Merc 35 carb missing a piece?

[Pslater]

Hello and thanks for the wealth of info. Can anyone tell me what #19 is in this diagram? When I disassembled my carb I do not see anything like it.

https://www.marineengine.com/parts/...5-2-cyl/209608-and-up-can/carburetor-assembly

I have been trying to get my fresh rebuilt 35hp sorted out. Cannot get this thing to idle at all. I have timed the engine, set max advance. I checked that the base timing while cranking was about 3*BTDC. I have also cleaned the carb and replaced the plugs. At this point, on the hose, throttle linkage disconnected, I have to be at least 1/2 throttle for it to start. It revs ok but if I close the throttle it just dies quickly. Hitting it with a little carb cleaner does not make it run any longer/dies just as quick.

I decided to try cleaning the carb a second time after going through the ignition timing procedure. Looking through the manual it references removing the “idle tube” from the top of the carb. I do not see a tube or anything like #19 in the diagram I linked. Am I missing a piece? Any guidance greatly appreciated.

 

[Pslater]

The link to the diagram didn’t work. #19 this diagram.

 

[Mark ofs]

I have Mercury 35hp (2 cyl). On the parts list I have for this it states "#19 - NSS - Not Sold Seperate Idle Tube"

 

[Pslater]

Thank you. Here is another thread that shows pics of a very similar carb. It has detailed pics of the idle tube that has threads on top. The thread is referencing a larger engine. Does anyone know if my 35 is supposed to have this?

 

[Chris1956]

Take a look on the crowleymarine web site. You can look your motor up by serial or year and HP.

That piece is an idle restrictor, however, it is Mercury's term for an idle jet.

 

[Pslater]

Here is a pic of my carb after removing the plug and the adjustment needle.

 

[Pslater]

“Idle restrictor” “idle jet” “ idle tube”......what I need to determine is if I am missing #19 or if my carb is a little different and the brass piece in my picture is it?

 

[Chris1956]

There is clearly a brass tube in the carb. Most of those sidebowl carbs had a screw in idle restrictor tube. Looks like a standard jet, but with a tube attached.

Do you see threads above that brass tube? If so, the top of the jet may have been broken off.

 

[Faztbullet]

That the later model WMK series an that tube is pressed in where the older one screwed in...

 

[Pslater]

Yeah, your right. Thank you for the responses. There are no threads immediately above the pressed in tube. My float setting was a little off and I thoroughly cleaned the carb again. I’ll try it again this evening.

 

[Mark ofs]

I am not an expert on this, however have the same carb...and cleaned it this spring, outboard started right up after cleaning then wouldn't start again. Needed to rebuild the fuel pump, which was disintegrating. After that needed to reclean the carb again. if you don't have a manual, make sure that the spring on the float measures 3/32" from top of float to top of spring, when holding the float cover upright, from the tip of the secondary closing lever to the primary closing lever should be 1/4" distance, then holding the cover upside down, so the levers close the needle, measuring from the top of the secondary lever to the shoulder on the float cover should be 13/32", otherwise carb will flood, found this the hard way (originally didn't checked the 13/32", needed to take off again and fix)
Starting at the recommended 1-1/2 to 2 turns out on the idle adjustment screw, the outboard would not run. We have wound up being out more like 4-turns, don't remember the count right now...

 

[Pslater]

Thanks again for the responses. My carb is definitely clean, clean clean. I do have a manual. Made a minor adjustment to the float and that is all. Put the carb back on this evening and have the exact same symptoms.

I feel like I must be missing something silly here. Is cylinder number 1 the top or bottom cylinder? My manual is on my work computer.....I have checked the TDC mark on the flywheel and the top cylinder is at TDC. I’m assuming that the top is #1. Timed it based on that.

 

[Chris1956]

Top cylinder is indeed #1.

A lot of Mercs have a low speed winding and a high speed winding on their stators. You might see if your low speed winding is bad.

 

[Baitcooler]

I just cleaned mine and it did not have that #19 piece.

 

[Pslater]

Baitcooler- thanks , thats good to know.

Chris 1956-

Thanks for the idea. My timing light continues to flash until it dies and I have spark that jumps 1/2" with the throttle in the closed position. Is that enough of a test for a low speed stator issue?

 

[Pslater]

I'm not sure if I should start a new thread since I have established that my carb is not missing a piece and still have issues but I decided to do a recap here, to put all info in one post.

I obtained this 35hp merc with an idling issue, it won't idle at all. At the time I suspected a dirty carb. I did a compression test at the time and it was 140psi on both cylinders. I pulled and cleaned the carb with no change. At that time I discovered that I was getting water in the bottom cylinder. I pulled the power head to do a lower crank seal and discovered that the lower crank bearing was totally shot and probably was the reason for the seal failure. At that point, I rebuilt the power head entirely, replaced all needle bearings, upper and lower crank bearings, and rings. Replaced all seals and o rings etc.

After re-installing the power head, I briefly fired up the motor in the driveway. My plan was to take it to the water, set the timing, and then go break in my new rings. So...took it to the water and never could get it to run well enough to plane out or idle. Been messing with it on a hose ever since and here is what I have checked thus far....

1-TIMING:

I did not have a thorough enough understanding of the timing procedure when I first took to water but now I at least feel like I do. I have the timing set to about 3BTDC when the throttle arm just makes contact and passes the 3btdc as the throttle plate begins to open. The throttle plate fully opens. With the cable unhooked I set the max advance at about 24 while cranking. I am planning to recheck the max advance on the water if it ever runs well enough to put on the water.

2: CARB

- I started this post thinking maybe I was missing the idle tube/jet. I am now confident its there. I verified and adjusted the float level per the manual. I have cleaned the carb thoroughly. Removed the welch plug to clean the idle holes in the carb throat. The fuel tank primer bulb pumps up and gets firm, the carb does not over-flow.

3- Ignition

-Its got new plugs, and the spark jumps 1/2 inch, thats all I know about this ignition system other than the timing procedure was created by some engineer from the future that's way smarter than me.

4-Compression

Just rechecked it. Still 140 on both


As of now, with the throttle closed, the engine cranks over and does not hit a lick, choked or not. I have the throttle cable unhooked. If I move the throttle to about 3/4, it fires right up and will run as long as you want. I can reduce the rpm to a point. I don't have a tach hooked up but I'm guessing if you get below 2k rpm is when it has issues. Once I find as low as I can get it to run, it will continue to run in that position for a bit and then seems like it loads up the plugs a little. You can rev it and it clears up again. The ignition timing is somewhere around 15btdc at the spot where it will stay running at the lower rpm. If I have it running smoothly at higher RPM and abruptly close the throttle it acts the same as if you turned off the key. Just dies quickly and never hits a lick on the way down. If I get the rpm as low as possible and squeeze the primer bulb it dies. If i have the rpm somewhat higher and squeeze the bulb it reduces the RPM and then speeds back up once it recovers. If I close the throttle and try to keep it running on carb cleaner(I know bad idea) it still doesn't hit a lick. This makes me think it is just too rich for some reason. I looked up the main jet # and it matches the parts catalog. As far as I can tell, the idle tube is it's own metering device...? I don't see a separate idle jet that is, other than the needle adjustment and the tube I thought I was missing.

At this point I'm open and appreciative of any ideas. I've got to be missing something simple.

 

[Chris1956]

Sounds like your low speed windings on your stator are bad, that is, if you have them. You might grab a wiring diagram and see which ones they are.

Larger Mercs have low and high speed stator windings. Not sure what you have.

A service manual for your motor will give the expected ohms of resistance for good stator windings.

 

[Faztbullet]

You missed something on carb/fuel/refresh set up..

 

[Mark ofs]

According to the timing notes in the manual I have...it states "Primary Pickup at Idle is 3*BTDC" as you have, but under general notes you also need "29* BTDC at cranking speed"

 

[Pslater]

The sticker on the front of the engine says something like that. I do not see how that setting could be obtainable. It doesn’t make sense.