140 Mercruiser I/O running poorly

goingboeing737 · Mar 13, 2005

I have done a "search" and can not find exactly what I am looking for. 1985 Four Winns 170 Horizon. 140 Mercruiser I/O. I have had the boat in the water about 5 times now. I think she had set for about 6 - 7 months before I bought her. Says she had a tune up and new impeller before I picked her up in Dec. I filled it with new gas and added some Sta-Bil in Dec. Had her in the shop last month to replace the tilt/trim indicator and limit switches and install a depth finder. So, last week I took her out, runs fair, but from idle to WOT, she will sputter and die. If I "baby" or "work" the throttle I can get her to go and get up on plane. (If I were trying to pull a skier, they would drown) Once on plane, she will go great all the way to WOT @ about 37 mph. In neutral, she revs freely and idles good. Took her out yesterday, sputtered, very hard to get up on plane even "babying" the throttle. Died several times while out at low speed. Seems like it is flooding or bogging down is about the only way to describe the feeling... A side note. I left her in the water overnight last month (I have a slip with a lift, but did not use it) The next day, she had taken on quite a bit of water. Enough that the floor ski locker had about 2 inches inside. I had asked the dealer doing the limit switches to check the bellows. I have looked and they "appear" OK. Dealer did not report anything to me about their condition. Any thoughts?? Need more info to diagnois???

trog100 · Mar 13, 2005

Re: 140 Mercruiser I/O running poorly

the fact that it runs okay once u "baby" it up to full speed suggests that the engine is basically sound.. "Says she had a tune up" really mean b-gger all.. so u need to check basic things like plugs.. points.. leads.. cap.. yourself and if none of that produces the goods go for a carb rebuild and fuel-line and filter stuff.. as for drive train stuff and water in your boat well thats whole different ball game.. trog100

Bondo · Mar 13, 2005

Re: 140 Mercruiser I/O running poorly

My 1st Guess is that the Carb needs Rebuilding,... Or Replacement......... You're describing a Fuel Issue.......... On you side note,....... You've got a Leak,....... A Pretty Serious 1 at that......... Definitely Needs More Investigation...........

Don S · Mar 13, 2005

Re: 140 Mercruiser I/O running poorly

The carb could also be flooding at low speed because of a bad fuel pump. Check the clear hose going from the fuel pump to the carb. If there is gas in there, or in the oil, replace the fuel pump.

fireship1 · Mar 13, 2005

Re: 140 Mercruiser I/O running poorly

Hello, If you are getting water in the boat check it out ASAP! Bellows will appear sound until you spread the folds and look in between the pleats. They usually split in between the folds and require some probing to find the tears. You should have had the bellows serviced when the limit and senders were being changed. The housing would have already been apart. Your mechanic should have informed you of this. A torn bellows can sink your boat, rust you u joints and trash your gimbal bearing. Does your engine ever backfire when trying to bring it up to speed? I had the exact same problem with mine and after rebuilding and adjusting the carb with no sucess I found my points had come loose enough to mess up the timing. Someting to look into. Let us know how it goes.

fireship1 · Mar 13, 2005

Re: 140 Mercruiser I/O running poorly

Hello, If you are getting water in the boat check it out ASAP! Bellows will appear sound until you spread the folds and look in between the pleats. They usually split in between the folds and require some probing to find the tears. You should have had the bellows serviced when the limit and senders were being changed. The housing would have already been apart. Your mechanic should have informed you of this. A torn bellows can sink your boat, rust you u joints and trash your gimbal bearing. Does your engine ever backfire when trying to bring it up to speed? I had the exact same problem with mine and after rebuilding and adjusting the carb with no sucess I found my points had come loose enough to mess up the timing. Someting to look into. Let us know how it goes.

goingboeing737 · Apr 2, 2005

Re: 140 Mercruiser I/O running poorly

An Update...... Running Poorly/ hard to get a hole shot>> Still a few issues getting her going while first out on the water, but it's getting better. Only seems to be an issue for about the first 10 - 15 minutes, after that she's fine. The Water Leak > Took it back to the shop that had replaced the T/T limit and indicator switches. When I called to ask them about it, they were very helpful and said they could probably diagnois it on the spot. The thinking was the bellows had "slipped or let go" somewhere. So I rolled in, mechanic came right out, looked it over, and...darn, No Cigar,, the bellows appeared fine. So, I dropped it off. 2 days later the mechanic called to say they had found the culprit. A grommet that goes through the transom for the water inlet had dry rotted and gave up. It took him putting it in the water to finally find it. Probably the other work they had done moved it enough to start leaking. Bottom line. They replaced the grommet got her all sealed up and it cost me a whopping 43.00 Just came back from a short cruise, and all is dry.

trog100 · Apr 3, 2005

Re: 140 Mercruiser I/O running poorly

have u thought about fitting transistorized ignition to the beast.. or at least replace the wires.. cap.. plugs.. points.. give the ignition a general tune up.. trog100

goingboeing737 · Apr 3, 2005

Re: 140 Mercruiser I/O running poorly

I have thought about changing to a "electronic" system. I checked out the plugs, cap etc and they all seem to be in good shape and less than a year old. I don't even own a timing light anymore....

It really "feels" to me that it is a fuel problem. The way it bogs down and dies. I also think it just hasn't been run very much over the last year or 2. I will continue to check it out and let you know what I find. At least she's not sinking

wake5150 · Apr 3, 2005

Re: 140 Mercruiser I/O running poorly

I'd bet dollars to donuts that you need to rebuild your carb. I don't believe it's a fuel pump, it seems to keep up with demand at WOT. If you can Rev it in Neutral but it bogs with load, even when babying it, I'd guess it's a clogged power jet. I'm guessing you have the Rochester 2bbl or the Mercarb 2bbl. Either way you can rebuild it yourself for $50 and a couple hours of your time.

Don S · Apr 3, 2005

Re: 140 Mercruiser I/O running poorly

Still a few issues getting her going while first out on the water, but it's getting better. Only seems to be an issue for about the first 10 - 15 minutes, after that she's fine.

Sounds like your choke is way too tight or not opening properly. When it finally opens all the way all is good. No timing light and probably no dwell meter. No wonder you have a problem, they don't set them selves, and with new points everything is off till it's setup properly. Do you have a manual to know how to set everything?

olbuddyjack · Apr 4, 2005

Re: 140 Mercruiser I/O running poorly

I'm with Bondo and wake. I had a 120 with a rochester 2 jet that did that, replacing the accelerator pump fixed it. It did it 2 times over a period of years and the accelerator pump cured it both times.

140 Mercruiser I/O running poorly

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