1990 yamaha wave runner wont start

[theors02]

my 1990 wave runner wont start my fuel pump is getting fuel to the carb, but wont start but if i put fuel in the cylinder it will start. turns over strong. have spark, fuel to carb, new diaphram new plugs, reeds good, no idea where to go next good compression. ???

 

[seadoosnipe]

Start problems...

my 1990 wave runner wont start my fuel pump is getting fuel to the carb, but wont start but if i put fuel in the cylinder it will start. turns over strong. have spark, fuel to carb, new diaphram new plugs, reeds good, no idea where to go next good compression. ???

I've owned the earlier Yamaha's in the past. They are a really simple motor to work on. I had the 500 and 650 motors.

Your solution should be fairly simple... You say you can remove the plugs, pour a bit of fuel into the jugs, then get a start. I'll assume that as soon as you burn off the gas, it goes dead.

Your problem is going to lie in your carb(s). You state you have fuel up to the carbs. That's good. So, you can be assured that you have fuel supply. This only leaves one area that can be your hold up, the carb(s).

Your engine pulls fuel into the enigne via a manifold pressure, which is actually a vacuum. Are you trying to run the motor without the flame arrestor on. If so, you have to have this on to create a restriction. Try to cover the air intake with a plastic bag and see if you can draw fuel into the enigne. If you hear a start, quickly remove the plastic bag from your air intake.

From all you've stated, your problem can be nothing more than the carbs delivery into the engine........

 

[Dr Honda]

From all you've stated, your problem can be nothing more than the carbs delivery into the engine........

:agree: 100%


Just because you have a new diaphragm doesn't mean the carb is working. Pull it apart, clean everything, blow out the passages with compressed air, and verify that all the little ports are open.

 

[theors02]

Just giving you all the info and the plastic bag didn't work any other ideas

 

[Dennis]

Put your hand over the carb while cranking the engine. If you feel air huffing back at your hand then your reeds are bad. Wouldn't surprize me a bit on a 20 year old engine.

DAWG

 

[Kanine]

Hey I am have a similar problem I rebuilt and cleaned the carb, put it back on put needles in back to what they were have lots of spark and compression but will not start I also primed the fuel pump.