Engine runs fine on muffs not in water

"friend took out his boat with

"friend took out his boat with a 76 135 evinrude. the things runs good on muffs but not in the water. its almost like the idle adjustment goes way down when its in the water. says it wont idle, only when hes got the high idle wide open and wont move while in gear, but you can see the prop spinning while in gear, both ways"

"Sounds like it may not be run

"Sounds like it may not be running on all cylinders or the compression is low. Good place to start, Check spark on all cylinders and/or then check the cylinder compression."

"Thanks plugs are a little fou

"Thanks plugs are a little fouled so were gonna try that first. Then we check spark and compression. Well let you know, thanks.

We also tried running it in water tonight and yeah, when you give it throttle it just bogs and stalls."

Time to clean the carbs. Speci

Time to clean the carbs. Specifically the idle jets/idle circuit. You can just about do that with the carbs on the motor if you want to take a huge shortcut. Spin off the idle circuit passage screws on the side of the carbs and use a rubber tipped air hose nozzle and with about 25 PSI blow into the brass jet that is under that screw cover. Don't remove the jet with the carbs on the motor though as they are small and easy to drop. Next move on to the main jets in the bottom of the float bowl. Unscrew the large screws in the bottom side of the float bowl and remove the large jet from there and blow it out. Be careful of the head on the brass jet though. I had one off a set I did that was completely blocked.

Remember very little fuel is needed to get the motor to idle on the muffs. But once you are in the water you need a lot of fuel to get the engine speed up.

I had a stick float back in July that was similar to this. Without fuel in both carbs I could not get more than 2200 RPM and the motor sounded horrible and was shaking like mad.

"thanks for the cleaning tip,

"thanks for the cleaning tip, we both will probaly need to do this as i have a '77. he said it turned out to be the plugs, the were fouled and had the wrong ones in. the ones he got are the gapless type, says it runs better in the bucket, i guess well see once it gets in the water.."

Your 135 was originally spec&#

Your 135 was originally spec'd for UL77V's and the latest reference from BRP that I have shows them as still the plug of choice. They are a surface gap plug so there is no electrode poking into the cylinder. I've run them in my Mercury for 40 years. I've always changed them before the start of every season. They require a bit more voltage to get a decent idle and do better with long duration high speed use. So if you have worn out ignition stuff you might have an issue idling.

My evinrude (77 85hp)

My evinrude (77 85hp) runs "normal" plugs and i never had this issue. The engines are basically identical yet mine runs fine. Interesting to say the least. Guess each motor has its own personality..