My Guzzi is drinking stupid amounts of petrol

[pete roper]

My first thought was temp sensor too. While replacing the mout with a brass one is a good idea you can achieve the same result by simply packing the plastic one, carefully, with some sort of conductive paste and then slowly screwing the sensor back in. Slowly to allow any air to escape as if you screw it in quickly it is quite easy to crack the housing through hydraulic pressure.

 

The big problem here is that the previous owner has stuffed around comprehensively with the entire wiring loom. Who knows what they may or may not of done?

 

An obvious first step is to check that ALL the sensors are working and working correctly. Check the resistances and then the connectors and connections.

 

One good piece of news is that you can forget the 'Choke' as being a contributor to the issue. All the 'Choke' is is a fast idle lever that cams open the throttle plates a bit to help overcome the internal friction of the cold, thick, oil in the bearings on start up.

 

The spigot on the fuel pressure valve has been covered but note that this is on the tank, not the engine.

 

Pete

[Guest frankdugo]

just a thought, but the longer we have these bikes our overall average speed goes up.having said that thanks again pete for the sensor tip.seems to be using less&i've also given my right wrist a stern talking to.

[cycdude6]

Shoot, this thread has me wondering now...I'm getting 35 mpg with a power commander. My temp sending unit is brass, screwed into a black plastic adapter. Should I change out this adapter?

John

[badmotogoozer]

No, but you should take the sensor out of the housing and apply a bit of thermal compound (or anti-seize compound) to the tip and screw it back in. It doesn't sound like you have a problem.

[cycdude6]

No, but you should take the sensor out of the housing and apply a bit of thermal compound (or anti-seize compound) to the tip and screw it back in. It doesn't sound like you have a problem.

 

 

Thanks, I found some thermal paste at a computer store. WARNING!!! I tried to remove the plastic adapter first but it felt weird, like it was going to snap off if I added any more pressure so I ceased that and just removed the temperature sending unit, covered it in thermal paste and back in she went. I did not remove the tank, just removed the bolt and propped it in place. Now we find out if there is any improvement....

[pete roper]

You can get thermal paste at computer shops apparently as its used in various applications by nerds .

 

I simply use zinc based anti seize although copper based ones like 'Copperkote' will do just as well. Thier whole purpose is simply to fill the air gap and help heat transfer to the sensor, there's nothing clever about it. Olive oil or ordinary grease would probably work just as well but would need checking and replenishing more often. the *stuff* with copper or zinc in it simply has more solids and may *bake* itself into a useful heat transmitting plug. Thats my theory anyway and I'm sticking to it.

 

The main thing is to be very careful removing the sensor. The horrid plastic mount it is screwed in to is fairly fragile and may break, esecially if it is old and has hardened through heat cycling. I have yet to break one but I'm always waiting for it to happen! If it does I'd reommend replacement with the brass part but add some gloop to that too. With the plastic one once the gloop is in wind the sensor back in slowly and in steps to allow and air or excess gloop to creep out past the threads or there is a chance that the plastic mount will crack as the gloop tries to expand. I've never had this happen either but it is a possibility.

 

Readings taken from my Axone show that the 'Before' and 'After' temperatures being detected can vary enormously. 40*C is not uncommon. More than enough to make a joke of the fuel supply.

 

Pete

[gstallons]

Any sensor that has two wires in the connector does NOT need to be grounded. Air and coolant temp. sensors are temp.variable sensors. These sensors use two wires to transmit this info to the computer. The engine computer reads the resistance to comprehend the temp. of that particular sensor.

[cycdude6]

Got the paste in fine, no more issues and no improvement in gas mileage. Prior to thermal paste -- 37.5 mpg, after thermal paste, 37.7 mpg (100 miles, varied pace, both times). While it can't hurt, the fix probably only works on bikes with much worse fuel mileage caused by improper temperature sensing. My goal is to reach an average of 42 mpg -- hey a man can dream, can't he?

John

[dlaing]

WARNING!!! I tried to remove the plastic adapter first but it felt weird, like it was going to snap off if I added any more pressure so I ceased that and ...

Smart move!

The plastic adapter broke on me under what was probably less than 5 foot pounds of torque.

[Skeeve]

Got the paste in fine, no more issues and no improvement in gas mileage. Prior to thermal paste -- 37.5 mpg, after thermal paste, 37.7 mpg (100 miles, varied pace, both times). While it can't hurt, the fix probably only works on bikes with much worse fuel mileage caused by improper temperature sensing. My goal is to reach an average of 42 mpg -- hey a man can dream, can't he?

John

 

Test the sensor? Maybe you got a duff one...

[il_cacciatore]

My dealer says to replace the sensor housing is "hocus pocus bull shit" and must be something electrical so i've booked it into have a diagnosis done. To be fair, the oem part cant be so rubbish in order to make it run rich, surely guzzi have put enough thought when designing to have the correct parts... or have they??? I dont know what to think any more.

[slug]

To be fair, the oem part cant be so rubbish in order to make it run rich, surely guzzi have put enough thought when designing to have the correct parts...

 

[raz]

[Dan M]

If the ECU doesn't use the temp sensor's data to determine mixture then what is its function?

Enlighten us please.

[il_cacciatore]

Of course the temperature sensor's function to the ECU is to enable determination of fuel/air mixture ratio but what I'm saying is the plastic housing must be of the correct material for the job to conduct heat to the temperature sensor because if it needed a brass housing to make the bike run correctly then surely that's what the oem part would have been and not the plastic one fitted if the plastic material is not capable of conducting the heat to the sensor itself. I realise that its like everything else that costs need to be cut in some places to enable healthy profit margins and value but if this part is critical to the overall well being and running of the bike then surely they would have used a brass part instead of the plastic one that is fitted? If the temp sensor is broken itself then that's a different issue surely? I'm just theorising here and not challenging anyone view or opinion that has been kind enough to lend me some advice as my knowledge of the Guzzi engine isn't substantial enough in order for me to come to logical sound conclusions on these matters.