Bad Fuel Pump?

[Airbear]

The Rotax 912 in my 2005 CTSW is acting up. It starts OK but runs rough especially at RPMs approaching idle. It will also stall at idle and will not restart. It seems to smooth out a little around 4000 RPM. There's never been a problem with the idle in the past. It's virtually impossible for it to restart once it stalls. It might cough and sputter a little but nothing resembling a normal restart. I also noticed a small fuel stain (12" x 6") on the ground under the blue tube from the fuel pump.

For reference, the engine has about 1250 hrs on it. It has approximately 250 hrs since the crankcase was replaced due to a fretting issue. We replaced the fuel pump at the same time. The ignition modules were replaced about then as well.

Would appreciate your thoughts.

[Roger Lee]

Maybe the pump, but take a look at another item or two. 12" x 6" is a big drain. I few drops is one thing, but not this. First sinking floats can cause these rpm symptoms so weigh the floats first, but they would have nothing to do with fuel out of your drain, but do some diagnostics first before throwing money at it. Weighing floats don't cost money and it helps rule things in or out. They have to be under 7 grams. Remove them, dry them off then weigh them as a pair. If these are okay then it may easily be your pump, but before I just threw money at the problem I'd do a carb sync and take a look. If the pump is that bad it may leak out the drain while running then if it did I'd replace it.

Food for thought,

The other thing is you have over 1200 hrs. on the carbs. Have they ever been overhauled? Not just inspected, but overhauled.

[Airbear]

Yes, the carbs have been overhauled a couple of times over the life of the engine. Most recent was about 100 hours ago.