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1998 Mercury Optimax 135 stalling
REK3	#1  Posted on 08/12/10 - 6:26 PM
Member Posts: 12 Comments: 0 Joined: 08/11/09	I have a 1998 Mercury Optimax 135 that has been stalling. I seems to be a fuel supply problem. Engine starts and runs good. On one outing the the engine sputter a few times. On my most recent outtings I am able to get the boat up on plane and it runs for 2-3 minutes, then engine begins to sputter and spurt. Eventually it stalls and won't restart. I then pump the primer bulb and the engine will restart and runs fine. Once running, the engine then sputters at higher rpms. It has been running smooth at mid rpms. Does anyone have thoughts. I am on vacation with the boat so I have some limitation to repair resources.
Mark Finkenstaedt	#2  Posted on 08/12/10 - 7:21 PM
Member Personal Page Posts: 195 Comments: 4 Joined: 08/20/08	I am definitely not the expert just the bitter user. My 2001 Optimax had a stalling problem when in idle but was fine running but probably not for long. The dealer wasted a whole lot of time and money working on the reed valves only to find it was a bad #6 cylinder. Solution a new engine. Just describing a stalling problem with an Optimax. I hope it's a cheap fix and you continue having a wonderful holiday. Now the experts will chime in... 2001 18' Dauntless - 150HP 2010 E-TEC
REK3	#3  Posted on 08/13/10 - 4:58 AM
Member Posts: 12 Comments: 0 Joined: 08/11/09	Mark- Thank you for the feedback. I hope it is a simpler solution than a new engine! Anyone else have further thoughts?
MW	#4  Posted on 08/13/10 - 5:05 AM
Member Personal Page Posts: 1827 Comments: 10 Joined: 01/08/06	I'm going to guess "Pin hole" in Fuel pump Diaphragm. Matt
REK3	#5  Posted on 08/13/10 - 5:02 PM
Member Posts: 12 Comments: 0 Joined: 08/11/09	More information. Engine ran great today, for about 45 minutes of running. Then it stalled. I squeezed the primer a few times and it re-started. Then ran good. Stopped for lunch and beach time. 2 hours later it started fine. Then after 3-5 minutes of idling then up on plane and engine die. Again. after numerous primer attempts engine restarted and ran good for the hour back to the ramp. I am now thinking some sort of vapor lock is occurring. Any thoughts along that line?
Royboy	#6  Posted on 08/13/10 - 6:25 PM
Member Personal Page Posts: 127 Comments: 2 Joined: 04/23/07	Check the vent and make sure nothing has built a home in it. Also might replace your priming blub and fuel hose from the moisture seperator to the engine. Last resort might be a fuel pump. Priming before starting the first time you take it out for the day will save your pump. It sounds like one of two things is happening. Either you are sucking air into the fuel pump from a leak and it is cavitating, or you are sucking all of the air out of the tank and starving the pump. Think three is a bad pump.
Mtinrunner	#7  Posted on 09/08/10 - 3:43 PM
Member Posts: 2 Comments: 0 Joined: 09/08/10	Sounds similar to what my Opti 135 was doing. After bringing it back several times the problem didn't show until they put it under heavy load. The low pressure fuel pump which is cooled by the gas was over heating. pump was $230 at the dealer and $99 on EBay. I even bought an extra. Switched it out myself. I hope you figured it out by now.