1987 35 horse carb replacement

[Babernathy1]

Bought a new to me boat last winter with a 1987 35 horse mercury on it. Had 0 problems with it the first few outings then it broke down on me and hasn't ran since January. Everything on it seems fine and I'm almost 100% certain it is a carburetor problem. This model has the side bowl carburetor (whose idle mixture screw and other nuts are always backing out) and I have rebuilt and cleaned it as well as had a "professional" do the same and the thing still will not run worth a crap. From what I've read this is just a terrible carburetor and I want to switch from it. Has anyone ever had any luck using a carburetor that was designed for a different motor. And if so will it work? Any suggestions as to where to buy and what carburetor will work? Any help is greatly appreciated.

 

[racerone]

Mercury has made a lot of motors !------They do not have inherent problems with idle mixture screws / nuts backing out.-----Serial # of your motor ?-----Pictures of the parts that go loose ?---They used that style carburetor for more than 30 years with few issues like yours appears to have ??------Something seems wrong here.

 

[jimmbo]

Until you explain what the motor is doing, you aren't going to get much troubleshooting advice. Parts loosen from vibration. What is the condition of the prop and prop shaft?

 

[racerone]

There may be something wrong with your motor !-----And it is not the style of carburetor on it at this time.----Where did you read that this is a " terrible carburetor " as I am curious ?

 

[Babernathy1]

Let me start from the beginning.. my 3rd or 4th outing the boat had a breakdown and I had to drag It back to the ramp. I am a new boat owner but have been working on small engines as a hobby for a few years but I claim to be NO professional so bear with me. I initially diagnosed the breakdown to bad gas, since I had filled the boat up at the only available non-ethanol gas station in my area (and it was a shady gas station). So I figured there was probably water in my gas can and It just needed a carb cleaning and I'd be good to go. Upon further inspection I realized the nut above the idle mixture screw was missing and I later found it in the bottom of the engine cowl. You can see from the picture that the nut is not in the hole where it is supposed to be and you can also see that the idle mixture screw is backed out quite a bit from the rattling of the motor. I gave the carb a quick cleaning and put it back together the way it is supposed to be and the motor would only crank if I sprayed starting fluid in the motor while cranking at the same time. Sometimes it will stay running if I hold the gas wide-open but most of the time it dies when the starting fluid runs out. If it does stay running (only at wide open) I can sit there and watch the idle mixture screw back out. Needless to say, I can not properly adjust the carb if the idle-mixture screw is constantly spinning. The motor has not cranked without starting fluid since the breakdown so I know it has to be something to do with the fuel consumption. I have re-built the carburetor and have had no change in results as well as have consulted my owners manual. I even tried to take it to my local mercury dealer but because that carburetor is so difficult to find parts for the mercury dealer passed and recommended me to a shade tree mechanic who was un-able to fix it. However we both agreed it was a carburetor problem. Compression is 135-140 for both cylinders and the spark plugs have been replaced and are sparking like crazy. I've put new high octane non-ethanol gas in the gas can and changed all filters. Im only 20 and am in school so getting a new motor is going to have to wait a few years, so I figure I might as well learn how to work on the one I've got. At this point the only solution I have is to find another carburetor that will fit and has more parts available. The serial number for the motor is OMCL0823K001.

 

[jimmbo]

Starting Fluid is a great way to Execute a 2 Stroke. Did you try spraying some mixed fuel into the carb? Do you have a spark that can jump a 7/16" gap? If fuel getting to the carb? Fuel filters clean? Is the float set correctly? Does that engine have a Choke or does it used the Enrichment System to aid Cold Starting?
That design of carb was used for many years, and is usually very reliable.
BTW, you need to post one or two more times before you can upload photos.

 

[Babernathy1]

Starting Fluid is a great way to Execute a 2 Stroke. Did you try spraying some mixed fuel into the carb? Do you have a spark that can jump a 7/16" gap? If fuel getting to the carb? Fuel filters clean? Is the float set correctly? Does that engine have a Choke or does it used the Enrichment System to aid Cold Starting?
That design of carb was used for many years, and is usually very reliable.
BTW, you need to post one or two more times before you can upload photos.

Fuel is getting to the carb, if I squeeze the bulb real hard I can see it trickle out of the jet. I have tried using mixed fuel and I get the same result as when I used the starting fluid. Fuel filters are brand new. Float seemed to be set correctly going off of the owners manual that had a very similar carb. I can't seem to find an exact replica of this carb in any manual anywhere even though I've got the manual for this motor from the correct time period. (which is another big reason I want a different carb). It is possible that the spark plugs can't jump a 7/16 gap, how would I tell? I took the old spark plugs to Napa and they gave me what they said was the same plugs but it is possible they aren't. The motor has a choke but I never had to use it when cold starting and when I use it now I get no results.

 

[jimmbo]

Fuel is getting to the carb, if I squeeze the bulb real hard I can see it trickle out of the jet. I have tried using mixed fuel and I get the same result as when I used the starting fluid. Fuel filters are brand new. Float seemed to be set correctly going off of the owners manual that had a very similar carb. I can't seem to find an exact replica of this carb in any manual anywhere even though I've got the manual for this motor from the correct time period. (which is another big reason I want a different carb). It is possible that the spark plugs can't jump a 7/16 gap, how would I tell? I took the old spark plugs to Napa and they gave me what they said was the same plugs but it is possible they aren't. The motor has a choke but I never had to use it when cold starting and when I use it now I get no results.

Trickle out of what jet? Do you mean the Air Bleed/Bowl Vent? How hard are you squeezing the Primer Bulb?

Well, the mixed fuel will at least provide some Lubrication, while the Ether(Starting Fluid) will wash any off.

'Very Similar' to you, might be a get deal different to others.

You can make a Spark Tester. with a board, a couple of Nails 7/16" apart and bit of ingenuity to connect the plug to one side and the other to ground.(just don't puncture the High Tension Lead)

What plugs did they give you?

 

[hardwater fisherman]

I do not think the serial number you gave is correct.. Any ones I have seen are either 7 numbers or 1 letter followed by 6 numbers...