Motor dies and lacks its normal luster performance-wise

[Ran-Dee9229]

I have a new problem - engine mysteriously dies (3 times in A 30 minute trip). We are thinking water in the fuel. Mechanic says everything checks out well otherwise. Not sure how to deal with this. I did had the tank scrubbed a couple times with in the last 5 years. Last time was 18 months ago when I also had an additional high end fuel filter installed that is supposed to catch the water. Have not filled the fuel tank since May 2019 but only have only about 8 hours on her since then. Cannot recall if I put the fuel additive in it before leaving her sit (after 3 hours of use) for 9 months.

Also she seems to be starved of fuel. Fuel pump ticks nicely at start and the lift pump (?) seems right. The tach seems to be suddenly off too after we just replaced a faulty ignition wire -coincidence? Tack shows 2800 RPM but motor seems to be churning closer to 1800 RPM and this flat out - top throttle.

I probably have about a 1/2 tank (~10 gallons remaining in the tank). I need to check the level.

 

[dlochner]

Fuel Starvation and The Obscure Ball Check Valve

On September 20, 2019, I was motoring back from a few enjoyable nights at my favorite local anchorage when I experienced a fuel starvation issue for the first time in my boat. We have sailed Aquavite since 1998. The engine simply sputtered and died, would restart after a few minutes and die...

forums.sailboatowners.com

 

[Davidasailor26]

+1 for the filter check valve like Dave posted. Also - check the filter bowl itself to see if it’s collecting any water. If not of those check out whether the fuel tank vent could be plugged. If the engine starts to bog, or just after it dies, open the fuel fill and listen for an inrush of air.

For the tach - Try an optical tachometer to see what it’s really turning. Full out should be closer to 2800 than 1800, so if you’re really only getting 1800 then maybe the fuel problems are more consistent than just stalling every 30 minutes.

 

[higgs]

What kind of engine?

 

[Benny17441]

90% of engine problems are fuel related. Condensation can put a significant amount of water in the fuel which coupled with bacteria growth can develop into globs that can block the fuel pick up tube. You have said the tanks was scrubbed 18 months ago so I will move on to other possible causes. When you talk about a high end filter are you talking about the Primary/water separator? How many microns? The engine mounted Yanmar secondary is a 2 micron filter, the recommended primary filter is a 30 micron as a lower micron filter will be more prone to clogging. While the engine is running, is it running well? If the fuel is good, it should. If there is water in the fuel it should show up in the water separator; make sure the filter is not clogged. Is the engine starting well after being laid up for 24 hours? If it is an air leak in the lines should not be the cause although a very small air leak over a long period of time could get some air trapped in the lines can affect the adhesion in fuel. Go ahead and bleed the fuel system as some are a little stubborn to release trapped air. With the engine off follow the fuel lines from the tank down to the secondary filter, fuel pumps and see if you find any fuel leaks. Where fuel leaks out when the engine is running air can leak in when the engine is off. Lines connectors and bleeding screws are the primary suspects. Is your fuel pump mechanical or electrical? A failing electrical pump may intermittently fail to deliver fuel. A failing mechanical pump usually shows a fuel leak and a gradual decline in pumping capacity. If everything checks out, you have to go back to tank for a possible clog. You could install an outboard tank with fresh diesel fuel and connect it to the fuel line and if the engine runs flawlessly then you could confirm the problem is in the tank. I would first recommend having the fuel polished. It is a process much like " kidney dialysis" where the fuel is pumped out of the tank and passed through a series of filters before being returned to the tank. I have seen the powerful pumps of these polishing machines suck out globs in the fuel of some tanks. This process will not entirely clean the bottom of the tank like a scrub but usually resolves pesky fuel issues due to water and clogging. good luck.

 

[31seahorse]

Sludge (or some other foreign substance) intermittently blocking the tiny screen at the lower end of the pick-up tube in the tank. The fuel polishing you mentioned is a good idea, but check for the screen at the lower end of the tube too.

 

[odaydokay]

Check the fuel pump connections. The ground wire on mine came loose and i got intermittent fuel delivery before it quite altogether. I am assuming you have an inboard when I say this, but more info from you would help us all.

 

[Timm R Oday25]

Something that hasn't been brought up is a plugged vent . I'm guessing that with an Oday 25 you have either a inboard diesel or a saildrive . I've yet to see an Oday 25 with a saildrive ,although I'm sure it's possible . Your symptoms sounds exactly like your vent line is at least partially plugged . After the engine shuts off as it can't overcome the vacuum ,gradually the air pressure equalizes and you are able to run the engine for a short time . It costs you nothing but a few minutes to check this out . I hope this helps

 

[MitchM]

start w engine cold. take a clean white rag and wipe the fuel lines slowly looking for any sign of pink diesel , that would ID a leak. if there's nothing on wiping the fuel delivery system with engine off, start yr engine and CAREFULLY do the same test when your fuel starvation/ rough running starts. maybe you have an air leak, and with the air leaking you may get pink diesel on your test rag. (cheap old mechanic trick. )

 

[Ken13559]

Sludge and gunks do get stuck inside the Racor filter head and not just in the filter element.
Do check that portion. Leave nothing "un-turn". Sludge and gunks goes everywhere along the line from tank to Injectors. Our eyes and thoughts often skips some small or "insignificant" components.

Ken Y

 

[Ran-Dee9229]

90% of engine problems are fuel related. Condensation can put a significant amount of water in the fuel which coupled with bacteria growth can develop into globs that can block the fuel pick up tube. You have said the tanks was scrubbed 18 months ago so I will move on to other possible causes. When you talk about a high end filter are you talking about the Primary/water separator? How many microns? The engine mounted Yanmar secondary is a 2 micron filter, the recommended primary filter is a 30 micron as a lower micron filter will be more prone to clogging. While the engine is running, is it running well? If the fuel is good, it should. If there is water in the fuel it should show up in the water separator; make sure the filter is not clogged. Is the engine starting well after being laid up for 24 hours? If it is an air leak in the lines should not be the cause although a very small air leak over a long period of time could get some air trapped in the lines can affect the adhesion in fuel. Go ahead and bleed the fuel system as some are a little stubborn to release trapped air. With the engine off follow the fuel lines from the tank down to the secondary filter, fuel pumps and see if you find any fuel leaks. Where fuel leaks out when the engine is running air can leak in when the engine is off. Lines connectors and bleeding screws are the primary suspects. Is your fuel pump mechanical or electrical? A failing electrical pump may intermittently fail to deliver fuel. A failing mechanical pump usually shows a fuel leak and a gradual decline in pumping capacity. If everything checks out, you have to go back to tank for a possible clog. You could install an outboard tank with fresh diesel fuel and connect it to the fuel line and if the engine runs flawlessly then you could confirm the problem is in the tank. I would first recommend having the fuel polished. It is a process much like " kidney dialysis" where the fuel is pumped out of the tank and passed through a series of filters before being returned to the tank. I have seen the powerful pumps of these polishing machines suck out globs in the fuel of some tanks. This process will not entirely clean the bottom of the tank like a scrub but usually resolves pesky fuel issues due to water and clogging. good luck.

Thanks. Actually I may have had my tank polished and not scrubbed. Am not certain. She ran without dying yesterday for about an hour as I motored out, sailed and motored back. Seemed like full power was not quite what it used to be but was better than the last time I used her.

Checked for leaks and thatlooks okay. electric fuel pump ticks away as it should. My tank is very low now,thinking maybe I should siphon it out and discard the fuel At a recycling place and put fresh fuel in. As for the filter, we just cleaned and changed all filters where appropriate. I’ll post a photo of it, maybe you’ll know which model it is.

 

[Ran-Dee9229]

Something that hasn't been brought up is a plugged vent . I'm guessing that with an Oday 25 you have either a inboard diesel or a saildrive . I've yet to see an Oday 25 with a saildrive ,although I'm sure it's possible . Your symptoms sounds exactly like your vent line is at least partially plugged . After the engine shuts off as it can't overcome the vacuum ,gradually the air pressure equalizes and you are able to run the engine for a short time . It costs you nothing but a few minutes to check this out . I hope this helps

I have an ODay 29 with an M-12 Universal diesel inboard. Not sure where is the vent line?

 

[Davidasailor26]

If you’re able to view the top of the tank you’ll likely see 4 fittings - engine supply and return (both routed toward the engine), a larger fill hose, and a vent hose. Trace the vent hose from there and you should see it coming out on the hull, possibly near where the deck fill fitting is.