Yanmar 75 HP turbo won’t stay lit

[EmeraldCoastSailor]

2007 engine in a Hylas 46 with 1500 hours. New filters in a dual racor setup, multiple tanks with good fuel, and it has run well for almost 100 hours in recent delivery. The left racor has bubbles rising from the bottom of the bowl. Is that a sign of air leak somewhere before or after racor? Not my boat and just trying to help a bud. It starts but won’t rev past idle and sometimes dies on its own.

[HeywoodJ]

If there are bubbles rising from the bottom of the bowl (is it clear?) I would suggest the leak is the Racor. If they are truly coming from the bottom then likely the drain is not properly sealed or there is a crack in the bowl (from over-tightening the drain ).

[bstreep]

What "Heywood" said.

[BillKny]

Bubbles == LEAK. No other answer.

[yachtgemini]

The Racor may have a blocked fuel line to the tank. It takes an awful lot of suction to make the Racor leak in normal circumstances and if your fuel flow is uninhibited you are not likely to develop that much suction.

The racor suction guage (optional) is usually a good indicator of such problems.

I would disconnect the incoming fuel line and either see if you can blow back down the line or attach a pump to check how good the flow is.

The first time I saw this problem was after starting a boat left idle for a year that had a bad dose of the 'jellied' fuel bug.

[Cadence]

If it's the Racors I'm thinking of it is what Heywood said. Might just be an O-ring or rubber washer at the bottom of the bowl.

[Scubaseas]

Originally Posted by yachtgemini

The Racor may have a blocked fuel line to the tank. It takes an awful lot of suction to make the Racor leak in normal circumstances and if your fuel flow is uninhibited you are not likely to develop that much suction.

The racor suction guage (optional) is usually a good indicator of such problems.

I would disconnect the incoming fuel line and either see if you can blow back down the line or attach a pump to check how good the flow is.

The first time I saw this problem was after starting a boat left idle for a year that had a bad dose of the 'jellied' fuel bug.

This exactly. While there are o rings in a Racor (both the body on some and the fittings) they usually won't allow air to be pulled in under normal running conditions. If the o ring is that bad there is usually a fuel leak. Likely there is a clog upstream of the filter in combination with an oring issue. Vacuum gauge on fuel inlet line would tell you for sure. Or just run a separate fuel supply like a jerry can with the pickup and return run into it and see if you stil have bubbles or running issues. I had one boat where the elbow of the tank pick up tube was clogged with sand and rust. Tank was clean, no algae, pick up tube/screen was clean but the fuel flow was severely restricted.

[EmeraldCoastSailor]

Took apart things so that we could by-pass the Racors and engine ran fine. Put things back together and engine ran fine. Something was preventing fuel from entering system but it cleared during our messing about. I failed to mention that gauge indicated pressure when we were having problems but after reassembly the gauge was reading near zero. It was in the racor connections but we are not sure specifically. I think my friend has a tank cleaning exercise in the future. Thanks for help via comments.