Mariner 45hp Carburetor Leaking after Total Rebuild....stumped!

[christopher425]

Hey Everyone!

I'm a first time boat owner and have found tons of awesome information on this site, so thanks so much for the help! I've got a 1987 Mariner 2-stroke 4cyl 45hp that has two Walbro Carbs (WMA 6-1 on top and WMA 6-3 on bottom). I've rebuilt the carbs with new floats, needles, and gaskets. They've been ultrasonic cleaned and sprayed with carb cleaner as well as using compressed air. I've cleaned all the jets and vents thoroughly several times. The problem I'm having is that I get a small leak that APPEARS on the throttle linkage on the backside. I know it's coming from somewhere else, but this is where it appears. It only happens when the motor is off and it is a very slow drip that comes and goes intermittently. I know the float level/height and needle seating properly is the first thing that comes into mind, but I've taken these things apart so much and made absolute sure that they are spotless and I've even tested them many times before re-attaching to the intake to make sure the floats aren't sticking and that the needles are holding a seal by blowing air by mouth into the fuel pick line. All appears good when I check. The carbs are working great otherwise, but I really need yall's help in solving this issue. I've set the float height at 1/4" from the bottom of the float (when carb is upside down) to the flange. This makes the float be almost perfectly parallel to the flange of the carb body. Does anyone else have the specs for the float level for the WMA 6-1 and 6-3 carbs? I'm working on getting a service manual, but for now 1/4" was the best I could find on the internet. I'm very stumped as to why they both have a small tickle/drip after motor shutdown. Could I have possibly overtightened the float bowl and it's not sealing? I've tapped the bowl with a screwdriver in case it was the float sticking, but that didn't seem to have any effect. Please help gents, I'm greatly appreciative of any assistance. Thanks and have a blessed day!

 

[Dave1027]

Are both carbs leaking?

 

[christopher425]

Yes, both are leaking in the same way.

 

[racerone]

If it is leaking from throttle shafts after shut down it is normal.-----

 

[christopher425]

If it is leaking from throttle shafts after shut down it is normal.

Is that because of the carbs heating up and the pressure being higher? I've read that in a couple places while trying to figure this out...

 

[Dave1027]

Maybe it depends how much is leaking? I don't recall any of the carbs on my merc leaking. Maybe a very small amount?

OP, besides the leaking, how is the motor running? How do the spark plugs look? Are they fouled excessively?

 

[christopher425]

Maybe it depends how much is leaking? I don't recall any of the carbs on my merc leaking. Maybe a very small amount?

OP, besides the leaking, how is the motor running? How do the spark plugs look? Are they fouled excessively?

It is a very small amount. And it's sporadic meaning it will take 15 or so minutes to notice it and then it will stop and may not continue for another hour or so. I've been disconnecting the fuel line that runs from the portable tank just to keep it from leaking overnight.

The plugs are another scenario....I pulled the plugs and the top 3 were very fouled and had carbon buildup, so I know it was running really rich. Cleaned them up really good. Bottom plug was perfectly clean. No water or any milky oil, so I don't believe there's any water invading. Bottom cylinder simply isn't firing. Deduced it to the switch board and have one ordered to replace. Plug, wire, and coil all work when tested and the stator is less than a year old. Going to do a compression test either today or tomorrow, also.

 

[christopher425]

Engine has been running fine up until our last outing. It will crank super easily, idles great. Ran great up until about an hour into our trip and it lost power dramatically, started surging, then it would only go slightly above idle until we made it to the landing. I believe I over adjusted the carb floats and had them too low and it was choking the fuel supply. That combined with only running on 3 cylinders probably was why it bogged down so badly. The trip before it ran fantastic. It's like the more I try to repair this small fuel drip, the more I affect the boat's performance

 

[racerone]

Fuel dripping below throttle shafts is normal after motor stops !!!

 

[christopher425]

Hey everyone,

I've got an '87 Mariner 45hp 2-stroke 4cyl (2 carb) that has no power past 1/2 throttle. She'll crank super easy, idles great, runs great from 1/2 throttle and below. When you try to go any faster, she hits a wall and just stays there. If you back off to 1/2 throttle it picks back up and will hold there. I've looked and the timing IS advancing with the carbs. Throttle plates are synced and fully open at WOT. It doesn't sound like its missing any. I pulled all the plugs and they are all the same color, so that tells me they are all firing.
She ran great up until I installed the floats in the carbs too low, so I thought that was starving it for fuel, but I went back and adjusted them to OEM spec (5/16") and took it on the lake again.....same issue, but not quite as bad.
The first time it started surging as soon as I put it in REV coming off the trailer and it ran WOT fine for a couple of minutes, then gradually kept dropping rpm's until we limped back to the ramp via basically idling.
After taking the carbs apart and getting the float heights to spec, we took it out again. She didn't surge at all backing off the trailer, idled great, but had no power or increase in rpm's after 1/2 throttle. It ran somewhat better, but still super slow.
This seems like an easy fix and I know there are tons of reasons why it has no power at WOT (I've scoured the internet looking at other posts, but no one seems to post how their issue was resolved).
It ran great up until I over-adjusted the floats, so I'm thinking I did something inadvertently and just can't seem to discover that that is. I haven't messed with the flywheel or timing, so I don't think that's in consideration.

Here's what I have done so far:

1) Rebuilt both carbs and thoroughly cleaned (several times)
2) Replaced ALL fuel lines from the tank to the motor
3) New fuel filter
4) Cleaned spark plugs
5) New high-end stator and trigger installed
6) Cleaned fuel tank
7) New primer bulb from Wal-Mart
8) Rebuilt fuel pump
9) Only using non-ethanol gas
10) New switchbox

Things I'm thinking it could be:

1) Water in gas tank from rain (leave the tank vent screw open at all times to keep it from swelling due to heat/sun)
2) Carbs need cleaning AGAIN?
3) Fuel filter caught some debris and is clogged
4) Spark plugs need replacing
5) Linkage between carbs/timing arm are slightly off?

Any help is greatly appreciated fellas. Thanks so much!

 

[Dave1027]

What do you mean "over-adjusted the floats"?

After half throttle or so, it's all on the carbs as the motor is already at max timing. My guess is you still got something wrong with the carbs.

 

[christopher425]

I was having a problem with the needle not seating all the way and I was getting a tiny bit of fuel leaking from the carb after shut down. I overcompensated and set the float height too low. When I found the specs that the float should be at, I realized that and assumed that it was making it seat the inlet to early cutting off the fuel prematurely to the carb bowl.

 

[Dave1027]

Do you have new floats and needle valves?

 

[christopher425]

Yes, I've put in new floats and needle valves. Cleaned them like crazy several times.

 

[christopher425]

I bought some new plugs today and will put them in when I get home.

 

[christopher425]

Installed brand new plugs AND used another tank with fresh gas, but it ran even worse today. The throttle was even less than when we took it out last weekend. When I disconnected my fuel hose, I did notice gas dripping from my quick connect at the end of the fuel line that attaches to my fuel tanks. You think I could be sucking air from that connector end? I'm going to take the carbs back off tomorrow and clean the mess out of them, too.

 

[christopher425]

Hey All! I've got and '87 Mariner 2-stroke 4cyl (model# OB113850). At WOT she's only hitting 4000rpm and I know it should be closer to 5500rpm per the manual. I've done much work on her since I bought her used last summer. She cranks fine, idles fine, runs smooth. It just pegs out at 4000rpm and I can tell there is more power remaining, but it's just not reaching it.
I hooked a timing light up and did notice that at WOT the #2 cylinder is not like the other three. It noticeably has some intermittent spark loss. The other three didn't miss a beat. Yes, my carb throats are all the way open at WOT. I personally don't think it's a fuel issue. Spark is good and jumps a 7/16" gap easily on all cylinders. When I pull each plug wire you can hear the difference when one is dropped off. The acceleration is great and you can feel it get on plane. Compression is good on all cylinders.

Here's what I have done so far:

1) Rebuilt both carbs and thoroughly cleaned (several times)
2) Replaced ALL fuel lines from the tank to the motor
3) New fuel filter
4) New spark plugs
5) New CDI stator and trigger installed
6) Cleaned fuel tank
7) New primer bulb from
8) Rebuilt fuel pump
9) Only using non-ethanol gas
10) New Chinese switchbox from eBay
11) Link & Sync per manual
12) Timing adjusted to spec
13) Faria tachometer installed
14) New rectifier
15) Seafoam to clean carbon deposits
16) New Solas prop per their specs (11.1x13)
17) Cleaned all contacts and leads from trigger, stator, coil, and ground wires

Things I'm thinking it could be:

1) The #2 cylinder ignition coil
2) The Chinese switchbox from eBay has pooped out (I know I should have spent more for a better product)
3) Spark plug wire
4) Manual tilt could have some effect if I try different settings

Since, I've done the above mentioned repairs, its performance has increased dramatically. I really feel that I'm so close to having this issue resolved and reaching full power at WOT. I just need to solve this last riddle.

Any and all help is appreciated. I know you guys are the experts, so let me know what you fellas can come up with. Thanks so much!

 

[racerone]

Post compression test actual values here.-----Water pump impeller replaced ?----Checked exhaust tuner for blockage.----Reed valves checked ?

 

[jimmbo]

Try swapping Plug wire, if the Intermittent spark follows the Wire then that tells you something. If it remains, try swapping a Coil... Check the Plug for any sign of Cracks in the Insulator, or Carbon Tracks on it.

 

[christopher425]

Post compression test actual values here.-----Water pump impeller replaced ?----Checked exhaust tuner for blockage.----Reed valves checked ?

Compression Values are

Cylinder #1 - 120
Cylinder #2 - 125 (This is the one I'm seeing the loss of spark at WOT)
Cylinder #3 - 120
Cylinder #4 - 105

Yes, replaced impeller last summer. Telltale has a good strong stream coming out. Also, checked the exhaust for blockage and couldn't find any. I haven't visually inspected the reeds, but I've used an index card to see if the carbs have any blowback and they don't.