• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

Thoughts on fuel pressure and lean condition

NPS

Cruisin' Guzzisti
GT Contributor
Joined
Dec 11, 2008
Messages
262
Location
Churchdown, Gloucester, UK
Today the fuel condition suddenly changed on my Breva 11. I have an air fuel ratio meter on the bike linked to a wide band so I was able to see a different AFR and a loss of power.

The problem was the usual 13.5 to 15 AFR suddenly changed to 15.5 to 16.5 range at any engine speed and throttle opening above 1800 rpm.

When I removed the fuel tank, I noticed that fuel continues to run from the red pipe without stopping. I have only had a few dribbles before so this has changed. I'm wondering if a valve has failed and this is reducing the fuel pressure. The pump sounds the same.

Any thoughts anyone?
 
Fuel should not run from that connector when disconnected, so you do have a problem somewhere. Pull the pump unit out and check.
And then change the fuel filter for an all metal one if it still has the half plastic version.
 
After what Brian has suggested, find a location to connect a pressure gauge. The fuel system pressure should be about 3 bar or 45 psi. If pressure is less then it is time to replace the fuel pump unit.
 
Bike that age I would think a crack in manifold rubbers or in stepper lines to TB's would be first to look for lean condition.
I get fuel from line but it usually stops at sometime. I would think the built in pressure regulator on the base plate would shut it off w/o pressure coming from pump. I thought some of those are replaceable.
 
Got the bike running sweet by temporarily adjusting the ECU Fuel-temperature table by +10%. Makes the bike run better than I have ever known. But I realise a failing fuel pump or valve is something I must checkout and will when the fuel level gets lower in the tank. Thank you Brian, Steve and John for your comments. The rubbers should be fine as I replaced the manifolds last year and the stepper motor tubes are ok on visual inspection.
 
Back
Top