911....stb engine shutdown oil pressure

I'm on the hook, alarm came on stb engine. Shut down immediately.
Oil level good. I changed the pressure gauge a couple of weeks ago. Engine will start but shuts down. Would that be pressure sender or oil temp that would do that?

I have another new pressure sender on board.engine has been stumbling around 2500 the past few days. Changed filter after really rough ride but think this was really the issue.no noises... Would be shocked if it's really a pressure problem but being careful


Don't want to dock on one! Should I try other new sender?

THis is an electronic engine?

No...1988 mechanical fuel pump carb. Prestolite ignition..no points.

bobct said:

Engine will start but shuts down. Would that be pressure sender or oil temp that would do that?

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There should be no means for the engine to turn itself off. Do the oil pressure and water temp gauges appear normal at startup? It it doesn't start, does the oil pressure come up on the gauge?

Concur on the "no auto shutdown" mechanism on that one.

I'd suspect fuel delivery issue or ignition...check for spark; if present move to the fuel system.

Ha! funny thing; I just returned from a dive 30 minutes ago. My port engine started buzzing. Defective oil pressure switch... The starboard one did this 3 years ago.

false alarm - literally

weird sequence of events but long story short, the engine stalled. The buzzer went off and my wife said the oil pressure dropped to zero which is why I went on that tangent. The boat has never done that so I assumed it shut down by design. I replaced the same engine oil pressure sending unit a few weeks ago, thought maybe it went bad, etc.

I started troubleshooting but had an "ah hah" moment in the process...this problem actually started last week. We came back through 5-6 footers for about two hours. About an hour into the ride, the same engine was cutting out around 2,500. I figured all the action had stirred up the tank so I backed off and made it home. I changed the canister filter yesterday and it was pretty dirty. Left this morning and it did the same thing and THEN 30 mins later it died.

I changed the carb filter and removed the canister filter again. I noticed there was hardly any gas in the canister unlike yesterday when it was full (and it was clean). I sprayed some starting fluid into the flame arrestor and it ran for a second. Now I knew it was fuel related.

Switched over to my Port tank and it fired right up. That's how I got home both engines running fine.

Doesn't this sound like a clogged or bad anti-siphon valve? I've read about these causing this exact issue but don't know where it is on my boat. I removed the vent line and unscrewed the fitting out of the tank but it was just a straight connection and it was clear.

Is it under the copper fuel line going into the top of the tank? Mark, I just asked about this last week and you suggested removing the deck fill plug and crank the engine as a test. I did that but it didn't start. This was before I noticed the lack of fuel in the canister and maybe didn't let it crank long enough.

Gas gauge reads normal and was the same as the other side at around 1/2 tank.

Back to the anti-siphon. The only other fittings I see on top of the tank are the fill, sending unit, copper supply and another fitting which looks like a blank plug.

Any ideas?

Bob

Did you grease the new seal on the new canister filter and throw the old one away?

Could be junk collecting on the screen in the pickup tube or hanging up anti-syphon valve...or an air leak as DD suggests with the Q above. Either way, glad it was just a false alarm. Would also be a golden opportunity to get the wife dialed in on how the alarms work. Stall then buzzer is expected; Buzzer then stall is BAD.

cracking the fill plug will equalize the tank's pressure if the vent is clogged; if that makes no difference, I'd concentrate on the supply lines.

Since you get dirty filters with only a few hours, I'd suspect lots of crud in the tank....As FastJeff would say, "welcome to evilnol!"

You can plumb up a small vacuum gauge on the 'spare' outlet fitting on thee spin on if you want a positive indicator of it clogging up.

I didn't re grease the seal since I just changed it yesterday but I ran back on this filter no problem. The only thing that changed to get me running was the tank so I'm assuming everything after the crossover valve is not a suspect on the Stb side.

The filters have actually stayed pretty clean all year, I checked but didn't change the filter in question about 3 weeks ago. That was after about 60 hours of running and it looked fine. Big difference in three weeks after my rough ride.

I'll try and run it tomorrow with the fill plug open (now that the engine is primed) and see if that makes a difference. Will the pick up tube be under the copper supply line?

Re: false alarm - literally

bobct said:

I changed the carb filter and removed the canister filter again. I noticed there was hardly any gas in the canister unlike yesterday when it was full (and it was clean).

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WHen you get air in the filter, usually that means the tank went dry or there is some leak in the fuel line connections, filter seal or crossover valve packing. Temporary use of a clear hose near the engine is sometimes used to check for air.

Bob,

Attached is a pic of where the antiiphon valve is on my 1990 Silverton with 454 Crusaders. Not all boats have these but should if the fuel line drops below the highest point of gas level in the tank anywhere between the tank and the engine...and I assume that is the case on most boats. I had a similar stalling problem a few years ago and after removing and cleaning the valve the problem never returned.

Erich

erich, thanks that looks just like mine. I just removed it and it "looks" clean so doesn't seem like a suspect at least visually. Was yours obviously clogged?

Going back to the boat now and will look into the tank with a borescope and also blow compressed air thru the vent line.

Update: Used my compressor to verify that vent line is clear. Then used borescope to make sure that supply and vent fittings were clear on the tank and both look good. I can see gas in the tank which if I didn't would be a bigger problem, 50 gallons that went somewhere else.

Bob,

It didn't look clogged but by pushing down on the spring loaded steel ball while spraying some choke cleaner into it, there was quite a bit of crud that came out.

Erich