1998 1800 Regal 3.0l - won't stay running

[Jamesmk0]

I just finished a great year of boating in the Muskoka's. I was planning to pull my boat out of the water and complete my winterization routine, when my boat, which ran fine all summer would not stay running. The boat starts fine and runs for about 30 seconds before it stalls. Upon a immediate restart, it only runs for about 10 seconds before it stalls again. If I let it cool for an hour it will run again for 30 seconds before stalling. I replaced the gas filter that was attached to the bottom of the fuel pump (first time replacing in 3 years) and blew out the filter screen that resides in the gas intake on the carb (2bbl on a Mercruiser 3.0l engine); the fuel filter attached to the fuel pump was breaking down, while the filter screen in the gas inlet on the carb was relatively clean. If I hold the butterfly valve closed, the engine will continue to run and therefore believe the engine is likely being starved of fuel and the gas is likely OK (gas is approximately 2 months old). Although I understand these mechanical fuel pumps are relatively bulletproof, I pulled the gas line from the carb and turned over the engine and confirmed gas was being pumped through the lines.

My research suggests my next move would be to check/replace the siphon valve and clean the pickup screen that resides in the gas tank, however would appreciate any insights from those having similar problems. The other thought is the needle vale inside the carb may be plugged?

[jimq26]

You might check the Regal site for advice.

This is the Maxum site, and although our members usually know just about everything, I'm not so sure about Regal though.

[shrew]

Technically, it's a Mercruiser 3.0. The fact it's in a Regal is irrelevant.

[mmwjr]

Welcome aboard Jamesmk0

Yep 3.0 Merc same as used in small Maxums

By saying you are holding the butterfly closed I am assuming you are referring to the choke plate, correct?

This enriches the air to fuel ration as you stated which means the engine is lean.

To test the fuel pump you really need to verify its output pressure which should be ~ 6-7 psi.

A clogged fuel tank vent will also starve the engine although it normally takes about 15 - 30 minutes before this is noticed. Try removing the gas cap to see it the problem goes away if this is the issue.

At idle is the fuel spray nice and steady in the carb or sputtering?

Is the idle ruff? May be a vacuum leak at the carb base in with a carb gasket.

[Jamesmk0]

I will definitely try those. Given it fails so quickly, could the siphon vale cause this?

[mmwjr]

A clogged siphon valve may cause thus as well, it starves fuel to the engine.

Can you run the engine at higher rpms ok?