2001 MG California Special

[Dimi Pana]

Hello all, I hope everybody is well, staying healthy and sane.

I need advice on what the pressure regulator is (what it does) and how it's supposed to work while attached to the tank. Is there a way to test if it is working as intended? I recently decided to freshen up the paint/finish on my bike so I removed everything including the tank. Then when I put everything back together the pump would make a whining noise when pressurizing and running (see below). So I disassembled (again) the tank and while troubleshooting I noticed that with the fuel pressure regulator connected to its hose but not attached to the tank, the pump noise is gone?!

Initially, I though that my pump went bad because recently I had to de-rust the tank after the bike sat for long in a humid garage. But how much rust made it thru the petcock mesh and how much rust is enough to damage the pump or clog the filter down the line I do not know. My theory was that if fuel is restricted thru the fuel line system (petcock, pump, filter, etc) then the pump will ..."whine" because it is has to push harder, right? The only unknown to me in this equation is the role of the pressure regulator.

I am hoping the noise was due to an improperly routed fuel pressure hose which might have caused a restriction?! I have no clue, please chime in! Thank you!

I'm sharing the tinyurl link below, it will take you to my Google Drive Public folder:

tinyurl.com/3jbhtcsc

There you can find:

1. A schematic of the fuel system; I am talking about items #15 and 17 to #21.

2. Two audio files: The titles are self explanatory; One is with "ignition key ON, engine RUN switch ON" you can hear the pump pressurizing and making the noise at the end. The other one is with the engine running. The clicks you hear are turning the ignition key and switching engine RUN on and off.

Thank you all so very much!

 

[john zibell]

The external fuel pump does whine. That is normal. If you must see if the pressure regulator is doing it's job, rig up a T fitting with a pressure gauge and connect it at the output of the fuel pump and to the line going to the fuel filter. With everything connected, you should have approximately 45 psi of fuel pressure. If it is higher, then the regulator would be suspect, or the fuel filter is clogged.

 

[Dimi Pana]

Thanks John, yes it whines but now it's a bit louder than before. Did you have a chance to listen to the sound bites? Something is restricting flow. I will try to rig up what you said, not easy though as everything is so cramped in there, I'd have to disassemble a lot before I can do that. I am also suspecting a bad petcock. I wanted to get the manual one from MG Cycles that you suggested in another thread but it is currently on back order. If it is the electric petcock (plunger not retracting) it could cause the pump to overwork (thus whine more), correct? Last question, I read somewhere with the manual petcock you can leave it ON all the time and it won't cause problems, but for long storage it's advisable to turn fuel OFF. Is this correct? IF yes, and IF I find mine is faulty, I could just ...hack it (i.e. cut the plunger) and make it always open, 'till I get a replacement. Do you agree with this workaround so I can still use the bike? Thank you so much!

 

[john zibell]

If the electric petcock isn't opening that would overwork the fuel pump. The only time I ever turned the manual petcock off was when I needed to remove the fuel tank. Not sure if you could open up the electronic petcock. You could cause more problems than you solved. You might see if Harper's has a manual petcock available. With their inventory, if not new, a good used one.

 

[Vagrant]

Do you hear the petcock clunk open, then the whir of the pump when you first turn on the key after setting some. The petcock is on a separate fuse and the pump will push past it and the bike will run with it closed. If you do then I'd check the screen in it, then replace the fuel filter again.

 

[Dimi Pana]

Thank you for your replies.

I couldn't be sure whether the petcock did clunk open. So, I removed and disassembled it (see photos). When I turn the ignition ON the plunger (with black O-ring) does not retract and there is no click or other noise from the petcock mechanism. Then I disconnected the petcock from its harness and applied power directly from the bike's battery. Guess what!? It worked fine! The plunger retracts and the elusive clunk is finally there! So the petcock works as it should. Then, I measured the power leads coming from the harness with petcock removed. As soon as I turn the ignition ON I have 11.5 V dc. Now my battery is brand new and fully charged at 12.8 V dc. Perhaps the 1.3 V dc difference is justified because the engine is not running and a bunch of lights plus the ECU, etc, are now ON. But then I measured the voltage actually reaching the petcock, at its two leads (see in photo #4). What!?! ONLY 2.36 V dc. Somehow, the bike's circuitry when petcock is connected does not provide enough voltage for the plunger to operate (?!). Perhaps because the electric coil that retracts the plunger is presenting a larger than nominal impedance hence the huge voltage drop, I do not know. Btw, I measured across the petcock leads, I read 34.6 Ω resistance (no clue if that's right or not). I honestly do not know what's going on, I have also attached the electrical schematic in case you want to trouble shoot (John you posted that in another thread, so the credit goes all to you!)

Btw, now that the tank is off, pressure regulator not attached to tank, fuel level sensor and petcock not attached/connected, if I turn ignition ON and then switch the engine RUN to ON, I hear the pump energize but with-OUT the funny whining noise. Of course I can't run the engine like that, but I am almost sure the original pump noise problem was due to the petcock not being energized (not because it is faulty but because SOMEHOW it is not receiving enough power).

Looks like my BEST bet is to find a manual petcock and until I get that, I have to come up with a way to modify the existing petcock from electric to manual. What's your take about all this? Kinda interesting, right?! Thanks!

 

[john zibell]

Looking at the schematic, you should be getting full voltage. If you are getting that much voltage drop I'm betting on corroded or dirty connectors. I'd start by checking the safety relay, item 36 on the schematic. If you upgrade your account, you can get the schematic in the downloads which can be enlarged significantly for easier reading. https://www.guzzitech.com/forums/threads/user-account-upgrade-donations.14025/

 

[Vagrant]

I suspect you, like many others have reversed the power leads for the petcock and the fuel gauge. It's a poor set up and most likely you have fried the sensor for the fuel gauge sending 12 volts to it. Put the 12 on the petcock and the other on the sensor. Good luck.

 

[john zibell]

I suspect you, like many others have reversed the power leads for the petcock and the fuel gauge. It's a poor set up and most likely you have fried the sensor for the fuel gauge sending 12 volts to it. Put the 12 on the petcock and the other on the sensor. Good luck.

Good possibility. The one for the petcock has a red band on the cable.

 

[Dimi Pana]

I suspect you, like many others have reversed the power leads for the petcock and the fuel gauge. It's a poor set up and most likely you have fried the sensor for the fuel gauge sending 12 volts to it. Put the 12 on the petcock and the other on the sensor. Good luck.

 

[Dimi Pana]

I agree 100%, these two power leads can be easily confused if you're not observant enough during disassembly. But I did notice the red band as John pointed out around the Petcock lead; still once you remove it, there's no indication which one is which, as the Red band stays with the Petcock lead not with the one coming from the harness. Just to be on the safe side, when I put it back I measured both what voltage I'm getting. Petcock lead should be an obvious 12 volt DC or so while the lead to the fuel sensor should show no voltage at all or very little voltage. Btw, I never pay attention to the clunky dashboard fuel light, I always go by mileage. By the way I did find the manual petcock at Harper's; it's 55 dollars ($15 more than mg cycles) plus shipping but at least they have it. And just for laughs they're selling the electric one for ...$153.68 ... UNBELIEVABLE !!! Thank you both for your feedback.

 

[john zibell]

I agree 100%, these two power leads can be easily confused if you're not observant enough during disassembly. But I did notice the red band as John pointed out around the Petcock lead; still once you remove it, there's no indication which one is which, as the Red band stays with the Petcock lead not with the one coming from the harness. Just to be on the safe side, when I put it back I measured both what voltage I'm getting. Petcock lead should be an obvious 12 volt DC or so while the lead to the fuel sensor should show no voltage at all or very little voltage. Btw, I never pay attention to the clunky dashboard fuel light, I always go by mileage. By the way I did find the manual petcock at Harper's; it's 55 dollars ($15 more than mg cycles) plus shipping but at least they have it. And just for laughs they're selling the electric one for ...$153.68 ... UNBELIEVABLE !!! Thank you both for your feedback.

If you look further up the cable, the bike harness should have the red band. If it isn't there I guess someone removed it. Good that you have the manual petcock on the way.

 

[Dimi Pana]

You are 100% correct John, the red band is missing on the harness side, and when I asked the previous owner he did admit that his mechanic had to do some ...rerouting while fixing ..."something". Btw, and not that I doubted your opinion, I confirmed from a trusted mechanic that EFI bikes with inline fuel pumps do NOT need an ON/OFF petcock. You can route your fuel line directly from the tank to the fuel pump which turns on and off as needed, effectively functioning as a petcock. I really wonder why Moto Guzzi complicated things so much by introducing a totally unnecessary and malfunction prone electric such.

I haven't ordered the manual petcock yet, and most likely I will, but for now I am trying to modify the upper half of the electric petcock, while eliminating the lower electric portion. I could easily put some epoxy there but I want the mod to be reversible. Hey it's Saturday I have time let's see what I come up with I'll post pictures soon.

Thank you all for the support!

 

[Dimi Pana]

By the way I received a message from a forum administrator that internet links especially those pointing to personal folders are not permitted plus they usually never work. I apologize for my ignorance and I am attaching (the pump whining noise) audio files in MP3s but zipped as required per forum rules. Sorry and thanks again!

 

[john zibell]

You can route your fuel line directly from the tank to the fuel pump which turns on and off as needed, effectively functioning as a petcock. I really wonder why Moto Guzzi complicated things so much by introducing a totally unnecessary and malfunction prone electric such.

So that when you remove the fuel tank you don't have gas running everywhere. I wish they had stayed with the manual petcock. Those are pretty much trouble free.

 

[Dimi Pana]

Of course, I was not clear before, the petcock is necessary when removing the tank, I was just wondering why MG opted for a design that -for the intended purpose- is over-engineered and prone to failure.

Btw, was able to find a quick and dirty way to plug the the bottom of the petcock's top part thus making it (temporarily) an always ON "petcock". Now the manual one from MG Cycles or Harper's or whatever can come anytime. I wanted a proper solution that can be reversed if needed. I measured the inside threads at 8 mm x 1.00 pitch which after some searching at my local Menards was able to find. A drop of blue loctite, a rubber bushing/washer and fuel has nowhere to leak (I hope). I admit, it's a hack but this way I'm not missing riding with my buddies tomorrow, plus I got a great story to tell (I also think it looks ...great ).

Now, what's causing the electrical failure, the petcock mechanism or -likely- the bike's harness (corroded leads as John said) that 'll have to wait.

Btw, did anyone try to listen to the sound of the pump? What'd you think?!

 

[Vagrant]

Sounds like the valve is clicking open right, but the pump is very noisy like it is having trouble pushing the gas through. That or it's now worn out from the valve not previously working. Also it should run longer before going on than it now sounds. Restriction somewhere?

 

[john zibell]

Sounds like the valve is clicking open right, but the pump is very noisy like it is having trouble pushing the gas through. That or it's now worn out from the valve not previously working. Also it should run longer before going on than it now sounds. Restriction somewhere?

I think the click you hear is the ignitions switch. The duration is OK.

 

[Nick Cali]

Hi, listening to your pump-files. To my experience (1100i, same engine and lay-out) its way to noisy.
Replacing it can be done at low cost if you buy a Bosch pump of Magnetti Marelli pump via carparts stores.

The electronic petcock, as far as I know it is the most commonly early replacements by Guzzi-owners who were so
lucky to buy a bike with that contraption; the majority opt for manual.

 

[Dimi Pana]

Thank you all for the feedback. Indeed the pump is noisy. However, so far, troubleshooting revealed the following facts:

i) The electric petcock will open if supplied with 12Vdc directly from the battery, but will not work when connected to the bike's harness (it should make the "clunk" sound when turning the ignition key to ON, while the 'engine RUN' switch position is irrelevant)

ii) With ignition ON but engine not running, the voltage available at the harness connector (with petcock lead NOT connected) is about 1.3 Vdc lower than the bike's battery (12.8 Vdc), but even that should be enough to operate the petcock (I checked with different voltages, and it opens with as low as 7.5 Vdc)

iii) However, once the petcock's AMP plug is connected to the harness, the voltage actually getting at the petcock's two leads is a VERY low 2.36 Vdc (?!?). I am not an electrical engineer, but as John suggested, the culprit could be the circuit feeding the petcock; e.g. corroded leads, frayed wiring, something wrong with the relay, etc.

So I modified the top part of the electric petcock, I unscrewed the lower (plunger, coil) part and plugged the resulting hole (as seen in the pic in previous comment). So now fuel will run freely from tank to the fuel pump and if the noise is still there, obviously we know what's wrong.

Another thing I do not know is, IF the hose (from the fuel filter to the pressure regulator) is improperly routed (i.e. restricted), would that cause the pump to over work?! And of course the fuel filter (if fouled) can be another source of restriction, although that cannot happen from one moment to the other. The pump (excessive) whining started after I removed and reinstalled the tank in order to do some maintenance (clean it, fix a weeping seam, repaint, etc.). Of course the petcock going bad from one moment to the other is rather strange also, but again, based on everyone's info so far, a petcock CAN and WILL go bad without warning, while a fuel filter getting clogged should be a more gradual process. Again, I am providing you the facts, based on careful observation and tests. I have no idea how I got into this mess.

I was hoping yesterday to put everything back together (with the modded petcock) and ride with my buddies, as we usually do on Sundays. But the weather was crummy (constant rain, thunderstorms) in my area (NW suburbs, ~30 miles from downtown Chicago) so I decided to not rush the ..."project". I will do some more testing and "digging" today; see if and what I come up with.

* In the mean time, and while the tank is still OFF, I decided to apply a vinyl/rubber trim to protect its edge (see pic below). I had previously ordered it from MG Cycle, it comes (not cheap) at ~$10 per 1 meter (!) and (per Matt, or Gordon, or Rick or Andrew at MGC) its groove was supposed to be wide and tall enough to fit securely over the tank's edge. Well, it is not. So I definitely need some sort of adhesive to help it stick and not come off. Has anyone of you done this before? What did you use? Plain glue, clear silicone adhesive, what?! The idea is, it has to be sticky but not permanent in case the trim need to be removed.

Thank you all again for taking the time to read my Qs and provide answers. It is very much appreciated!