Sneezing through top carb

[Freezebear]

Ok, I'm stumped! My motor was idling poorly a few months ago and fixed it by a sync&link adjustment per the manual. Everything ran great after that. Now motor is sneezing through top carb and won't idle. Checked plugs and changed. Checked coils and tried adjusting fuel mixture, pulled needle on top carb and blew through port and tried again. Once, I get it running at 2000 RPM it's OK, any lower than that and it starts sneezing from top carb. I can see a little mist come out of carb. I can hold a piece of paper in front of all carbs and get a little fuel spray on it. I regularly use Ringfree and maintain my boat very well. What else should I check? I have scanned the posts and have come up with checking check valves, but do not know where they are. Manual doesn't even mention these. Maybe a reed, but it doesn't do it over 2000 rpm's. Also I'm only getting 5900 instead of my ususal 6000at WOT. Please help.

 

[DJ]

Re: Sneezing through top carb

Freeze,<br /><br />Sneezing is an indication of a lean mixture.<br /><br />What kind of engine is this?

 

[Freezebear]

Re: Sneezing through top carb

It's a 3 cyl. 60HP Tracker. I just got back in from looking at it again. I removed the VRO pump and checked the hoses. All OK, but are going to replace all fuel hoses upon reassembly. I found what i believe to be a check valve screwed into the block behind the VRO. Removed and blew air through it both ways and it passes air either way. I am blowing through it with my mouth to test. Do I need more pressure to test it?

 

[OBJ]

Re: Sneezing through top carb

Freeze....what color is the "check valve"? If it's blue and brass colored, it's your pulse limiter for the VRO pump. Takes about a larger than 13/16" socket to get it out.

 

[Freezebear]

Re: Sneezing through top carb

Yes, it's kind of blue color and took a large socket to get out and connects with a hose to the VRO. I took the pulse limiter and blew through it with about 150 psi and then it closes. Is this normal? My VRO has been bypassed, so I guess there is a mechanical fuel pump built into the VRO. I am at a standstill now until I can figure out what to check next. Please keep the thoughts coming.

 

[OBJ]

Re: Sneezing through top carb

That's a lot of air pressure for the limiter. But it works anyhow. It did what it's supposed to do. It protects the VRO pump from large hard pulses from the crank case. There is no mechanical mechanical fuel pump built into the VRO. It works off of cankcase pressure/vac. Put the thing back together making sure all hose connections are tight. Your problem probably is in the top carb. Some junk in there plugging up the jets.<br /><br />If you don't own one, get a manual. It will save you hours of guess work and help you troubleshoot these kind of problems. OEMs are preferred but you can get the generics here at iboats. Check the link below for OEM.<br /><br /> http://www.marineengine.com/manuals/johnson/ <br /><br />or<br /><br /> http://ww3.kencook.com/evinrudejohnsonmanuals/

 

[Freezebear]

Re: Sneezing through top carb

I got 2 manuals for this motor. I have the Clymers and the Seloc ones. They helped some, but I still can't seem to pinpoint the problem. I will pull the top carb and rebuild it and see what happens. I don't know how trash got past the pickup filter in the tank and the clear filter I installed in the engine. And how did it only clog the top carb? Just hoping I don't have a more serious problem with the block or reeds. Thanks for all the help so far everyone.

 

[DJ]

Re: Sneezing through top carb

Freeze,<br /><br />You probably don't have "junk" that got past your filters. It is probably old fuel/oil that varnished a jet. The top carb runs out and drains first.<br /><br />I would rebuild all of them, while you are at it.

 

[Freezebear]

Re: Sneezing through top carb

Ok, I managed to get home on time from work today and started tearing into the carbs. Took all 3 apart and checked. They are spotless. Noticed top carb had a little bit more fuel than the other 2 when drained. Found just a little bit of white debris in top carb bowl. Checked float height and hang on all. Found #3 carb float hang was 1/2" lower than #1 & #2. Adjusted so it is the same as the other 2. Inspected the reed valves from looking through the carb holes. All are shiny and when I crank the engine over while holding a piece of cardboard in front of the bores and they sucked in and did not blow the cardboard off. Now I'm really stumped.

 

[Bass Runner]

Re: Sneezing through top carb

There you go the white stuff is or has been water, some of it got past the needle and in the idle jet, thus the lean sneezing as you call it, when you pull the carb take the jet out and run a fine (copper) wire through it and i bet you find your gremlin, do not use steel wire for this it will scratch the jet and cause proplems.

 

[Freezebear]

Re: Sneezing through top carb

Wheew! Just got back in from wrestling the beast again. It won again, but I'm closer to understanding what's wrong with it. I now need details of the fastners used in the adjustment linkages. I believe that is what the trouble is now. There are discrepices between the pictures of them in the manual and and what I actually have. The 2 fasteners in question are the lower of 2 screws on the side by the throttle arm. It is the Idle Stop Screw. Mine has just a screw with no spring/nut mechanism like the top one which is the WOT Stop. The WOT Stop has a spring mechanism with a square nut and spring that sit in a square hole. The same is true with the Idle Timing Screw under the baseplate. It has a square nut and spring that fits in a square hole but doesn't sit right like the WOT Stop screw does. All the adjustment I can get out of it is around 8-10*ATDC When I manualy move the timing with the adjustment linkage disconnected, I can manage to get it to go down anywhere from 0-4*ATDC and can get it to run quietly at its lowest idle now 900RPM. I think I am doing something wrong in assembling the adjuster into the square hole of the timing adjuster. Any ideas? I am going to hardware tommorow and find a slightly longer screw and try to see if it will idle down and stay running. <br />What I have Done/Checked.<br />Idle Timing- 8-10 ATDC, spark check was good on all 3, all coils ohmmed identical, new wires and plugs.<br />Fuel System- Cleaned all 3 carbs and rebuilt. Thanks BassRunner for the tip about using copper wire. A single strand from a braided #10 copper wire worked great. Replaced entire internal fuel line system including fuel manifold connector. Plugged off VRO oil at the pump. Checked pump output under cranking RPM's. Carbs set at 2 turns out. Checked recirculation line and found it is open both ways and there is no check valve on a parts breakdown. Plugged it off with a cap right now while the silencer is off in case there is an internal check valve that has failed. And of course I used the curved wire ties for the small hoses and zipcrimps for the main lines. <br />Compression check is identical on all 3 at 115PSI with throttle plates open.<br />I sure learned a lot about my motor in the last 2 days. Danged boat motor!

 

[Freezebear]

Re: Sneezing through top carb

Ok I pulled the flywheel to look at the key and it was straight. The stator/ignition coil assembly is cracked and oozing potting compound. The smaller sensor coil assembly is not cracked and looks good. Question. Would a bad stator/charge coil make the engine lose time? I thought the sensor coil controlled the timing.

 

[Freezebear]

Re: Sneezing through top carb

Well, I don't know what else to do. Looks like I'm going to have to haul her off to the shop and let them look at it. Any advice before I break down and take her there?