Power Loss in Rough Water

[NCSC Matt]

I am having engine problems with my 1988 Sea Ray with a 4.3L 175HP Mercruiser. Engine serial number: B844228, drive serial number OB973836.

Primary Problem: Engine will be running strong, but after hitting some rough water, it will lose power. In some cases it losses power so significantly that I am unable to remain on plane.

While this is happening the engine is running rough and has a ?bogged down? sound to it. If I pump the throttle continually I can bring the RPMs back up to 3000+ RPM range. I can?t replicate this problem every time, but it has been happening more and more. Sometimes I can pump the throttle and it will break through and operate normally. Other times it is so severe the engine stalls.

More Information:

I recently had it in the dealer for rough idle/ staling at idle. They adjusted the idle and replaced the spark plugs. They lake tested it and said it was fine.

I had the ignition coil replaced at the beginning of the season.

The manual says the recommended engine temperature is 143, but last year the dealer said it was running too cool and replaced the thermostat. It now runs around 170 +, hard to tell with my gauge.

Thank you in advance for any help.

 

[Bondo]

Re: Power Loss in Rough Water

Ayuh,....

Change your Fuel Filters.....

 

[arks]

Re: Power Loss in Rough Water

What Bondo said.
Gotta start there and see if it solves the problem. Do you have a fuel/water seperator? If so, then drain it and look for any debris or water.

 

[Haut Medoc]

Re: Power Loss in Rough Water

What Bondo said, & if it persists you will need to look at the fuel pick up screen in the tank & possibly drain the tank itself (debris)......​

 

[chiefalen]

Re: Power Loss in Rough Water

There is a way to get the water and other junk out of the tank without draining it completely. Works best on a trailer.

Crank up the bow of the trailer way up if you have to raise the outdrive so be it.

Remove the anti-siphon valve, and fuel pickup. At this point might as well check them both.

Stick a hose in the tank and the farthest rear corner of the tank lowest point.

And suck out gas into a clear container till you hit clean gas.

Water is heavier than gas and will come out with all the gunk or most of it anyway.

Good luck!

 

[NCSC Matt]

Re: Power Loss in Rough Water

I changed the fuel filter; I only have a paper fuel filter in the fuel pump. It looked very clean, but I changed it anyway. I'm thinking of adding a water seperator, is that hard job?

I also disconnected the fuel line from the carb. There is a small nylon filter in there. It was VERY dirty. Looked like small pieces of rust. I cleaned this filter with carb cleaner and put everything back together. I took it out on the water and the same thing happened (ran great then...first wake I hit it lost power).

I haven't checked the tank yet, but judging by the clean fuel filter and the very dirty nylon filter I'm thinking their is a problem after the fuel filter. The big fitting that is screwed directley into the carb seems a littled rusted. I will buy a replacement for it, but should I get a new metal fuel line as well?

Please let me know what you think. Thanks to all of you for your help. I plan on taking your advice to clean out the tank while it's on the trailer.

 

[JustJason]

Re: Power Loss in Rough Water

if your carb filter was rusty i bet the inside of your carb is gunked up. doesn't take much to clog up carb jets. all those little pieces you saw in the filter, well once they get into the carb 99% of them are to big to get passed by the carb, and remain in the fuel bowl.

 

[NCSC Matt]

Re: Power Loss in Rough Water

Should I replace the fuel lines and rebuild the carb? If so, where is the best place to buy a carb rebuild kit?

 

[NCSC Matt]

Re: Power Loss in Rough Water

Thanks for all of your help. I rebuilt the CARB, and it fixed the first problem, but.... Now it doesn't run well at WOT.

I can only get 3500RPM's out of it. If I push the throttle into or near WOT it slows down a little. It seems to me like it may bet getting too much fuel.

It runs smooth up to 3300RPMs and I hit around 35 knots. I used to be able to do 4000RPMs around 40 knots.

Thanks again for all your help so far, and thanks in advance for any more advice.

Matt

 

[JustJason]

Re: Power Loss in Rough Water

you probably got the float height wrong....
It sounds like your running out of fuel, not that you have to much of it.

 

[sarantis]

Re: Power Loss in Rough Water

my problems started something like that .I hope you aren't experiencing the same problems but take into consideration :
1)when the sea is wavy you need more power to pass the waves
2)temperature problems ? i think a temp sender needs water to send a reliable indication.
in my occasion the result was blown head gasket.
I would suggest a compression test .
And by all means first get a laser gun and get sure about the temperature.

 

[NCSC Matt]

Re: Power Loss in Rough Water

Thanks for the advice:

I changed the thermostat. It lowered my temp, but at low speeds the temp crawls up a little. I?m thinking I will need to change the impeller soon.

I also made an adjustment to the float. It helped a little, but it still doesn?t run strong at WOT. It may be lacking just a little fuel.

My question:

The way I understand it the float has to different adjustments.

1) Bending the piece of metal attached to the plastic ?float?. This affects the angle of the float up or down.
2) Bending the small metal tab that seems to affect the extent of up or down travel.

What should I be adjusting? How much? I already used the little ruler, but it gave me pretty bad results. I?m sure it can be traced back to user error, but I thought I was pretty accurate. What are your suggestions for getting a little more fuel in the engine?