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2005 Optimax "Thirsty for fuel" over 200 RPMs
Rising Tides	#1  Posted on 06/22/19 - 8:42 AM
Member Posts: 15 Comments: 0 Joined: 05/25/17	I have a 2005 Optimax on my 190 Outrage. Engine only has 230 hours on it. Starts fine, idles great. Once I get to 1500 - 2000 rpms is starts bucking likes its not getting fuel. Plugs have been changed, Filters have been changed. Fuel is not contaminated. No sensors are going off and I had a merc mechanic put the testing machine on and it says all systems are fine. Any ideas? already missed 1/3 of the season. Thanks to all who respond.
Phil T	#2  Posted on 06/22/19 - 8:51 AM
Administrator Personal Page Personal Album Project Albums Posts: 7043 Comments: 6 Joined: 03/26/05	What happens when you pump the fuel bulb when it starts bucking? If it helps, could be a diaphram or failing fuel pump. 1992 Outrage 17 I 2019 E-TEC 90, Viper 17 2+ 2018 Load Rite Elite 18280096VT
Rising Tides	#3  Posted on 06/22/19 - 10:26 AM
Member Posts: 15 Comments: 0 Joined: 05/25/17	We just disconnected the fuel line and ran the engine on new gas out of a canister. Ran like a charm at high rpms. The engine is not the issue it seems. Potential 3things this could be: 1) Bad Gas (unlikely as its 75% new gas this spring 2) Its not sucking hard enough to draw from the tank 3) something else Where is the diaphram on this boat Are you referring to the fuel pump on the side of the engine? We are an army working on this right now. Thanks
Phil T	#4  Posted on 06/22/19 - 10:31 AM
Administrator Personal Page Personal Album Project Albums Posts: 7043 Comments: 6 Joined: 03/26/05	Back up a step. Is the original tank vented? If restricted it can distort the line and restrict flow. Presume you are testing engine with a load and not on muffs or reving in neutral. 1992 Outrage 17 I 2019 E-TEC 90, Viper 17 2+ 2018 Load Rite Elite 18280096VT
Rising Tides	#5  Posted on 06/22/19 - 10:45 AM
Member Posts: 15 Comments: 0 Joined: 05/25/17	on land on muffs Just removed fill cap will put in gear and rpm up no problem there we will relaunch and test under load. will have someone on board to push bulb if needed. pumped out bottom of gas tank no water found. more to come
Rising Tides	#6  Posted on 06/22/19 - 12:32 PM
Member Posts: 15 Comments: 0 Joined: 05/25/17	In water test results Used a 5 gallon auxillary tank attached to boat engine. Still have pump ball in line. We get under way, 2000 rpm engine starts to break up severely. One person pumping ball and one person driving and no better even with ball hard. We now believe the issue is in the engine while under load. Please guide us to our next step. Its not the fuel tank, its not fuel cap, as they have been bypassed. TY
tedious	#7  Posted on 06/24/19 - 5:10 AM
Member Personal Page Posts: 1072 Comments: 2 Joined: 09/07/08	The Optimax is a complicated, first generation direct injected motor. As a first step, I would make sure any and all routine maintenance has been done, especially replacing any internal filters and cleaning internal tanks. If the problem persists, next step would be to test the output of the fuel pumps - most of these types of motors have a lift pump to get the gas to the motor, and a high pressure pump to drive the actual injection, but I have no idea how that works in an Optimax. I think your best bet would be to find a mechanic who knows the Optimax inside and out. Edited by tedious on 06/24/19 - 5:10 AM
dontate	#8  Posted on 06/24/19 - 6:15 PM
Member Posts: 15 Comments: 0 Joined: 07/16/16	It sounds like you have eliminated the fuel system as the cause. I agree if it is in the motor have a good mechanic check it out as the older injection systems are a bit more complicated. One thing to eliminate is any gray color flexible fuel line if present. The line material is famous for delaminating and collapsing internally causing fuel starvation at higher RPM. Good luck solving an aggravating issue to say the least!
Joe Kriz	#9  Posted on 06/24/19 - 6:31 PM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	Rising Tides wrote: In water test results Used a 5 gallon auxiliary tank attached to boat engine. Still have pump ball in line. What pump ball did you use? The original one on the boat? When was the last time you changed the fuel line a bump ball above the deck? 2005 to 2019 should have new fuel line and fuel bulb replaced. If they haven't been replaced recently, it is cheap preventive maintenance.