Audace stumbles on WOT

[toomanybikes]

I've recently experienced some strange and intermittent fueling behavior.

When the tank is relatively low, like three bars or less, the engine will momentarily bog down under sudden heavy throttle, almost like it was running out of gas, but the tank was not empty.  Gradually rolling on the throttle is fine. Filling the tank resolves the problem, but it's not yet clear if it's a fuel level thing or just relieving built up pressure due to clogged vents. The vent tubes all seem to be in place, but I have not yet removed the tank to see what lies beneath.

The bike was a rescue after sitting for unknown years. The tank does not have any sludge in it, but the filter and pump are probably the original.
I'll plan to empty the tank and replace the filter, but should I look for anything else? The pump seems to work fine, except the weird fueling at low levels.

The bike has the stock airbox. I replaced an airbox hackjob by some previous owner. there are no indications of flashes or mods.

It *probably* still has the fuel vapor recovery system in place since I can see the pressure valve attached to the vent tube coming from the fuel opening. It's possible someone messed with that system, given other mods that were done and indications that someone took the tank off previously.

The fuel cap flange spacer is in place with a tiny opening near the vent barb. See pic.

Any suggestions beyond "open the cap perdiocially"? That's one likely easy fix, but I'd rather understand and fix the underlying issue.

[Moparnut72]

Having owned an Audace I would check the filter first thing. The evaporative system is pretty benign so I doubt any mod to it will help one way or another. I did mine as recommended by a well known shop owner. It didn't make the slightest improvement in the low gear low rpm surging. During the time I had the bike Beetle wasn't releasing his map for it due to an issue. He has one now.
kk

[toomanybikes]

Having owned an Audace I would check the filter first thing. The evaporative system is pretty benign so I doubt any mod to it will help one way or another. I did mine as recommended by a well known shop owner. It didn't make the slightest improvement in the low gear low rpm surging. During the time I had the bike Beetle wasn't releasing his map for it due to an issue. He has one now.
kk

Thanks. Here's a pic of the pump/filter assembly. Any input on if the hoses can be re-used? I know the oetiker clamps are one and done.

The evap system seems to be in place, tucked in behind the starter motor, with at least the primary hose still connected. A few of the other lines were left unattached, although one is probably for the fuel tank vent line not the evap system.

[Moparnut72]

I bought mine kind of used, 500 miles, from a dealer repo'd due to a fraudulent credit ap.  It had originally spent 3 years on the dealer's floor. When it was being checked for me it dropped a valve at least that is what I guess from what I was told happened on a test ride. I had the tank off for another mod and found that the tank vent hose wasn't connected to anything. I think the mechanic who replaced the engine left it this way. I really liked mine but selling it was the start of my downsizing due to age, it was a handful to ride at walking speeds. It was a major mile muncher.
kk

[TN Mark]

Does your tank make the moaning whale sound? If so, you likely found part of your issue. Also, on the riders right hand side of the intake plenum is a vent that goes from the charcoal canister to the intake. That connection can sometimes be less than hand tight. It’s best to remove that and put a bolt in the plenum instead.

If you do an internet search on moaning whale Moto Guzzi 1400 and tip over valve remedy, you will very likely find the solutions to your issues. The Tip Over valve is often a particular source of frustration on the 1400s. I gutted mine recently following the instructions to the T.

Also, if you have the 2016 and earlier firmware in the ECU, that was also quite poor. If going to a dealer is an option to get the latest 2017 firmware downloaded into the ECU that may also work. The ECU on the 1400’s was specifically designed not to receive aftermarket downloads. The last thing you’d want is to brick the ECU.

Also, your fuel filter is the hood type. Some of the earlier ones were half metal and half plastic that was sure to deform. If you haven’t yet, pouring a can of Seafoam in the tank and running it through is also a very good idea.

But confirming the mechanical issues are solid is your first coarse of action.

[toomanybikes]

Does your tank make the moaning whale sound? If so, you likely found part of your issue. Also, on the riders right hand side of the intake plenum is a vent that goes from the charcoal canister to the intake. That connection can sometimes be less than hand tight. It’s best to remove that and put a bolt in the plenum instead.

If you do an internet search on moaning whale Moto Guzzi 1400 and tip over valve remedy, you will very likely find the solutions to your issues. The Tip Over valve is often a particular source of frustration on the 1400s. I gutted mine recently following the instructions to the T.

Also, if you have the 2016 and earlier firmware in the ECU, that was also quite poor. If going to a dealer is an option to get the latest 2017 firmware downloaded into the ECU that may also work. The ECU on the 1400’s was specifically designed not to receive aftermarket downloads. The last thing you’d want is to brick the ECU.

Also, your fuel filter is the hood type. Some of the earlier ones were half metal and half plastic that was sure to deform. If you haven’t yet, pouring a can of Seafoam in the tank and running it through is also a very good idea.

But confirming the mechanical issues are solid is your first coarse of action.

I haven't heard any moaning whales, so I won't go down that thread. The nearest guzzi dealer is 2 hours away via the slab, so I'll leave the ECU alone for now.

I've replaced the filter (see pic, oddly I had the correct one on hand), so will try that and investigate the plenum item you mention.

[bmc5733946]

I don't believe that spring clamps are up to the task of a high pressure pump, about 40psi if memory serves. I am willing to be corrected. I always use little rolled edge eared clamps rated for fuel injection.

Brian

[toomanybikes]

I don't believe that spring clamps are up to the task of a high pressure pump, about 40psi if memory serves. I am willing to be corrected. I always use little rolled edge eared clamps rated for fuel injection.

Brian

I've heard varying info on that area and didn't have any oetiker (ear) clamps on hand. Oddly, the local auto parts stores didn't have any on hand and Amazon's were all next day ... except the size I needed (8.8-10.5mm). They guys at the local hose fitting store didn't have any ear clamps that small and thought the green ones would be fine for 40psi. I'll do a test start with a gallon or so of gas.

[bmc5733946]

Eared clamps like these.

https://www.napaonline.com/en/p/BK_7051226?srsltid=AfmBOopRFyqcU2GOPNTubAQDq2jWG_k4PIu61iLBReWSCM11ARM6bKuVbRw

Or here.
https://www.amazon.com/Fuel-Injection-CLAMP-Clamps-30PCS/dp/B07T29HV4L

Brian

[toomanybikes]

Or here.
https://www.amazon.com/Fuel-Injection-CLAMP-Clamps-30PCS/dp/B07T29HV4L

Brian

I ordered the amazon option to have on hand. I'll keep an eye on the spring clamps. Now that I have experience removing the tank and pump, it will be pretty easy to do a second time if (hopefully not) needed.

[bmc5733946]

It's not the pump/filter removal process that irritates me. It's the fuel removal, tank removal, and external line removal that irritate me the most, after all that it's a piece of cake.

Brian
 

[toomanybikes]

It's not the pump/filter removal process that irritates me. It's the fuel removal, tank removal, and external line removal that irritate me the most, after all that it's a piece of cake.

Brian
 

Have you ever tried getting the tank out of an '80's Honda GL1100 (Goldwing)? The Audace is a walk in the park.

[TN Mark]

I thought removing the tank on my Eldorado 1400 was a breeze.
Instead of disconnecting the fuel line at the base of the pump, there’s another disconnect (black connector with square green releases) along the RH frame rail that makes that an easy, low risk endeavor.
Also, removing the top decorative valve covers eases tank removal and minimizes the risk of scratching anything.

I don’t know if I’m allowed to mention the ‘other’ Guzzi forum here or not. They’re a ‘Technical Guzzi’ forum, not a social type forum for shooting the breeze or submitting ride reports etc. That being said, any running, suspension and How To question you may have on a Moto Guzzi is very well covered. Mostly with step by step posts with pictures. I’ve learned a great deal about the 1400s over the years by being a member their.

I highly recommend that site for the Do It Yourself type that wants to learn not only what causes there issue(s), but how and why to properly solve it.

I’m TN Mark over their as well.

[toomanybikes]

I thought removing the tank on my Eldorado 1400 was a breeze.
Instead of disconnecting the fuel line at the base of the pump, there’s another disconnect (black connector with square green releases) along the RH frame rail that makes that an easy, low risk endeavor.
Also, removing the top decorative valve covers eases tank removal and minimizes the risk of scratching anything.

I don’t know if I’m allowed to mention the ‘other’ Guzzi forum here or not. They’re a ‘Technical Guzzi’ forum, not a social type forum for shooting the breeze or submitting ride reports etc. That being said, any running, suspension and How To question you may have on a Moto Guzzi is very well covered. Mostly with step by step posts with pictures. I’ve learned a great deal about the 1400s over the years by being a member their.

I highly recommend that site for the Do It Yourself type that wants to learn not only what causes there issue(s), but how and why to properly solve it.

I’m TN Mark over their as well.

Agreed on removing the tank, especially the fuel connector, but I didn't bother with the valve covers.

I'm on the "other site" as well, but am sometimes confused by what types of questions are allowed. Some of my posts, that I thought were reasonable technical questions, have been removed as violating forum rules.

[Frulk]

MoparNut….

Remember this bike?





My opinion only. Best looking bike at Broken Arrow that year.

[Moparnut72]

Sure do. I miss that bike a lot. It would eat miles like crazy. It just got too awkward for me. Being 700 lbs with 6.1" of trail and 32* headstock angle did not contribute to confident parking lot handling, u turns were almost terrifying. A younger bigger kind of guy would be the perfect rider. The MGX which is an Audace with fairing, stereo with all the extra weight would be beyond a regular rider's ability. I once started to lift one off the side stand in the dealership, I didn't finish.
kk

[TN Mark]

Of course I admit to being biased but: the Eldorado is the ‘best’ of the 1400 line.

Then the Audace and the standard California. To me, the California Touring bags are way too wide and the front wheel geometry on the MGX-21 didn’t work for me in the showroom.

I’m still bummed the 1400 line was killed in 2020. Though YouTube has no shortage of AI generated videos of the 2025 and 2026 1400 bikes.

[Moparnut72]

I test rode an Eldorado and in hind sight I wish I had gotten one of those instead. With the smaller front wheel diameter it probably would have allowed me to ride it longer than the Audace.
kk