Johnson V-4 85hp Hard starting and Won't Idle

[TheOutboardKid]

1976 Johnson-Javelin 85hp Model: 85ETLR76G

I was out on the lake last weekend and I had a hard time starting the motor. I tried everything, choke, no choke, more throttle, less throttle, pump the primer bulb, etc. It would sputter for a split second and then die. I finally got it to run after causing a traffic buildup at the boat ramp, but it wouldn't run if I lowered the warmup lever. Once I got out and gave it some throttle, it ran great from 2000 RPM all the way to 5500. It is the second time I've had it in the water, and it idled fine the first time I took it out. It also ran fine on muffs. Gas was brand new, carbs rebuilt in 2017 by the previous owner, along with the power pack and coils replaced in 2016. Compression is 110-115 on all 4 in 2017. (according to the previous owner) I haven't done anything to this motor besides lower unit oil.

I'm thinking it's a fuel issue... but I'm not a pro. Any advice would be appreciated. Thanks!

 

[Tassie 1]

Does sound like a " fuel system "
" 2nd time you've used it "
how long ago was the first use?

I'm thinking the carb needs another pull down and proper cleaning due to " varnish buildup "

 

[TheOutboardKid]

The first use was in last November. I've spent the winter working on the actual boat.

I briefly considered varnish buildup as a cause, but the V4's drain the gas in the carbs into the airbox when you tilt them upwards, and mine had been tilted up all winter, and there was stabilizer in the gas.

It just occurred to be that the fuel filter could be partly clogged and the fuel pump is unable to suck through the filter at low RPM. I'll check it tomorrow.

 

[racerone]

I would do a compression test ----TODAY----On this motor.----It is the first step in proper trouble shooting.

 

[TheOutboardKid]

I did a compression test earlier today. All four cylinders were between 106-110 psi. I got it to start up and run, but it was running rough and idling at about 900 RPM on earmuffs. I don't think this is caused by a lack of fuel, it seemed like there was plenty of gas getting to the carbs. Maybe the idle is too low? Or the mixture is off? Is there a good way to tell if the mixture isn't correct?

 

[racerone]

Remove bypass cover on the cylinder with 106 PSI reading.----Allows you to look at piston & rings.----Might cost you a $2.00 gasket to learn something.

 

[TheOutboardKid]

I've actually had it off before, the gasket was leaking so I installed a new one and checked out the piston at the same time. It did have some wear, but not big scratches or scraping. It's a bit on the low side, but I'm ok with 106 psi for now.

Edit: I forgot to add that I replaced the gasket on the first post, sorry about that!