91 dt 150 bogging

[lifetime62]

good morning to all
my super six dt150 when I am running it won't plane up , and once it does it only goes approx. 4500 rpm , which it was doing around 5500 rpm's , I am low on fuel ,and I am running the cheap gas , I had the carbs all cleaned and the fuel lines replaced , the fuel pumps cleaned and replaced all the check valves, I am going to put the 100 % gas in today , I turned the mixtures up a 1/2 turn last night ( but haven't tried it yet , I had sea foam in the tank but I have added gas to since then , ????

second problem , when I am trailering if I jump on the motor and tilt the motor up and give it the gas the tilt comes back down , like it isn't holding the pressure, going down the lake it does great , but I know the motor force helps that way . any ideas ????

[Solarman]

dt150, running issues

Turned the mixture up? What do you mean? If you mean the mixture screws on carbs, those screws work for idle settings. Turning those screws inward makes motor run richer from idle to about 2500. Turning them out more makes motor run leaner. If motor ran great before, turn them back. Try pumping bulb if bogging down.

Your tilt cylinder, has it been giving problems?, did you check fluid by the manual?

Check plugs for color, too black- idle mixture too rich. Too light- idle mixture may be too lean.

Post back when able.

[lifetime62]

The plugs are black .look at pic and if hoses are right and left me know .I think the hoses are backwards the bottom pump hose is going to the top carbe and the top hose are going to the CARB's the top hoses

[lifetime62]

How do you check the trim fluid and what do you put in

[Solarman]

The hoses look to be in right places. The top fuel pump feeds between the bottom and middle carbs, and the starter valve. Then the lower fuel pump feeds between the middle and top carbs.
Are all the plugs black, or just certain cylinders? If all plugs are black, then all mixture screws should be opened up 1/8th of a turn to allow more air to mix with fuel at idle.
A pic of the plugs in their respective cylinder order can tell a story. Especially on your motor because each of your two barrel carbs supply fuel and air to one cylinder on each bank (one cylinder on port bank, and one cylinder on starboard bank).

The reason I said check your trim cylinder fluid by the book, is all trims are not identical. If you check by your manual, it will tell you how full it should be, and the fluid to add if needed.

Good luck, post what you find.

[lifetime62]

Oh they were black bad changed them and runs good

[lifetime62]

bogs

I checked all the things and I changed the plugs , run it yesterday 2 ppl and full tank of gas was running 61 at 5800 rpm's
I did do a compression test tonight and I am running 108 to 110 on all cylinders
I did lean it out just alittle more , the plugs were black but not as bad

[Solarman]

Sounds good, thnx for letting us know. Remember black plugs are not good. You should have brown plugs. Not light brown, but enough brown to say it it's getting oil, but the oil is burning like it should.
Also, 5800 is a little high, especially with 2 in the boat, you should be running right at 5600 tops. Running at 5800 is a little to hard on such an old motor, you should consider changing props to next pitch up, if you want it to last, plus you might get an extra few mph's out of it. Safe rpm's for your motor are 5500 to 5600 max.

Good luck, keep it safe. Happy boating.