Carbs didn't look dirty! Is this normal?

[johnm]

I've been having a problem with my envirunrude motor when engine is warm. Going from neutral into gear stalls the motor. When cold, it is fine. So I took the advise from this forum(and what a great forum this is!) and cleaned and rebuilt my carbs. After getting the rebuilt kit, I started to pull apart carbs. To my amazement, they looked very clean. All parts, gaskets and washers looked pretty new. Nothing looked dirty or blocked. Is this normal for fouled carbs? Nevertheless, I sprayed and soaked the carbs with carb cleaner and rebuilt them according to my manual. I have yet to test the boat. What I would like know know is, for fouled or dirty carbs that look clean, do you think a rebuild would make a difference? I'm doubting my time and effort will actually do anything.<br />I bought the boat about 3 months ago and don't know the history, although it did need a new water pump and sparks.

 

[ob]

Re: Carbs didn't look dirty! Is this normal?

JohnM,Bring us up to date with what motor you're working on.Stalling problem may also be carb sychronization out of adjustment and or idle mixture.Also a fouled carburetor could be something as minute as small particulates in idle ports or gummy deposit.It doesn't take much.

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

It's a 55HP 1979 Envinrude 2 stroke. Only stalls when engine warms up, ok when cold, giving me grey hairs. The carbs on this engine can't be adjusted.

 

[OBJ]

Re: Carbs didn't look dirty! Is this normal?

Hi johnm...what ob said and a little more. When is the last time you had a compression check? Are you sure the motor isn't running a higher than normal temp. or just overheating? Did this problem just crop up? Have you had any other problems with the engine?<br /><br />Geezz...I sound like a doctor!!<br /><br />OBJim

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

Mechanic checked out compression about a month ago and it is fine. The engine runs beautifully in every other regard when cold. But when warm, I get the stalling problem from neutral into gear. Planing along all goes well, cold or warm. Don't know if engine is heating up or not, how do I check and what can be done to fix it?

 

[OBJ]

Re: Carbs didn't look dirty! Is this normal?

Your engine runs best at a temp of 140 to 145. This being measured at the flat place on top of the engine just forward of the head. You can use temp sticks which melt a certain temp or use a good heat gun to check temp while running. Two things, one or the other, primarily go wrong when an engine overheats. The impeller wears out or just fails or the thermostat fails closed. But the more I think about your problem, and maybe ob will bear me out on this, I think you just got a low idle problem. Do you have a tach? Your engine should idle somewhere in the 650 to 750rpm range in gear. It will idle up slightly when out of gear. Check your manual for specks on this. Maybe all you need as ob said is the synchronization of timing and carb linkage adjusted. Or just a turn on the idle screw.<br /><br />OBJim

 

[Sand Bass]

Re: Carbs didn't look dirty! Is this normal?

JohnM, clean looking carbs can fool you. Your time was not wasted...especially not knowing when the last time they were rebuilt. It can make a difference!

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

Outboard Jim, I can't adjust the carbs on this engine(I am assuming you are talking about the carb linkage here) and I have played around with the idle screw to no avail. Idle screw adjusted enough so that engine purs like a cat, actually roars like a tiger. I don't think I'd want it going any faster though. I don't have a tach, but I will buy one and measure RPM's. Where do I attach tach? I am learning fast. Does heat gun run on batteries, I would like to test while out on water.<br /><br />If say, it wasn't my carbs, and linkage and timing what else could it be? I have changed all fuel lines. Getting a little ahead of myself I know, but preparing for the worst.

 

[mellowyellow]

Re: Carbs didn't look dirty! Is this normal?

here's a couple of possibilities:<br />1)float sticking causing flooding<br />tap on the bowl with but of screwdriver to unstick<br />2)fuel restriction or ventilation prob.<br />vent open? try a differnet tank and primer bulb if u can<br />3)kill switch grounding<br />think that model has a kill switch???<br />4)bad coil/wires.<br />make sure you have spark when it heats up.<br />run at night on muffs till hot and look for<br />any arcs from plug wires/coils etc.<br />of course I'm guessing....<br />good luck,<br />M.Y.

 

[Capt Ken]

Re: Carbs didn't look dirty! Is this normal?

Those older two cylinder engines had a very high compression ratio compared to other engines. The cylinders should be up in the 170-180 psi scale. Many times when a compression check is performed, the mechanic sees the normal 110-130 range and declares it good. I think when the engine has warmed up, the compression drops and causes your problems.

 

[OBJ]

Re: Carbs didn't look dirty! Is this normal?

JohnM...OEM service manual says engine should idle @1000 to 1100 rpms in neutral. In gear, 700 to 750 rpms. If you are going to check engine temp on the water, I would suggest temp sticks. These melt at a certain temp. I use a 125 & 163 stick. You can get a Tiny Tach, ( I think thats the name) to use. Check iboats store. I also noticed that your carbs have two idle orifices. Little pluggage here can cause your problem. Capt. Ken also makes another good point on compression. Try de-carbonizing the engine with tuner. Easy to do and can't hurt.<br /><br />OBJim

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

Excuse my ignorance, how do I decarbonize my engine with tuner? Is there anything I can do about the compression? I suppose I can test compression myself when engine warms up. I'm buying myself a tune up kit with a compression gauge, so that should do the trick. Check it on the boat ramp after a session. If my compression is out a fair bit between both cylinders, can I fix it or is this major and costly work to be done by a mechanic?<br /><br />Also those two idle orifices you mentioned OutboardJim, can I adjust these and will they help my cause. Where are they located? Thanks.

 

[ob]

Re: Carbs didn't look dirty! Is this normal?

The idle orifices are located behind a cover screw near the bottom left face of carb throat.The intermediate orifices are under cover screw on top of carb face.They are not adjustable..I thought you already cleaned carb.You also need to insure pickup tube in carb bowl is clear.A manual specific to your motor would be an asset if you are not familiar with procedure for overhaul.

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

Yes, I have cleaned the carbs and do have a manual, but manual can sometimes be so non-specific that at times can be confusing. Sorry for ignorant questions, I am just a little unfamiliar with the terms used on this site as I am a beginner keen to learn.

 

[wilde1j]

Re: Carbs didn't look dirty! Is this normal?

Save yourself the expense and trouble of getting something special to measure temperature. You should be able to put your hand on the top of the block w/o getting burned (most hot water heaters are set for ~ 140 F). I expect somewhat higher than OBJim suggests ... I expect 155 to 160 on most of the larger OMC OB's. Still not high enough to burn if you touch it.<br /><br />I would add that to test for idle RPM that yoyu have the boat in the water and not on muffs. Most motors will idle much higher on muffs due to lack of back pressure. Good luck.

 

[ob]

Re: Carbs didn't look dirty! Is this normal?

We all have to start somewhere.What I am attempting to concentrate on is what I feel your stalling problem is.<br />With all due respect if you have not removed and inspected idle or intermediate orifices as of yet I would not consider the carb clean.<br />These orifices and ports on your carbs are extremely critically sized and the symptom of stalling from neutral to gear challenges not only the efficiecy of the carbs porting but the synchronization of its flaps opening at the proper time in relation to the ignition timing, which fluctuates with throttle application.<br />An integral part of troubleshooting an engine symptom is through a process of elimination.That's why if one component isn't known to be in operating order diagnosing any further becomes a crap shoot.<br />Carb restrictions and linkages even slightly out of synch are a "common" problem associated with operational glitches in a 2 stroke outboard.<br />If you want to begin your procedure by performing a compression test you can simply warm engine while running on hose before obtaining readings.<br />Decarb products are sold under many names by different manufacturers and will aid in the breaking down of carbon deposits in piston ring grooves and piston heads.This procedure is recommended to perform seasonally or in relation to engine run time or sustained low speed operation.The products can be introduced by spraying into carb throats while running or directly into cylinders via sparkplug holes.Follow the products instructions for dosing.I recommend obtaining the ones sold through the dealer. <br /> Here's an exploded view of 1980 55hp carb you can check out to locate components.Pay particular attention to # 9,35,& 37 on disassembly and inspection.They are prone to collecting gummy deposits which retsrict fuel flow.You'll need a narrow diameter screw driver to remove orifices.<br />Get the carb servicing complete and post back and someone can assist you in checking linkage and flaps for adjustment.<br /><br />carb pic

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

Nice diagram OB. This will help. I just went out and bought myself a timing gun and a compression kit so that I can try out the recommendations people have offered. Many thanks and I will keep you posted.

 

[rickdb1boat]

Re: Carbs didn't look dirty! Is this normal?

John,<br />Good advice by OB and Wildeone! Just put your hand on the head to see if it's overheating. I tend to go with OB on the linkage or Carbs being clogged up a bit. If it runs good except for when you take off, I'm betting on the linkage adjustment. If you have not messed with the timing adjustment screws, I doubt that is a problem. Sync the Carbs simply means adjusting the Carbs so that they both open at the same time, and in relation to the timing. Clean the Carbs again and do a lync and sync and you should be good to go!

 

[Big Al1]

Re: Carbs didn't look dirty! Is this normal?

Sounds like it could just be the idle adjustment on the carb. Sound like you are just running too lean of gas / air. My old 6hp did the same thing and I rebuilt the carburetor and adjusted it just right and it stopped stalling when I put it in gear. My brand new Mercury 15hp is doing this when cold because I have 25:1 gas/oil to break it in. It is too lean. Turn the idle adjustment needle all the way in and back out 1 to 1.5 turns. Then go from there with small adjustments. All carbs in your egine must be adjusted the same!

 

[johnm]

Re: Carbs didn't look dirty! Is this normal?

The results have not been good. I still have the same problem as above and please, please note that my carbs do not have adjustable screws and I get stalling problems only after engine warms up(about 15-20 minutes or so running). Here is what I have done. Pulled carbs apart again and soaked them overnight. Should I be soaking for longer? Put together again and did the lync and Sync as well(I know what this is now ). Timing is spot on, waited till dark so I could see the strobe, neighbours were'nt too happy! Revs are also spot on on idle and in gear after adjusting idle screw ever so slightly, according to manual. Interesting note, rechecked compression when engine warmed up. When cold, 1st cylinder reads 165 psi, 2nd cyliner reads 150 psi. After 15 minutes or so with engine running in idle in a TEST tank, I recheked compression. 1st cyliner read 135 psi, 2nd cylinder read 120 psi. Compression has dropped considerably when engine warm. Put into gear after engine warms, after about 1 minute engine stalls. Restart engine straight away, put into gear, engine stalls after 10 seconds and does this again and again until engine cools down again. In a previous post, Capt Ken and OutboardJim suggest that the compression reduction could be causing my problems. Note that all tests carried out have been in a test tank. What next?