Seadoo Challenger 2000 wont start

[Ukranian20]

Got a Sea Doo Challenger 2000 with the mercury m2 240 EFI that won't fire up. From what I can tell the problem seems to be coming from the vapor seperator. Fuel is getting through the fuel lines up until its supposed to enter the vapor seperator. Took apart the vapor seperator cleaned the whole thing with starting fluid and made sure the float was not sticking. Fuel pump also seems to be working as well just no fuel entering the vapor seperator. I also left some fuel in the vapor seperator after putting it back together. Started it back up and it ran for about 25 seconds before it died. Anyone got any ideas? Thanks!

 

[xlonewolf1967]

a quote from dr. Honda

You have 3 fuel pumps in the boat. Starting from the engine to the tank...

1) In the Vapor tank, there is a high pressure pump. It supplies the EFI rail with 36 psi. There is a regulator that returns extra fuel back to the tank. This system is like a toilet tank. The high pressure pump only makes high pressure... and has nothing to do with getting fuel into that tank. And, like a toilet, there is a float, and a valve to regulate the level in the tank. Because of this... you need pressure on the hose to feed the tank.

2) The square diaphragm pump on the block. This is your main fuel pump. It's 100% mechanical. On the back side... there is 2 vacuum ports that are open to the inside of the engine. These ports push and pull the diaphragm, and in turn... with the check valves, pumps the fuel from the tank, to the vapor tank. So... when you put it back on... make sure that the gasket is on the right way, and that it is sealed... AND... that you don't accidentally plug the holes with sealant.

The beauty of this type of pump is... that when it's full, and the diaphragm can't move... it simply stops pumping. BUT... if the lines are low/empty... it can move A LOT of volume. So... it's low pressure, with variable volume... and doesn't need a regulator.

3) The rectangle electric pump: This is your "Lift Pump". It only operates while cranking the engine. If you can think of an old outboard engine... there was always a "Fuel Bulb" in the system. And... before starting it for the day... you would reach in the back, and physically pump the bulb to make sure there was fuel in the line. (The fuel would drain back to the tank overnight) In our boats... the same thing happens. But, they replaced the bulb with the electric pump. SO... while at cranking speed... the diaphragm pump is VERY inefficient, and you would have to crank FOREVER if the filter was dry. So, they installed the electric pump to quickly suck fuel from the tank, and into the system. FYI... the 175 Sportjet didn't have this pump... and it was a bastard to start cold.

 

[Dr Honda]

Couldn't have said it better. LOL



Since we know it runs with fuel in the vapor tank... we need to figure out why it's not coming up from the tank.

I would check the other 2 pumps... AND... make sure the filters are OK. There is a big spin on filter that you can see... but there is also a small filter on the electric lift pump. If you look at it... the long fitting on the bottom of it, is actually a filter. It's small, and STUPID !!!! (Way too small for this engine) I would replace it with a regular barb fitting, and a large in-line filter.

The other thing could be that you have a small hole in the feed hose. If there's an air leak... it can't suck fuel up. So... check the hose from the tank to the engine. (including the fuel pick up in the tank)