2002 Yamaha 150 RPM issues

[tminoughan]

I just bought a boat with a 2002 Yamaha 150 2 stroke. First ran it and it got to 4000 rpm then dropped to 2100 the rest of the trip went back and checked the oil levels etc all were fine. Thought there might be water in the gas so I changed the separator filter and drained the carbs and hooked up a clean fuel source. Went out again and all was good at 3800-4000 rpm and then on the way back it dropped again to 2300 the rest of the way in? Is there a possible sensor issue, not sure this is the first Yamaha I have ever owned?
Any direction would be helpful.
Tim

[rodbolt17]

sorry
sounds like ya bought a pig in a poke.
but it is yours now.

test the alarm system.
pull the stop lanyard, briefly crank the engine.
did the alarm sound?

what type of tachometer do you have ?

a friend of mine just bought a pig n a poke. only his has a 3.0 mercrusier that not only overheats but has water in the oil and water on cyl 2&3.
moral of the story, ALWAYS have a professional Engine survey BEFORE buying a boat.

[tminoughan]

2002 Yamaha 150 RPM issues

Hi Rodbolt17,
Tries the recommended tests.
Pulled the Stop Lanyard and tried to start, No alarm?
The tach is a Yamaha. Digital with oil and temp and tilt/trim indicators.
Again any insight would be greatly appreciated.
Tim

[Psalm 99]

RPM Problem

I had much the same problem last year. My engine is a Yamaha 150 2-cycle (2004) which I bought used. The fix ended up being pretty simple: Bad connection thru a ground wire. This was intermittent like your problem but with a difference: I'd be going along fine between 2300 - 3200 rpm when the engine would revert to about 1600. No alarms nor miss firing. Left throttle set for about 3200 rpm and headed home. Engine would periodically surge back to throttle setting, sometimes for a few minutes and sometimes just for seconds. Found out that this happens automatically when engine senses that something is amiss and is called something like 'Safe Mode'. I'd also check your fuel pumps. Lastly, engine will run even with just two cylinders firing. You can get home at about 1600 rpm like this. Four cylinders give you max. 2300 rpm. All six give of course full power. Could be you simply have a fouled carb. Pretty common with a used engine which may have sat for an extended period. Lots of trouble with my used engine but the advice from this site was extremely helpful and the engine works great now.

[99yam40]

Hi Rodbolt17,
Tries the recommended tests.
Pulled the Stop Lanyard and tried to start, No alarm?
The tach is a Yamaha. Digital with oil and temp and tilt/trim indicators.
Again any insight would be greatly appreciated.
Tim

Fix the alarm 1st
and then pay attention to what the gauges are telling you when the problem occurs

[rodbolt17]

this engine should NOT try to start with the lanyard out AND should give an alarm cranking with the lanyard out.

fix this issue first.

then it is time to test compression and spark.
if they pass it will be time to go through the fuel system.

[tminoughan]

All,
Thanks I will work on figuring out the alarm problem first.

[tminoughan]

Hi
Corrected the alarm, changed the spark plugs and the compression was between 119-125. Found some water in the fuel so I drained and changed the water separator filter. Still having the RMP issue? 4000 down to 3200 then down to 2300 and stalling at low idle?

[TownsendsFJR1300]

Drain the carb bowls. Pump the primer bulb too while the bowl screw is out...

I'd catch what comes out (I use a CLEAN tuna fish can) so you know what your dealing with..

I suspect your carbs need cleaning... Especially as you don't know how long the engine sat...

All JETS must come out and VISUALLY inspected to be clear..


http://www.boats.net/parts/search/Ya...TOR/parts.html

[rodbolt17]

does it even have carbs?
all we think we know is its a two stroke from about 2002.

VZ Z SX S VX what are we discussing?

[tminoughan]

Hi
Did that with the carbs. They might just need a good cleaning?
Model # 150TXRZ.
Had it out this morning and it started rough but then accelerated and ran fine. When I got back to the dock was sputtering at low idle and neutral.
Thanks again for the info.

[TownsendsFJR1300]

Are you located in the US?

I can't find an '02 150 TXRZ under the parts section.

(I gather if you drained the carbs, its got carbs).

[99yam40]

Hi
Corrected the alarm, changed the spark plugs and the compression was between 119-125. Found some water in the fuel so I drained and changed the water separator filter. Still having the RMP issue? 4000 down to 3200 then down to 2300 and stalling at low idle?

What did you do to correct the alarm and make sure it functions properly now?

If you found more water in the separator this time it means there is water in the tank and that needs to be drained and cleaned up.

if you have been using any ethanol fuel, then the water and ethanol has dropped out of the fuel and it is bad fuel now, get rid of it

[tminoughan]

Yes, I'm in NJ, The model number came from the sticker on the manual. The alarm issues was my fault once the lanyard was removed the alarm did sound when I tried to start.
Have used it a couple of times this weekend and it is getting better, still some stalling at low idle but the RPMs seem to be ok and not dropping like it was before.
Thanks for all the suggestions
Tim

[99yam40]

Just for your info the Z says it is a 2001 model

Make sure you look at the sticker on the motor to make sure that model # there matches what you are seeing in the manual