DF50 - Runs when high rpm lever is up, dies when putting into gear.

[tegwilym]

Looking for advice on what to try. I have a DF50 motor on our Macgregor and having issues keeping it running. It's a "new" to us boat, and keep finding new issues with it even before we get it in the water.

The details (everything done so far - even unrelated):

• Replaced and gapped spark plugs
• Replaced the plastic low pressure fuel filter
• Replaced both male and female fuel connector to motor/tank
• Added a Y valve to select left or right tanks.
• Brand new tanks, fuel hoses and primer bulbs.
• Replaced impeller.
• I just have a few gallons in the tank (fresh supreme fuel with a splash of Sea Foam)

Details of motor:

• DF50 Suzuki 2005
• Macgregor 26M motorsailer
• Possibly sat unused for at least 3 years.

Symptoms:

• I got it running, but only when I have the high-idle lever in the up position.
• It will run fairly smoothy in this condition. Will go as low as about 800-ish RPM and close to 3,000 Rpm (it starts to stutter around there, but I was told there is an RPM limiter at 3,000 so that's probably normal)
• When I lower the high-RPM lever, to put the prop in gear, it just quits before it's in gear.

What could this be? (my ideas)

• Idle speed on engine too low? Dies when the lever is down.
• Fuel issue? It twill run, but could it be the other filter (the high pressure filter on top of engine)?
• Leaking hoses? They are old, but I have them connected securely, but of course there is the chance of an air leak maybe.
• One of the fuel pumps?

I'm not a hard-core mechanic by any means, and we did check around the local marine shops and none of them work on Suzuki engines. *ugh!*

Any ideas are appreciated!

Thanks,

Tom
Sturgeon Bay, WI