Mercury question

winni for fun · 06-10-2009, 08:50 PM

I have 1999 twin 150 HP Mercury Optimax on my boat, and have had some trouble with the throttles. The port motor would run at significantly higher RPM, even though the throttle was behind the other motor. As a result the check engine light would come on and an alarm would sound. A diagnostic was run at the marina, and I was told it was a problem with the Throttle Position Sensors. Just curious if anyone else has had a similar problem, and if replacing the sensors took care of the problem.

Seeker · 06-11-2009, 12:41 PM

Yes and no.
No, I don't have twins.
Yes, I have a 99 135 Optimax that had similar problems to yours a couple years ago. Diagnostics said replace a throttle position sensor. Did that, same problem. Also had to replace the second sensor which eliminated problem. $$$
A slight surging problem has occured which just might be a little water, haven't checked out yet.

cowisl · 06-11-2009, 02:22 PM

Call Dave Rossetti. 603 393 5658 he will figure it out for you

mastercraft · 06-12-2009, 11:12 AM

yeah call Dave Rossetti 603 393 5658

06-10-2009, 08:50 PM	#1
winni for fun Junior Member Join Date: May 2009 Posts: 9 Thanks: 0 Thanked 0 Times in 0 Posts	Mercury question I have 1999 twin 150 HP Mercury Optimax on my boat, and have had some trouble with the throttles. The port motor would run at significantly higher RPM, even though the throttle was behind the other motor. As a result the check engine light would come on and an alarm would sound. A diagnostic was run at the marina, and I was told it was a problem with the Throttle Position Sensors. Just curious if anyone else has had a similar problem, and if replacing the sensors took care of the problem.

06-11-2009, 12:41 PM	#2
Seeker Senior Member Join Date: Nov 2007 Location: Effingham Posts: 408 Thanks: 37 Thanked 19 Times in 15 Posts	Yes and no. No, I don't have twins. Yes, I have a 99 135 Optimax that had similar problems to yours a couple years ago. Diagnostics said replace a throttle position sensor. Did that, same problem. Also had to replace the second sensor which eliminated problem. $$$ A slight surging problem has occured which just might be a little water, haven't checked out yet.

06-11-2009, 02:22 PM	#3
cowisl Senior Member Join Date: Jan 2005 Location: Cow Island Posts: 167 Thanks: 6 Thanked 20 Times in 12 Posts	Call Dave Rossetti. 603 393 5658 he will figure it out for you

06-12-2009, 11:12 AM	#4
mastercraft Junior Member Join Date: Feb 2009 Posts: 11 Thanks: 1 Thanked 8 Times in 2 Posts	yeah call Dave Rossetti 603 393 5658