Vented cap or not?

On a 95 Johnson 50hp should the fuel cap have a vent or no? Picked up a little rig 3-4 weeks ago and trying to sort out some issues with it. To start with it had sat too long and carbs had to be rebuilt. (The plugs are now wet after fishing trips and get home and check them.) Today I went out for awhile and after warming it up and going full throttle to plane out I noticed it was sluggish getting on plane. Stopped and fished about 2 hours and when cranking to move to another spot it didn't want to crank...even with using the auto primer. I checked the bulb and it was not primed. I pumped it up and noticed it would get about hard and then the next squeeze would go soft again. Got it primed and cranked and it wouldn't plane at all so I squeezed the bulb under full throttle and finally got it planed and sort of limped/hand pumped back to landing. I noticed the tank isn't vented and need to know if it should be. I realize I need a new primer bulb. Any suggestion on the wet plugs welcomed. I've tried adjusting the idle screws going by the sticky in the carb section of the forum. Thanks in advance guy's.

Re: Vented cap or not?

the fuel tank has to be vented, that sticky is for the old motors, not the new ones. on your motor that needle needs to be 4 1/2 turns out from soft seated.

Re: Vented cap or not?

I'll get a vented cap, then soft seat and pull the idle screws out four and a half and fine tune from there. If the plugs are wet I'm thinking the farther out the more richer hence more wetter? Regardless I'll do it. Thanks again.

Re: Vented cap or not?

According to my manual the initial settings for the 1995 50HP carburetors are: 3-1/2 turns for the 2 cylinder 737 cc engine, and 1-3/4 or 2-3/4 turns for the 3 cylinder 913 cc engine depending on the model/carburetor. You may want to check with your factory manual or your service department.

Re: Vented cap or not?

Update here guy's. Installed new OMC primer bulb, adjusted carbs again. She ran well ( except for only going up to 3500 rpms according to tach, it's done this since I got the boat 2-3 weeks ago) for about a mile or so. Then even with WOT it began slowing down gradually untill it was only turning 1800 rpm's. I shut it down and checked the bulb which was okay. Restarted fine but under throttle the same thing...it wouldn't plane and would go to only 1800 rpm's. I shut it down again and after removing the cowl noticed a small linkage arm dangling under the flywheel. The linkage that connects the throttle arm to the timing advance thing under the flywheel had apparently lost the retaining nut and dropped down. After re-connecting the boat ran great....even caught 4 nice fish! Now if I can get the rpm thing covered I'm good to go. Maybe the tach is off. Thanks guy's!

Re: Vented cap or not?

what RPMs are you turning and what size boat do you have and what prop?? also does it do any better if you squeeze your bulb while at WOT?? (this would indicate a weak fuel pump or an cracked fuel line.)

Re: Vented cap or not?

SparkieBoat said:

what RPMs are you turning and what size boat do you have and what prop?? also does it do any better if you squeeze your bulb while at WOT?? (this would indicate a weak fuel pump or an cracked fuel line.)

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It's turning 3500 rpm's and doesn't help to sqeeze bulb while WOT. 15'3" Hydra Sports Z255 with a ss prop. Prop has no markings and I don't know the size or pitch.

Re: Vented cap or not?

boomer2 said:

It's turning 3500 rpm's and doesn't help to sqeeze bulb while WOT. 15'3" Hydra Sports Z255 with a ss prop. Prop has no markings and I don't know the size or pitch.

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It does plane quickly so I'm thinking it shouldn't be over-propped or it *may* be over-propped and the hydra foil is hiding it and killing top end...... ( quoted to me ha ha..long day)

Re: Vented cap or not?

so to your knowledge the boat has never ran over 3500 RPMs?? Also have you checked to be sure the RPM gauge to make sure it is set for a 3 cyl and not a 4 or 6...a little selector on the back of the gauge..what MPH are you running?? I would think you should be doing around 30 MPH in that boat at about 5K RPM.with the right prop..just a guess though

Re: Vented cap or not?

SparkieBoat said:

so to your knowledge the boat has never ran over 3500 RPMs?? Also have you checked to be sure the RPM gauge to make sure it is set for a 3 cyl and not a 4 or 6...a little selector on the back of the gauge..what MPH are you running?? I would think you should be doing around 30 MPH in that boat at about 5K RPM.with the right prop..just a guess though

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Not to my knowledge. Have not checked rpm gauge. This is a two cylinder. Don't have speedometer. Only tach, trim gauge and engine systems check gauge. Seat of the pants feeling on speed is 35-40.

Re: Vented cap or not?

Got to go away for a few days. When I get back and look into the problem will update what I find if anything.

Re: Vented cap or not?

check your MPH with a portable GPS...if your getting 35-40 you dont have a problem..just a gauge issue