Real Carb Trouble

[jeffray72]

Im pulling my hair out with this motor. A mercury 50 hp like a 80 model.
I have cleaned and cleaned the carbs over and over and it still seems like the motor is not getting enough fuel. I have tried adjusting the carbs on the water with no success.
Any idea guys what might be going wrong?
What is the best solution to soak the carbs in?

The motor will not run or peak out at fuel throttle and its bogging the entire time. I have cleaned the carbs probably 6-8 times.
The compression was checked and i was told it was like 120. Is this low compression? The guy at the marina said it was good pressure.....

 

[roscoe]

Have you got a repair manual?
Set carbs to recommended starting set points ?
Did you follow the link n sync directions after installing the carbs ?
Are the carbs fully open when at full throttle?

Compression of 120 is fine.

 

[Chris1956]

Pump your fuel primer bulb and see if that helps. If so, fuel delivery is an issue. Fuel pump, anti-siphon valve or filters are suspects.

 

[racerone]

It sounds to me that it is NOT a carburetor problem if they have been cleaned 8 times !!!-----Do you have spark on all 4 leads ?-----Water pump replaced recently ?-----Looked up into the exhaust tuner for exhaust blockage ?----Lower crankshaft seal could be leaking.-----Reed valve could be broken.-----Did this problem start suddenly ?----How long have you owned this motor ?

 

[jeffray72]

I dont have a repair manual.
I set the air/fuel mixture screw to starting set. It did well on the muffs but completely different or total opposite on the water. I tried to set the mixture while in forward on the water and it did not run well. On the muffs in forward it ran full throttle.
I did not check to see if carbs were fully open.
I replaced the fuel primer bulb with a new one. The fuel pumps have all new components, gaskets, etc... filter screens looked fine. I have tried running it with the gas cap off even, no difference. Carbs have all new gaskets, diaphragms etc...
I have spark on all 4 leads last time i checked.
When you say water pump do you mean impeller? I think it was. I have had the boat for 2 months and i havent had it to run correctly yet. But i did ask the guy if the impeller had been replaced recently and he said he thought so, who knows. It does pee water well.
Where are the reed valves on this motor.? I havent saw any and i have been looking.

racerone you mention the exhaust tuner; when i got back home yesterday from trying to get carbs adjusted i noticed there is a leak of what looks like a lot of carbon buildup and it looks like there is some coming from where the prop attaches because i can see where it has ran down the inside outer edge of the prop and there is more than just a few drips on the ground. I dont know all the boating terminology but i am highly mechanically inclined so i dont know the word to definitely point this in the right direction but anyways as i was trying to adjust the carbs yesterday i saw there was water coming out of where like the motor cover stops and the shaft begins. I was also getting 2 cycle smoke up by the front of the motor in the area where the motor cover stops. When i say front im talking about the part of motor facing the boat. So how do i inspect the exhaust tuner? How do i get to it?
Or have i done blowed the motor up, lol?

 

[racerone]

Reed valves are internal on reed blocks around the crankshaft.-----And winding it up on a hose means nothing.

 

[jeffray72]

Ok, any suggestions?

 

[jimmbo]

Can the Spark jump a 7/16" gap on all cylinders?
To look up the exhaust housing, you either need a camera, or you remove the gearcase then look up the midsection housing.
But the First thing you to do is a Compression Test. Running on a hose means very little, except at least one Cylinder is firing. Revving it on the hose, or in Neutral, is great way to Destroy it

 

[jeffray72]

Ok jimmbo,

Sorry for the delay but i finally got around to checking things out.

The spark will jump 7/16 on all cylinders.
I actually took the foot off the motor today and the exhaust port/tunnel looks fine as far as i can see. I cant see at the very top edges of the tunnel of course and i really dont know what i would be looking for but as far as i can see there are no buildups of carbon or anything.
Im only assuming the compression is good at the moment. The marina tested it probably 6 weeks ago and it was 120.
The motor ran great on the muffs but bogged, no power on the water.
Any idea guys what to check next? I will check the compression just to clear that once i can get the tool to test it with.
Thank you guys for your help.

 

[jeffray72]

When i pulled the foot off this fell out. I cant find where they should go. The rubber washer/seal is torn. Any idea guys?
Working on this boat motor is my first time. I have worked on all sorts of motors/engines with great success so im beginning to learn a little on these.
Thank you for your time guys

 

[jimmbo]

First of all you need a new Water Pump Housing, might as well get the Complete Kit, as it will have the Upper and lower housings, Impeller, gaskets, bottom plate, slinger, Instructions etc, etc.
The Second pic shows the a piece of the Reverse Lock Mechanism. It fits in the midsection and the shift shaft fits through the middle of it, in conjunction with the cam, still on the shift shaft, in the lower unit, it moves up and down, locking and releasing the Reverse Lock, depending on which gear the motor is in
The 'Washer' looks like the Slinger that sits immediately above the Water Pump on the driveshaft.

 

[jeffray72]

jimmbo youre exactly right. I finally figured it out.
I should probably check my compression before i buy a water pump housing/kit right? What do you see wrong with this water pump housing? Would this cause the poor running on the water?
Thank you for your awesome information.

 

[jimmbo]

At a quick glance(on a phone)I thought the pump housing had been busted, that was just a notch to allow wrench clearance. So you can probably reuse the housing.
Yes do the compression test. Before spending any money.

 

[jeffray72]

10-4 good buddy.
I will get back to you on the compression test.
Thank you

 

[jeffray72]

Hi guys,

So here is the story. Im sorry for the delay also.

I went friday and purchased a compression test kit from harbor freight. Even though i had watched a guy on youtube use the same tester and he said it was no good. Im hard headed myself.
Anyways the tester from harbor freight registered 60 lbs on all cylinders same as the one the guy was using in the video. I took it back for a refund. I borrowed one from my uncle the next day and it would not hold pressure.
Today my uncle found another one he had so i borrowed it. All cylinders are 120 lbs, thank god. I was worried.
So where should i go from here?

Thank you in advance for any ideas on this issue.

 

[jeffray72]

**UPDATE** when i said "60 lbs on all cylinders same as the one the guy was using in the video" thats the exact lbs of pressure he got on the same compression tester also... anyways, just thought i would throw that out there. Dont any one seem to have a clue anyway...

 

[Chris1956]

As long as the compression numbers are the same between cylinders, the motor is likely good.

Compression testers can be inaccurate, but they are usually reliable. That is, if they show the same compression on all cylinders, all cylinders will normally have the same compression, although the exact PSI is not accurate. Consistent compression across cylinders is the spec for outboards.

 

[Mercurylips]

Jeefray72- This was like reading a synopsis of my adventures with a Merc 500 (similar vintage). After excess carb cleaning I finally got disgusted and started to look elsewhere for my problems. I was lucky enough to hit on the main cause of my plight by trying out a new stator. (It was going to get replaced anyway due to the wiring losing it's insulation and it's trustworthiness). The motor had enough power then and the rest of the problems cropped up due to the fuel lines degrading and leaving black particles in the main jets. Cost about a buck to replace those. The other wiring harnesses also got replaced. After feeling confident that the worst was behind, I took the boat for a good road trip on a rough road. That caused one of the main jets to loosen and drop into the bowl. The biggest help I got was from the gentlemen on the forums and a decent service manual. If I was proficient with the electronic testers, I wouldn't have wasted an entire fishing season wrestling with the problems.

 

[jeffray72]

Mercurylips, thank you so much and thank you for your well put together post. I have a guy with one of these motors so im going to get it. He quoted me $75. Motor is good but he mentioned something about a exhaust plate or such has holes in it and its not worth repairing but it has all electronics.
Just how does a exhaust plate or whatever get holes in it? Im not even sure it is the exhaust plate but that was my understanding. Im not a boat mechanic, this is my first. Im great with vehicles.
Thank you Mercurylips

 

[Mercurylips]

Mercurylips, thank you so much and thank you for your well put together post. I have a guy with one of these motors so im going to get it. He quoted me $75. Motor is good but he mentioned something about a exhaust plate or such has holes in it and its not worth repairing but it has all electronics.
Just how does a exhaust plate or whatever get holes in it? Im not even sure it is the exhaust plate but that was my understanding. Im not a boat mechanic, this is my first. Im great with vehicles.
Thank you Mercurylips

I am not sure about an exhaust plate causing you (or me or anyone) any grief. Some of the folks on here with more experience in "exhaust plates" will have to help. BTW...I'm not that great with vehicles either. I am just thick headed and stubborn enough to try to fix stuff that I think I can do.