Idle for a 1990 Evinrude 150xp?

[waterinthefuel]

I was told it's 900-1000 rpm. Our tach is indicating 1200, but the mechanic said the tach is about 200 rpm off. We tried to idle it down using the idle screw, and if anything the idle speed went up. It just seems to be running too fast. It throws the boat around when you shift it, and it's hard to dock because its going so fast. The boat is a 18 foot fish and ski, only rated for a 150 and it does have a 4 blade prop.<br /><br />Can anybody help me?

 

[Joe Reeves]

Re: Idle for a 1990 Evinrude 150xp?

The tachometer should have a dial on the back of it which should be set to number six (6).<br /><br />If indeed the tach is faulty or one that is not suitable for your engine, replace it.<br /><br />On a flushette, if you have a 20" shaft engine, the idle rpm should be set at 1000 rpm. If the engine is a 25" shaft model, set the idle to 1200 rpm. When in the water, the idle will drop to a normal rpm due to exhaust back pressure.<br /><br />Should your engine not run properly at idle when in the water after setting the idle as above, there would have to be a problem with the engine such as.... improperly adjusted linkages, synchronization misadjustments, compression, weak or non existent spark on one or more cylinders, something of that nature.

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Well that makes sense. While she's in the water she idles at 1000, roughly (meaning I don't know if it's exact). Is this causing lower unit damage to shift at this speed?<br /><br />Also, this engine "sneezes" for lack of a better word, when idling. It seems to sneeze constantly, whereas my little 28 will only sneeze when cold. Any suggestions?<br /><br />Getting to this tach is like getting to Mars. It's buried so deep in my dash that getting to it is like planning a mission to the red planet! LOL

 

[walleyehed]

Re: Idle for a 1990 Evinrude 150xp?

The "sneeze" is a lean condition in the idle circut...It might be time for carb O/H's.....

 

[seahorse5]

Re: Idle for a 1990 Evinrude 150xp?

Walleyehed is correct that a "sneeze" is from lean idle circuit, and it can also be from one or more of the following:<br />engine not warming up - thermostats<br />throttle plates not completely closed - sync. and link<br />leaking side covers in carb<br />wrong idle jets<br />reeds, or more likely, reed box gasket torn

 

[Joe Reeves]

Re: Idle for a 1990 Evinrude 150xp?

With the carburetor face plate removed, and with the engine running at an idle, stick two fingers into the carburetor throats (one carb at a time of course). This will act as an individual choke which will enrichen the fuel mixture for that particular cylinder.<br /><br />When you do this to a carburetor and the sneezing ceases, you have found the carburetor that is no doubt fouled and is causing the lean condition.<br /><br />Apparently your mechanic is simply increasing the throttle setting rather than diagnosing and correcting the cause. Shifting at a high rpm does cause stress on the shifting components and the driveshaft.

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Well the mechanic brought it down from 1000 to 900, or so he said. It still felt fast and made alot of noise when being shifted, so me and my father attempted to idle it down using the idle screw. We couldn't get it to go down. In fact, even after we put the screw back where it was when we started, the RPMs are back to 1000 and our problem is even worse.<br /><br />The big issue isn't the sneezing, it's the idle speed. I wish someone could give us instructions on adjusting the idle speed. If the idle screw does nothing, what else can be done?

 

[Cricket Too]

Re: Idle for a 1990 Evinrude 150xp?

If one or more of your carbs is running lean in the idle circuit it will cause your motor to idle higher, and the setting will not work properly because it is meant to set a properly running carb. You need to find the carb or carbs that are sneezing and fix them, your better off just rebuilding all of them and taking care of the initial problem, the carb setting is not your problem, a lean condition is your problem. After you fix the carbs you can adjust the idle properly. Good Luck.

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Is the idle adjustment on the carb, or is it that silver fine-thread screw on the left side of the engine, looking at it from inside the boat? I was told it's the big screw. If it is, how is it going to adjust the idle speed? The screw is nowhere near the carbs.

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Can I assume nobody knows?

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

bump

 

[Joe Reeves]

Re: Idle for a 1990 Evinrude 150xp?

No, you cannot assume that nobody knows. However I would suggest strongly that you purchase a service manual for that engine, then check and rework the carburetors as mentioned above. It's going to be impossible to set the idle properly while the engine is running lean (sneezing).<br /><br />Not having the book in front of me, I'm assuming the engine is a crossflow engine. If so, you can set the idle rpm by backing the mechanical idle stop screw away from the casting, then set the idle with the threaded trunion on the throttle cable, then screw the idle stop screw in just until it contacts the casting.

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Joe, you da man. We have a service manual for it. It says VERY little about adjusting the idle. The manual is where I figured out the idle screw is on the side of the engine. Thank you so much for the info!

 

[Hooty]

Re: Idle for a 1990 Evinrude 150xp?

W.I.T.F!<br />You mentioned it "made a lot of noise when being shifted". When shifting, do not ease it into gear and make that grinding noise. Cram it into gear with authority! <br /><br />c/6<br />Hooty

 

[waterinthefuel]

Re: Idle for a 1990 Evinrude 150xp?

Thanks, but I knew this already. I hear people grinding them into gear all the time. Sends chills down my spine. By "alot of noise", I simply meant a loud "clunk" due to the high idle.