2003 Suzuki 150 idle issues

[Billfo]

I searched the forum for rough idle issues but was not able to find anything to "diagnosis from the beginning".

I have a 2003 Suzuki 150 2 stroke- starts fine. Idle is rough. Almost sounds like a timing issue but it runs great with just a little rpms. Idles at about 900rpms.
I ran the tank to empty, then filled with good premium fuel. I installed a fuel/water separator, with no change.
Where the big deal is, trying to get into my slip at the marina. When I drift in to dock in neutral, shift into forward or reverse and let the motor idle it will die 99% of the time.

Any obvious suggestions that maybe a common known issue?
Thanks.

[Solarman]

Have you looked at plugs? I'm also guessing this is an EFI (electronic fuel injection) motor?
The gear counting coil on the flywheel would be my next inspection.
You are talking about a 2 stroke?
You mention changing fuel, we're you running ethanol fuel previously? Still? Do you use any additive in each tank full?
You don't need to use high test fuel, just use marine fuel, and still use additive with each tank.

Good luck, post back.

[Harper]

Throttle valve sensor might need adjusting, or could also be dirty injectors. As Solarman said, no need for premium fuel, just make sure your oil tank and fuel system are clean.

[Billfo]

Thanks for your reply. I am an avg mechanic. IF I can "see" its broke- I can fix it. But I don't know how to troubleshoot much on an outboard.

Have you looked at plugs? I'm also guessing this is an EFI (electronic fuel injection) motor? YES
The gear counting coil on the flywheel would be my next inspection. Don't know how to check this.
You are talking about a 2 stroke? YESYou mention changing fuel, we're you running ethanol fuel previously? Still? Do you use any additive in each tank full? Been running marine fuel with Seafoam for the past year. Started having the problem when I filled with the Marinas winter left overs.
You don't need to use high test fuel, just use marine fuel, and still use additive with each tank.
Good luck, post back.

[Billfo]

Throttle valve sensor

Throttle valve sensor might need adjusting, or could also be dirty injectors. As Solarman said, no need for premium fuel, just make sure your oil tank and fuel system are clean.

Throttle valve sensor (is this something I can do myself if I research HOW to do it) ?

[Billfo]

Update !!!!!

Continuing my research a light bulb went on. Last season (was my first with this boat)- when I turned on the key to start motor- the "warning system would all light up and beep- then stop & lights go off- like I think it should on start up. It does NOT do that anymore like its disconnected. The last thing that was done to the boat in early winter was a shop guy fixed a fuel leak on the fuel filter connection, AND replaced the fuel level sending unit on the fuel tank AND I replaced the gas gauge since the sending unit still didn't show fuel in the tank.That is when the issues started right after that. When we put the boat back in the water the first thing we did was fill the tank.

So looks like I have a possibility of causes.
1) the warning system was disconnected by shop (maybe forgot to reconnect causing bad voltage reads someplace, but I don't know where that connection is)
2) Shop installed the wrong fuel sending unit- (results messing with voltage)
3) I screwed up an electrical connection at the gauges.

I searched the forum for rough idle issues but was not able to find anything to "diagnosis from the beginning".

I have a 2003 Suzuki 150 2 stroke- starts fine. Idle is rough. Almost sounds like a timing issue but it runs great with just a little rpms. Idles at about 900rpms.
I ran the tank to empty, then filled with good premium fuel. I installed a fuel/water separator, with no change.
Where the big deal is, trying to get into my slip at the marina. When I drift in to dock in neutral, shift into forward or reverse and let the motor idle it will die 99% of the time.

Any obvious suggestions that maybe a common known issue?
Thanks.

[Harper]

Continuing my research a light bulb went on. Last season (was my first with this boat)- when I turned on the key to start motor- the "warning system would all light up and beep- then stop & lights go off- like I think it should on start up. It does NOT do that anymore like its disconnected. The last thing that was done to the boat in early winter was a shop guy fixed a fuel leak on the fuel filter connection, AND replaced the fuel level sending unit on the fuel tank AND I replaced the gas gauge since the sending unit still didn't show fuel in the tank.That is when the issues started right after that. When we put the boat back in the water the first thing we did was fill the tank.

So looks like I have a possibility of causes.
1) the warning system was disconnected by shop (maybe forgot to reconnect causing bad voltage reads someplace, but I don't know where that connection is)
2) Shop installed the wrong fuel sending unit- (results messing with voltage)
3) I screwed up an electrical connection at the gauges.

I think we may be talking about two different issues here. On the lack of a system check prior to startup, I'd vote for #3. But I don't think that would cause your rough idle/stalling issues, although I'm not real sure of that, either.

The throttle position sensor is easy enough to adjust, just loosen two screws and pivot the sensor, but you need some diagnostic equipment to get it in the right position. Item #3 in attachment is the TPS. That diagnostic equipment might be something as simple as a digital auto-ranging voltmeter, but you still would need a service manual to see what the correct output voltage would be. does your boat idle long enough at times that you can give us your normal hot engine idle RPM?

[seaox230c]

Adjusting the tps is fairly strait forward...but you do need to make or buy the 3 wire breakout harness...there are other easier options to do first. first...run off a aux tank hooked up with new clean fuel....2nd you might have bad low pressure fuel pumps...mine had broken or missing check valves in both of them. NOTE...the rebuild kits do not contain the check valves...only the diaphragms and springs...does it run bad in idle ...not in gear or only in gear and idle...makes a difference