No Fuel to the Carbs

[Jerry476]

I have a perpetually hard starting 1996 Yamaha Waveraider (RA1100).

Replaced the plugs with no improvement. Had the carbs rebuilt last season with no improvement. So I took the fuel line off the outlet of the fuel pump and then cranked the engine to see if fuel was flowing to the carbs. No fuel was discharged from the line. The fuel filter was 3/4 full of fuel at the time. Does this mean the fuel pump is bad? Or is there another culprit?

Thanks for the help.

[Tony G]

Re: No Fuel to the Carbs

I,m not sure but most two stroke fuel pumps run on crank case pressure as the crank moves past the port that feeds the pump pressure. You may have a bad filter or if the carbs have accelerater pumps they may not be working, how does it run on the top end ? If it runs good once it starts the filter is ok, do the carbs have fuel in them ? use the choke it should start,,,tg look at the line that powers the fuel pump :) fuel pump could have some dirt in it or corrosion makeing the valves not seal,,,tg

[Jerry476]

Re: No Fuel to the Carbs

I haven't been able to get it started at all for the last week. When I prime it with some raw fuel to the arrestor, it will start and run just fine until that fuel is used up.

That is why I was thinking it might be the fuel pump.

[Tony G]

Re: No Fuel to the Carbs

sounds like the pump, take it apart and and see what's going on, not hard,,make sure all the lines are good, maybe something in the tank has fallen off, look at the tank and the supply first, pick up etc.,,,tg:)

Filter ?

[Madfish]

Re: No Fuel to the Carbs

You definitely have a fuel delivery issue if the ski starts and runs when you prime it with gas.

It would be very rare to have a "bad" fuel pump, especially if the carbs were just rebuilt last summer. The other guy is right, you wont see any fuel coming out of the disconnected gas line when you crank engine. I'm not too familiar with your ski, but most Mikuni carbs have an accelerator pump which shoots a little gas into carbs to get the engine started, and then vacuum from the engine takes over to pull gas from the tank and through the carbs. Was the accelerater pump diaphram replaced when the carbs were rebuilt? Parts for this do not come with standard carb rebuild kits.

My first guess would be that you have water in gas. All fuels have ethanol added, and ethanol attracts moisture from the air in your tank and causes condensation/water to form in the bottom of your tank and that can get into the carbs. Gas can spoil in as little as 60 days unless it is treated with a fuel stabilizer with ethanol treatment. You may also have some crap that has made it's way into the carbs and you may need to re-clean them. That happens. And one last thing, make sure the gas line and pulse line are not in the wrong locations.