Cant Take off!

[Eclipse223]

well i have a 1987 Stratos 179V with a 1988 Merc 1150/115hp and it will bog down when i try to take off! i have to raise the eng. way up just to get it to give rpm then trim it back down to plane out! If i dont do this then it will just sputter and act like its cutting out! Now after i have ran it some time and when i come to a stop if i dont let the water run up very far on the outboard then it will not do it. i am up for ideas on what to do. If you need more info just let me know.

Thanks

Brien

 

[sschefer]

Re: Cant Take off!

I'm not familiar with that engine but I am with the symptom. Do a compression test and post the results. We can tell you more then.

 

[Eclipse223]

Re: Cant Take off!

That should have nothing to do with it. the eng runs great once it ets going almost like its getting fludded out by water. or something.

 

[achris]

Re: Cant Take off!

Common problem... Sounds very much like the idle mixtures are a little too weak. To verify that, just as the engine starts to quit, push the the choke button for a second. If it takes off like a race horse, then take the covers off the engine and open (anti-clockwise) the idle mixture screws (all 3 of them) 1/8 to 1/4 turn....

Chris......

 

[Eclipse223]

Re: Cant Take off!

So i tryed doing the choke on it and it killed it instead... So. Once again it wont take off out of the hole it wil just like half way rev and will stay that way just make a big wake ugh. But if i rase the outboard half wayout of the water it just takes off! so then i have the nose of the boat all the wya up in the air till i get the eng. lowered back down and it just keeps running great. So it just when i try to take off. Any ideas Thanks


Brien

 

[ENSIGN]

Re: Cant Take off!

You may just have a mounting issue,when the motor is trimed down is the cavitation plate even with the bottom of the boat?

 

[sschefer]

Re: Cant Take off!

Low compression and backpressure from the engines exhaust being buried in the water leads to excessive fuel retention in the cylinders creating a flooded condition. Once the engine is allowed to clear the excess fuel (raised to relieve back pressure) it will run.

 

[Eclipse223]

Re: Cant Take off!

sschefer


So what do i do about that?

 

[achris]

Re: Cant Take off!

How low does the boat sit in the water? If it's sitting too low, then that will cause the engine exhaust backpressure.

Chris.......

 

[sschefer]

Re: Cant Take off!

sschefer


So what do i do about that?

The first thing to do would be a compression check to see if it is low or not. If it's not then you want to direct your attention to what aChris is asking about.

 

[Eclipse223]

Re: Cant Take off!

I dont think it is to low i have had 2 other bass boats and sets about the same i would say. but once it gets going it runs great boat will run upper 50's and even if i am am just crusing along at 20 or 30 it runs great then also. i am so lost on what it could be.

Thanks for the help everyone.

 

[achris]

Re: Cant Take off!

Try dropping one prop size (2" less pitch)....

 

[CharlieB]

Re: Cant Take off!

Has it ALWAYS ran like this or is this a new problem?

Idle mixture is critical to acceleration.

Once the carbs are CLEANED, float levels adjusted CORRECTLY, idle mixture is adjusted while on-the-water in Forward gear, adjust each carb to achieve the BEST idle speed possible, then back each mixture screw out an additional 1/8 turn to allow additional fuel for acceleration.

To little idle fuel and the motor will bog, hesitate, and/or backfire when attempting to throttle because the water pressure (backpressure) of the water in the lower unit and mid section.

This sounds exactly why your motor will accelerate only when tilted up, once you get it up and off the idle circuit the main circuit fuels the motor correctly and top end runs just fine.

Achris, sshaffer and I have been doing this for quite a while, if they advise you to check something you can bet there is sound reasoning for it, most of the time we are just to busy to take the time to explain it.