Fuel pump question ...

[JOHN COOKSON]

IMO every possible cause is on the table until that part of the fuel system (tank, filters, fuel pump, carburetor) is shown not to be the cause of the shut downs.

Back to the tank for a moment: This is a bit far out but here goes anyway:
The engine starts and runs normal at low RPMs. As RPMs increase more fuel is needed which increases the suction at the end of the pick up tube in the tank, which pulls crud at the bottom of the tank up against the bottom of the pick up tube blocking it and the engine dies. After the engine dies there is no longer any suction at the end of the pick up tube and the crud drops off. The cycle is repeated.

TRUE GRIT

Edit: Is there a solenoid at the top of the tank pick up tube that might be acting weird?

[Antibes]

Have you checked all the fuel connections. If they are loose or too tight on the hoses, air can get in and cause stall out.

[Robs Hubris]

IMO every possible cause is on the table until that part of the fuel system (tank, filters, fuel pump, carburetor) is shown not to be the cause of the shut downs.

Back to the tank for a moment: This is a bit far out but here goes anyway:
The engine starts and runs normal at low RPMs. As RPMs increase more fuel is needed which increases the suction at the end of the pick up tube in the tank, which pulls crud at the bottom of the tank up against the bottom of the pick up tube blocking it and the engine dies. After the engine dies there is no longer any suction at the end of the pick up tube and the crud drops off. The cycle is repeated.

TRUE GRIT

Edit: Is there a solenoid at the top of the tank pick up tube that might be acting weird?

Hmmmm ... so, perhaps if the recently filled batch of fuel was bad/crud laden ... anything is indeed possible at this point. I don't know about the selenoid. I'll take a look though.

[Robs Hubris]

Have you checked all the fuel connections. If they are loose or too tight on the hoses, air can get in and cause stall out.

I did cursory checks over the lines after trying the start routine a few times ... I didn't detect any hint of leaks. Which doesn't mean it's not possible ... but I'm pretty sure I would notice the smell of the gas, even in small quantities. I've never smelled a hint of gas leak or strong fumes in Hubris so they should stand out. Not off the table as a possible issue though ...

[Antibes]

I had no fuel leaking out when air getting in caused shutdowns

[ndutton]

Please review John’s post #22, auxiliary tank.

[Robs Hubris]

Please review John’s post #22, auxiliary tank.

And Jerry's #27 post on same ... yes indeed, I got it. Hope to put it into action tomorrow ... stupid work gets in the way of boating far too often!

thanks Neil.

[Robs Hubris]

I had no fuel leaking out when air getting in caused shutdowns

thank you. Can you describe the shut down pattern your experienced?

[Antibes]

I was doing my end of the year run, 21 miles and the engine sputtered to a stop and would not restart until I got a tow in. It ran fine for a long time before dying out

[Robs Hubris]

Update ... bad news

A twist to the story ... prepared to run a separate gas tank line, ran the engine, died as before, but I noticed something funny about the sound of the engine. Checked the oil ... no oil at all. As I had just changed and refilled the oil this spring (and it rarely uses much through a whole season) I figured this was not good. Added oil, still had the problem, but I noticed oil in the exhaust.

Talked to a mechanic I found that works on Atomic 4's and he said he's "90% sure" that its the rings, meaning we'll have to pull the engine at a nearby marina (and I'll have to find a tow over there) and have it rebuilt.

Beyond the cost, there goes much of my sailing season ... argh.

thanks again for the advice and help. I feel pretty stupid for not spotting this sooner, but, live and learn.

best,
rob

[Dave Neptune]

That's an awful lot of oil to get past the rings!!!! Did a compression check get done?
The oil level will not cause the engine to run rough or die unless it is seizing or the crankcase is full of oil.

Just how much oil do you see in the exhaust? And can you supply a picture of the plugs.

I would think that for that much oil to "go away" that it is getting to the exhaust via another route and about the only way that will happen is something is cracked. Have you had a recent overheat or a freeze with water still in the block.

That much oil burning 9ff would leave one heck of a "Batman smoke screen" be hind you.

Dave Neptune

[ndutton]

Rob, whenever you get this repaired or replaced I recommend the Early Warning and Diagnostic System (EWDS) from Moyer Marine. It monitors oil pressure and fuel pressure plus three other parameters on the fly and alerts you audibly and visually if any are out of range as well as which are out of range. It will really help in future troubleshooting.

[Robs Hubris]

That's an awful lot of oil to get past the rings!!!! Did a compression check get done?
The oil level will not cause the engine to run rough or die unless it is seizing or the crankcase is full of oil.

Just how much oil do you see in the exhaust? And can you supply a picture of the plugs.

I would think that for that much oil to "go away" that it is getting to the exhaust via another route and about the only way that will happen is something is cracked. Have you had a recent overheat or a freeze with water still in the block.

That much oil burning 9ff would leave one heck of a "Batman smoke screen" be hind you.

Dave Neptune

Those are really good points... No I never saw that amount, or any, oil smoke coming out of the back... There is a very slow leak in the water exhaust system... Could that do it?

[roadnsky]

There is a very slow leak in the water exhaust system... Could that do it?

NO.
Something isn't right here.
Can you do a compression test?

If you don't know how to do it, let us know.
It's an easy procedure that will tell us a lot.

[thatch]

Loosing the oil rapidly and having it show up in the exhaust is very odd. It suggests a breach between the pressurized oil gallery (high pressure) and a water jacket (low pressure). A block pressure test should verify or eliminate this theory. I wonder if Don has ever run across this situation?
Tom