Carbs leaking

M

menacer

Member
I have a 1990 Evinrude 155 commercial engine on my V 20 and maybe someone here can set me strait. I had the 3 carbs cleaned this week and the motor runs pretty good it can only get 4500 rpms, the same as before the cleaning . I would like to get at least 5000 but I can live with it. My main issue is when I tilt the engine all the way up, its almost horizonal and the carbs leak or empty out into the carb cover. When I tilt it back down the gas drains from the cover into the cowling base and down the outside of the shaft housing. I do not smell fuel when its in the down position out on the water so its not leaking when in use just when I have to tilt all the way up.
 
I use to get that from my old merc, leaking while up?? Never did figure it out??

What prop you using?? Wrong prop won't allow you to get rpm's up or down, depending what you using

a little more info please. Skools might see this he is the rwsident OMC God, although there are a few others as well!!
 
alot of mercs do that while tilted up.....and Menacer, your floats may be out of adjustment, just a hunch, wait for resident OMC motorhead "Skools out" ;)
 
Macojoe, Ive tried 15x 15 ss a 15x17 aluminum and a 14 1/4x17 ss stiletto . No matter which prop I try , 4500 rpm is max. The carbs are fully opening , the timing is dead on and advancing ,and compression is good on all cylinders. I even tried raising the motor a hole with no improvement . I've racked my brain ( all 2 brain cells ) trying to get the rpm's up.
 
I'm almost wanting to agree with phester. Seems we had one that did that and the needle seat was missing or damaged or the float was misaligned, I can't remember. ???
 
Update, I pulled the cover off the front of the carbs , pumped the ball, and with the motor facing strait I tilted it all the way up and no leak. Then I turned the motor to one side and that's when it leaked. I guess its an over flow that's normal but I still need to know for sure. Now I have a rpm issue I need to address. I'll try the shop tach next and post my results.
 
If you don't mind doing it, remove the plugs to the high speed jets and spray carb cleaner thru each jet. Too many people have told of the same thing about having the carbs cleaned and for some reason most mechanics don't bother doing this.
 
And I do remember an 18hp I had that wouldn't get up to full rpm. Come to find out when the carb was rebuilt they left out the o-ring between the bowl and carb. :P
 
Did the so called commercial engines have a restrictor on them preventing RPM advance or retarding advance. I know some commercial equipment you can rent have those on them. Just a thought?
Also can you rev the engine out of gear (in the water) to above that RPM. If it does not go above like that then I think you have a timing issue.
Also what is the condition of the lower unit, if it is under load and won't reach the desired range but will do it with no load the lower unit can be causing the problem with a lube or bearing problem.
In the carbs you can also have a restrictor plate preventing fuel flow above a certain CFM
Just some thoughts, have you ever gotten the manual on those commercial engines, if there was any restrictor type things it should be noted in the shop manual.
The reason I think it might be related to something of that nature is you changed the props pretty substantially and saw no changes in RPM's. I never heard of that ???
 
Wish Pipe Dream would jump in here...he operated one of those motors for quite a while...Hey Pipe...what's goin' on here??...any ideas??...
 
Don't believe I can be of much help here, sorry.

I never had an issue with fuel leakage when I trimmed the engine out of the water. You mentioned tilting it straight up -- I believe mine was always turned all the way to starboard when I brought it up, it just seemed to naturally go that way. Have anything to do with it? I don't know.

As far as RPMs, it's been a few years and I never wrote down what kind of revs I was getting at speeds, and so on. But I don't believe I ever got her to 5000, only high 4s.

I can tell you that that 155 was a really durable engine. We got a LOT of service out of it, and it just wouldn't die. For years the guys at the marina called it the "miracle motor," among other things. ::)
 
I'll take a stab at the lack of RPM's. I think the larger gear case on the commercials plays into the equation. i don't know if its the bigger gears or perhaps the additional drag going through the water. ??? Just a couple of things to think about.

Other than what I posted above, I know some guys have gotten a few more RPM's after a decarb. This may do the trick since the motor hasnt been able to get to the top end of its RPM range it may be all carboned up.
 
O K , this is what I've tried since the last post. I've replaced all the fuel lines 3/8" from the tank to the VRO. Installed a new VRO and ran a heavy concentration 4 to1 of Sea foam through the engine. Had to readjust the idle after the Sea foam treatment because the idle went up to 1400 rpm's. And I also replaced the water pump. I'll take her out Saturday on the Delaware bay and open her up. Hopefully I'll get to the 5000 range and I'll be happy. If this doesn't work maybe I should change the lower gear case from the V8 to a V6. I'll keep you posted on the results. In the mean time any and all suggestions are welcome.

Dennis
 
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