1996 Evinrude 150--sneeze at idle

[rreid01]

A little background first--this engine has plastic carbs and the bowls were leaking around a little metal bb in each bowl last fall. I took it to the shop to have the bowls replaced and the carbs cleaned. After I picked the boat up and put it in the water I found that it would not run off idle--apparently they didn't do the link and sync right. Took it back, they linked and sync'd the carbs, put it back in the water and it ran great. No evidence of a sneeze. However it was quite cold that day--probably 40 degrees or less.

Fast forward to the beginning of the summer. The boat is running good off idle, but will not run at idle once it comes off fast idle with sneezing itself to death. It's sneezing bad at fast idle as well. The bulb is also not staying hard, so I figure I will start by replacing the bulb. No help, still sneezing. My next step is to replace the fuel delivery hose, but I kind of doubt that is going to solve the problem. It does not look particularly bad.

I assume it must have an air leak somewhere that is causing the lean sneeze condition. If replacing the hose does not work, what is the next step? The carbs should be good. None of the fuel hoses under the hood seem bad. The cap on fuel filter is tight. I do see six small hoses running from fittings on the back of the block to each carb. From where they run I would not expect them to be vacuum, but I really don't know.

This sneezing is driving me crazy. Can anyone help?

 

[jonesg]

Re: 1996 Evinrude 150--sneeze at idle

Let it idle and put 2 fingers in each carb to see if the sneeze stops, you're basically choking each carb in turns. If you can't isolate it to carbs take a look at timing.
Also look for leaking fuel at all fittings that might let air in.
Any alarms?

 

[rreid01]

Re: 1996 Evinrude 150--sneeze at idle

I'll try that. I did try covering one carb at a time with my hand.

No alarms. I don't think it is getting hot, but I can let it warm up, take off the hood and see if any cylinders/banks are hotter than another.

I really don't seen any leaks with fuel delivery under the hood. I used the new bulb to pressurize and see no leaks whatsoever. Before, when the bowls were leaking you could see the gas running down into the lower engine cowl.

 

[rreid01]

Re: 1996 Evinrude 150--sneeze at idle

Also, what is the thinking behind the timing recommendation? And how do you change the timing on this motor?

thanks

 

[jonesg]

Re: 1996 Evinrude 150--sneeze at idle

Also, what is the thinking behind the timing recommendation? And how do you change the timing on this motor?

thanks

lean sneeze could be lean timing.
try this,
http://www.bbcboards.net/zerothread?id=357667

http://www.cdielectronics.com/downl...linder 1988-2000 185-250 HP (Quick-Start).pdf

What happens when you hit the choke as its sneezing.?
Do all the carb plates close completely at idle?
And try spraying some mixed fuel into each carb to make certain whether its a fuel restriction.
After it warms up shoot the heads with an infra red thermometer.
Check the recirculation hoses aren't leaking, the 6 little 1/4 inch hoses that run from ea carb to the block, if they're dripping they're leaking.
Also try spraying deep creep or wd40 around the carb gaskets etc, might be an air leak.