hot weather effects on a Mercury 4 stroke

[happykamper]

I would ask this on the Mercury forum but I do not have my serial number handy Was fishing Friday and my Caymas was performing awesome early on, it done went and got hot that afternoon, 95 degrees, I noticed my 300 R was struggling to get out of the hole, I even checked to make sure my livewells were empty. Saturday morning was just the opposite, a cool front had blown in, the boat jumped out of the hole like a bottle rocket, so my long winded question, does the heat and humidity make a big difference on these 4 strokes ?

[1Holeshot]

The heat and humidity do make a difference but I cannot imagine the 300R being a dog out of the hole. What prop are you running?
If it is a vented prop you could start removing plugs and see if it improves.

[CaymasRodney]

The heat and humidity do make a difference but I cannot imagine the 300R being a dog out of the hole. What prop are you running?
If it is a vented prop you could start removing plugs and see if it improves.

I agree with this, i can't imagine heat killing a four stroke like that, i never experienced that before on my rig, you do have the big gear case right?

[happykamper]

25 Fury 3 blade, all plugs removed. 1.75 torque master. Maybe I need more venting.

[CaymasRodney]

25 Fury 3 blade, all plugs removed. 1.75 torque master. Maybe I need more venting.

If it does it again raise your jack plate some and see if that helps. If it doesn't help you may want to call Mark and see what his thoughts are about adding extra vents, you can always plug them up some

[JSataon]

Same here. I have a new CX 20 Pro (9.3hours) Mercury 250 FS, 24 Fury 3 blade vents unplugged, 8ft Poles, 4 batteries non lithium, 360 mega and Live scope w/ turret. Yesterday morning 61 degrees full tank, wells empty, 500lbs of fishermen and 20 rods and tackle. Jumped out of the hole and ran great. i ran 62-65 mph never pushed it hard with less than 10 hours on it. At 2:30 90 degrees, both wells full, 68 percent fuel it was super slow/sluggish out of the hole. Generally i come out of the hole with the jack plate on 5 or 6. I even ran the plate down to 2 and it didn't help much at all. Do you think i need to try a 23 Fury 3 blade for the heat in NC? Love the boat, any suggestions would be greatly appreciated

[happykamper]

Same here. I have a new CX 20 Pro (9.3hours) Mercury 250 FS, 24 Fury 3 blade vents unplugged, 8ft Poles, 4 batteries non lithium, 360 mega and Live scope w/ turret. Yesterday morning 61 degrees full tank, wells empty, 500lbs of fishermen and 20 rods and tackle. Jumped out of the hole and ran great. i ran 62-65 mph never pushed it hard with less than 10 hours on it. At 2:30 90 degrees, both wells full, 68 percent fuel it was super slow/sluggish out of the hole. Generally i come out of the hole with the jack plate on 5 or 6. I even ran the plate down to 2 and it didn't help much at all. Do you think i need to try a 23 Fury 3 blade for the heat in NC? Love the boat, any suggestions would be greatly appreciated

The 23 Fury would probably work great on tourney day in the heat, you can also run that jack plate up to 15 -20, as soon as the boat starts to climb out of the hole start lowering otherwise it will blow out some.

[Trent R]

Your plugs are fouling, Not a mechanic but my 300 did the same thing until it got so bad that I took it to the shop. Plugs where fouled.

[happykamper]

Your plugs are fouling, Not a mechanic but my 300 did the same thing until it got so bad that I took it to the shop. Plugs where fouled.

I only have about 25 hours on the engine, it only is sluggish in the afternoon heat, in the mornings it jumps right out of the hole.

[Trent R]

I had less than 40 hours. It’s a common problem. My did exactly what your describing.

[Bassin Bob71]

Wouldn't it run rough/miss if any of the plugs are fouled?

[happykamper]

I had less than 40 hours. It’s a common problem. My did exactly what your describing.

Well something is definitely wrong, I aired it out Friday morning, the air temp was around 70, only hit 72, was going into a good wind and had a full tank but that is around 7 mph off, guess i will have the plugs checked and also make sure I am getting wide open throttle.

[CaymasRodney]

Well something is definitely wrong, I aired it out Friday morning, the air temp was around 70, only hit 72, was going into a good wind and had a full tank but that is around 7 mph off, guess i will have the plugs checked and also make sure I am getting wide open throttle.

Might suggest they get a sample of your fuel also, could be water.

[happykamper]

Might suggest they get a sample of your fuel also, could be water.

Funny you should say that, I had forgotten to fill the boat up and had to get 20 gallons ( 150.00 ) from a marina on the water, will have that checked as well, thanks.

[bkwillis1]

One thing I have noticed if you have livewells full really bogs you down. They are HUGE livewells and thats a ton of extra weight. I especially noticed at higher elevations.