1995 Yamaha 85 is burning more fuel then usual?

[Mike_Berry]

My Yamaha has 1200 hrs and runs great but lately my fuel consumption went from a average of 3.23 KMPG to 2.76. I do a lot of trolling at 2000-2100rpm.

1st I did a compression check and it's 112,111,111. 100 hr hours ago it was 115,115,115. Could this cause a higher fuel burn?
2nd I thought maybe the thermostat had a problem and it was running cool. I checked the thermostat housing and head while on the hose and it was 100 degrees. The sat is 122 degrees. Should it run warmer at idle on the muff? I'm in he middle of changing it and hope it runs warmer and more efficient.

What do you guys think?

 

[Mike_Berry]

I had a bunch of responses but don't know where they went. Anyway I replaced the thermostat and fuel pump. It runs at 115 degrees on the thermostat housing. My fuel mileage is back to normal. 3.4-3.5 kmpg. She's running great.

 

[Yahman]

Glad you got it solved Mike, it's good you carefully monitored your fuel mpg so you know when it's off. I have no idea what mileage I'm getting, but perhaps in my case ignorance is bliss. Andy

 

[wn6ngp]

I had similar problem on my merc 90hp elpto. I wan't tracking fuel usage but what would happen is that if I slowed down to idle it wanted to stall and then hard to start. The thermostat was partially stuck open so at low speed in cool water it got too cool to run reliably.