25-30mph FJR surging. But the fact of the matter is this: this is simply a flat pressure increase to the fuel rail by 5 psi. Nothing more. No "tuning" is occurring across various RPM ranges like a PC-III does. None whatsoever. Now, I trust Turbo City is not trying to represent that it does. But I also want forum members to be aware of that fact. With a PC-III, you are electronically tuning the EFI systems for optimum performance across the entire RPM range. If you need to alter the tuning based upon the addition of a exhaust system, or want a different fuel mapping for a particular need, you can do so via the buttons on the PC-III module or by downloading a different map.

But by installing a higher fuel pressure regulator, you're simply doing a flat 5psi increase to the fuel rail. That's it. And the thing is, it's higher at all times, under all conditions, with no ability for adjustment.

Mind you, I'm not trying to infer the higher fuel pressure regulator is evil, because it's not.

But it's definitely no Power Commander, either.

 

[tripletango]

Fuel pressure regulators can be calibrated to different pressures if you have the equipment. I am guessing this is the question.

No, that's not what I'm referring to....

It's alluding to the idea that this higher fuel pressure regulator, in conjunction with the Barbarian Mod, is a substitute for the Power Commander. That's hardly the case. For two main reasons:

1) While the Barbarian Jumper Mod has had a lot of press over the years, there are some aspects about it that many don't understand (or want to come to grips with). To blindly go in and up the settings +5 (or +7, whatever), WITHOUT actually going the whole route and installing ports on the header tubes, inserting EGA probes to take CO readings, etc, is somewhat problematic. Unless you can observe the carbon monoxide levels when you dick around making EFI changes... you're just guessing. True, we have generally found that increasing the settings about 5 or 7 digits on the LCD screen have generally helped out reducing the low-speed surging that many FJRs display. But, this is not always the case.... many have tried the Barabarian Mod with no perceived improvement.

2) I'll agree increasing the fuel pressure 5psi might aid in addressing some low-speed drivability issues such as the well-known 25-30mph FJR surging. But the fact of the matter is this: this is simply a flat pressure increase to the fuel rail by 5 psi. Nothing more. No "tuning" is occurring across various RPM ranges like a PC-III does. None whatsoever. Now, I trust Turbo City is not trying to represent that it does. But I also want forum members to be aware of that fact. With a PC-III, you are electronically tuning the EFI systems for optimum performance across the entire RPM range. If you need to alter the tuning based upon the addition of a exhaust system, or want a different fuel mapping for a particular need, you can do so via the buttons on the PC-III module or by downloading a different map.

But by installing a higher fuel pressure regulator, your simply doing a flat 5psi increase to the fuel rail. That's it. And the thing is, it's higher at all times, under all conditions, with no ability for adjustment.

Mind you, I'm not trying to infer the higher fuel pressure regulator is evil, because it's not.

But it's definitely no Power Commander, either.

Surely higher pressures are only required if fuel demand overwhelms the amount of fuel that the existing pump can provide. If you add 5 ibs and there is no additional demand what have you achieved?

 

[HaulinAshe]

Surely higher pressures are only required if fuel demand overwhelms the amount of fuel that the existing pump can provide. If you add 5 ibs and there is no additional demand what have you achieved?

Since fuel delivery is not a true square-wave function, but has some rather "rounded corners" during on/off transition, the increased fuel pressure would change the spray pattern during transitions, especially at higher RPM ranges.

Although IMHO TTT's doubt is well seated, as long as the existing pressure setting is sufficient at all ranges. But it does sound like someone may have found a slight deficiency in the stock pressure settings. I would think that is most likely to occur around 1/3 throttle where the injector pulses combine with pump pulsations to produce the most significant oscillations in static fuel pressure.

 

[drjfjr]

I agree that tuning using CO monitors would be best but unfortunately I do not have one and do not know any one who has one localy except for dealers. I continue to evaluate state of tune by looking at plugs until I can get equipment to otherwise help. The power commander is great if you go get it tuned as well. Unhooking the O2 sensor makes it open loop like carborators used to be IMHO. The power commander does not monitor actual emisions thus when conditions or fuel changes it does not adapt. I felt that keeping the O2 sensor and using a higher fuel pressure it would help in transitions and not effect steady state since the closed loop would take over with the ECM. I agree that the barbarian jumper just adding numbers is not the best but my plugs still do not show it is rich and drivability is better based on seat of the pants. The only way really tell is to put it on a Dyno. The closest one is in Lexington that I have heard about but I am not sure plus it is a matter of dollars.

I appreciate the communication on this board. Keep it coming because I am constantly learning.

 

[S76]

I would suspect the increased fuel pressure would be a welcome addition to an engine that was set up way to lean to even run right. We know why it's so lean, and that's fine. These engines are lean over the whole spectrum. Seems to me an increase in fuel pressure would make it a little richer over the whole spectrum. Sounds like a reasonable plan. As exact a map as a PCIII, probably not. But certainly not going to cost $300 either. It may be a good alternative for many. I am interested to see how it does.

Please keep us informed.

 

[jestal]

Resetting the fuel pressure regulator blindly adds a percentage of fuel across the entire operating range. This is a pretty medieval modification to a fuel injection system.

It has nothing to do with eliminating pressure pulsations or the "rounded off" areas of the injector flow. All that is taken into account by the production fuel injection system.

Basically a fuel injection system works by opening the injector for a calculated period of time and then closing it. Based on a constant fuel presssure drop across the injector tip the flow characteristics of the injector are known and plugged into the engine contoller calibration. Since the intake manifold vacuum is "sucking" on the injector tip and it is constantly changing the fuel pressure must also change constantly so as to have a constant pressure drop across the injector....i.e...the fuel pressure in the rail relative to the "pressure" in the intake manifold must always be constant. All the ideas of fuel pressure causing "leaness" or the injector open-close flow characteristics are included in the basic engine calibration laoded into the electronic controller. A very rudamentary rule of thumb is that the percentage of fuel pressure increase (in a case like this) is roughly equal to the percentage of fuel added. If the base fuel pressure is 50 PSI and the pressure regulator is jacked up 5 PSI you have just made the entire calibration (from idle to WOT) 10 % richer. This is a pretty gross "adjustment"....

While the FJR in various model years may be "lean" in spots I doubt seriously that it is lean at all at heavy and full throttle. From my own experiments with the PCIII and the reports of others dyno tuning with the PCIII I have never heard anyone claim to add any full throttle HP by adding fuel. Besides, with a high specific output engine like the FJR it would not live long at all at full throttle if it were "lean". Adding fuel at full throttle would be the last thing I would recommend, actually.

While the jacked up FPR might help with some of the lean surges off idle reported it will be at the expense of poorer fuel economy and overall rich operation across the rest of the operating spectrum. If you do not disconnect the O2 when doing this the system will spend all it's time while in close loop operation trying to "learn" the extra fuel out anyway which could lead to some poor driveability later as it has tried to compensate for the added fuel.

If you are thinking of this mod simply disconnect the O2 sensor first to force the system into full time open loop operation and see if that will help the driveablity complaints. You'll have to do it anyway if you jack with the fuel pressure regulator setting so try just the O2 disconnet first.

It would sound a lot more palitable to me to add just 1 or 2 PSI to the fuel pressure regulator setting not a jump of 5. That sounds a bit crude..... Sort of like running with the choke on all the time....

 

[HaulinAshe]

If you do not disconnect the O2 when doing this the system will spend all it's time while in close loop operation trying to "learn" the extra fuel out anyway which could lead to some poor driveability later as it has tried to compensate for the added fuel.

Jestal, wouldn't the system typically compensate (learn) away the 5 psi increase, eventually resulting in the same mixture? Or would that be out of range for the system resulting in an overall richer setting?

I didn't see any mention of disconnecting the 02 sensor in the start of this post. So it makes sense that initial testing after the FPR change may seem positive, while later on yielding a very different result. This could also be a real problem for bikes operated at higher altitudes if the software reaches some hard coded limits.

 

[BrunDog]

Yeah, gotta got with the previous comments. Hamfisting more pressure on the rail is crude. You should only do this if you can't get enough fuel into the engine with the stock injectors, say when turbo or supercharging.

Besides, I would believe the the O2 sensor will sense the richened gas, and the ECU will lean it down for those periods (albeit brief) when the system is running closed loop.

If you want to tune it right, get a PCIII and stop using using a crowbar to tune a piano.

-BD

 

[twowheelnut]

... and stop using using a crowbar to tune a piano.

If you've ever been to a children's' piano recital, a crow bar would have improved the noise.

 

[Warchild]

If you want to tune it right, get a PCIII and stop using using a crowbar to tune a piano.

Excellent....

 

[05fjrBluedevil]

keep testing, let us know how it goes.

It great when more than a few test things for us!

 

[turbocity tom]

Good morning to everyone,

Let me try to answer some of the questions about the fuel pressure regulator.

We are in the process of developing the proper pressure on the modified FJR regulator. I need several riders to test the product and report back to me the results. I will provide a modified regulator free of charge. The installation is very easy and there is no chance of engine damage in the ranges that we use.

I currently do this modification for the Honda ST1300, CBR1100, VFR800, VTX1800,and the GL1800. The process is well proven and the results are very good.

In most applications it eliminates the need for a PCIII as the drivablity is greatly improved. This is NOT designed as a performance modification but many report better power. Many also report better fuel ecconomy once they return to their normal driving style.

The EFI systems on the bikes are very simple systems. They are tuned very lean to pass emissions tests. This is where the drivablity issues come from. You have to believe that the engineers of these systems did not leave much additional power to be created. All EFI systems have limits to the amount of corrections that they can make to a fuel curve, otherwise you could make any changes that you wanted and drive it long enough for it to make the changes and make it drive perfectly.

What I do is shift the fuel tables up very slightly. It is still within the limits of what the computer wants to see, so there is no problem with the "FI" light. The change in fuel pressure is minimal and typically effects the low to mid range more than the top end. The O2 sensor remain connected as you want the computer to continue to function properly.

This is just another way to help make our bikes run better.

The target market price will be around $130.00.

Sorry, it will not work on the 06 as they changed the fuel system.

If any one is interested let me know. Thanks Tom