1993 yamaha 225 surging

93yamaha225 · Feb 19, 2011

i have a 1993 yamaha 225. had it on the water the other day and was surging on the top end, also has a flat spot about 1/4 throttle, i had the carbs rebuilt by a local shop and also have tested the tps and the crank sensors, today i started the motor up on the water hose and its idleing rough and noticed that there was fuel leaking out of the holes in both fuel pumps, when it misses it spits fuel out of the holes, wondering if anyone could give me some advice on what to do?

SparkieBoat · Feb 19, 2011

Re: 1993 yamaha 225 surging

surging is usually fuel related..maybe a bad fuel line/connector..clogged fliter..clogged tank vent..maybe bad fuel pump/s ..one way to test tank/hose issues is to get a 6 gallon test tank with a brand new hose and connections..also try pumping the bulb while motor is surging..if it gets better then its a good indicator of a bad pump.

93yamaha225 · Feb 19, 2011

Re: 1993 yamaha 225 surging

i have tried to pump the bulb and didnt make a difference, but i was reading another thread about a prime starter, could that be causing all of this? and also the motor will stall out at idle, i started it on the hose today and it seems to be missing and idling rough then stalls out.

SparkieBoat · Feb 19, 2011

Re: 1993 yamaha 225 surging

I am not sure about the prime starter..I am not real familiar with big Yamahas..I was just listing general causes of surging..if it is missing and idling rough..could also be a spark issue..assuming that the carbs were done right ..I will say you need to do a spark test on each cylinder with a spark gap tester set at 7/16 gap..then you need to do a compression test on each cylinder..also replace any filters in the fuel lines. if you do not have a water fuel separator install one..get the biggest one for that motor, if you already have one replace the filter. I still would do the test tank trial I outlined above..be sure to use fresh fuel in the tank.

99yam40 · Feb 19, 2011

Re: 1993 yamaha 225 surging

If you are having fuel coming out of places it is not suppose to, then I would be looking hard at replacing the fuel pumps if that is where the fuel is leaking out of

boobie · Feb 19, 2011

Re: 1993 yamaha 225 surging

Start with the fuel pumps. Fuel could be leaking into the cyls on the pulse side of the pump.

93yamaha225 · Feb 20, 2011

Re: 1993 yamaha 225 surging

thanks for all your help guys, im going to get new fuel pumps this week and try that.will post results next weekend, again thanks alot

93yamaha225 · Apr 6, 2011

Re: 1993 yamaha 225 surging

ok guys, i have rebuilt the fuel pumps, and that fixed the flat spot but still surging on the top end, also rebuilt the prime starter

SparkieBoat · Apr 6, 2011

Re: 1993 yamaha 225 surging

I would continue to trouble shoot the motor..if it is still surging you still have some type of fuel issue..maybe running lean and that can be catastrophic

93yamaha225 · Apr 7, 2011

Re: 1993 yamaha 225 surging

i was going back over my fuel lines today and noticed that the nipple on the tank was only about a 1/4 inch nipple, i replaced all the fuel lines with 3/8 hose except from the fuel tank to the water separator, it only had 5/16 hose on it but i think now that i found this out im gonna get a 3/8 nipple and replace all of it with 3/8 fuel hose, could that have been my problem?

99yam40 · Apr 7, 2011

Re: 1993 yamaha 225 surging

Testing is the best way to go.
if there is a restriction , a fuel pressure/vacuum gauge will show it

1993 yamaha 225 surging

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