Engine quitting when it reaches 160

[Orion C&C 33]

Hello all...

I have taken ownership of a C7C 33 with an Atomic 4... this past week. The previous owner made no mention of my following condition.

Here's my issue, when underway with the engine running 1400 RPM @ 3-4 Knots the engine runs fine and smooth. However, if I try to increase speed to 5 knots the engine temperature reaches 160 on the gauge and the engine begins to falter and quit.

I waited 15-20 mins for the engine to cool down and she re-starts... This happened 4 times same thing every time, as I took her home to her new port.

As I drifted I googled this symptom... and came up with improperly gapped plugs. I called the owner and he said that he just installed them straight out of the box and did not gap them.

Since I don't own a spark plug gap tool to measure for .035 (on my way to buy one now) for the proper gap.. I am hoping that some of you might confirm that this is the issue with my engine.

I am planning to remove them check the gap and reset it the the proper distance... and run the engine to the stalling temp of 160 at the dock and see what happens.


I would appreciate any feed back...

Cheers

Mel

[Ram41662]

Since it appears to happen when things warm up, you might consider the coil could be getting weak. If weak, when it warms up it will produce a weaker spark until it fails.

Try the plugs first. If that fixes it, great! IF not, check the coil.

[JOHN COOKSON]

During the shut down time pull the wire out of the center terminal of the distributor and hold it near the engine while cranking the engine. If you don't see a blue white ~1/2 inch spark then the coil is suspect.

TRUE GRIT

[roadnsky]

...when underway with the engine running 1400 RPM @ 3-4 Knots the engine runs fine and smooth. However, if I try to increase speed to 5 knots the engine temperature reaches 160 on the gauge and the engine begins to falter and quit.

I waited 15-20 mins for the engine to cool down and she re-starts... This happened 4 times same thing every time, as I took her home to her new port.

Mel-
First, welcome to the Forum!

A few questions...
The 4 times it happened:
did it always run ok at lower RPM until you reached above 1400?

And to be clear:
it stumbles and then dies rather than shuts down suddenly (like turning off the ignition) right?

Do you know how old your exhaust system is?

[tenders]

Also: how does it run if you throttle up to a high RPM with a cold engine?

If it’s temperature-related, coil would be more suspect. If it’s RPM-related, an exhaust blockage (or bad timing or worn cap/rotor or old condenser or sticking advance weights) might be more likely implicated. I would not tend to blame the plug gap for this symptom - the A4 is not all that sensitive to gap width.

[ndutton]

In a pinch you can use a dime as a gap gauge. It's a little much @ 0.050 but I've heard of A-4's running fine @ 0.045"

[Orion C&C 33]

Thank you everyone... for the suggestions

I found out my problem on the motor.
I feel so incredulously stupid.... for not checking back in on this forum, I've been tinkering on the engine since I posted.

Please accept my apologies for my delay in response.

This is what I discovered spark plugs #1 and #3 were not tightened and seated properly, you can literally turn them out by hand.

and #2 and #4 were a little snugger but not by much... I assumed when the previous owner had changed out the plugs he would tighten them!!! But obviously not the case.

After checking out if they were gapped properly I torgued them down to the proper ft/lbs as suggest in the Atomic service manual...

Started it up and she ran like a Beauty right up to 160 degrees without stalling... then I tested the motor further and put it in gear while still tied to the dock and ran the engine to 180 degrees and again no stalling... ran it under load for 30 mins and nothing.

But in the process I and along with a friend have discovered that the electric fuel pump is kaput!!! It has to crank forever to get it to start... tested that issue out after cranking for about 5 minutes pulled the #1 plug out and she was visibly dry.

With some starter fluid squirted in the #1 pisten and she fired up immediately so I guess replacing the current electric fuel pump is next on the list, while she's on the hard.

Thank you for the warm welcome and for the help... I really much appreciate it.

Cheers

Mel

[Orion C&C 33]

Mel-
First, welcome to the Forum!

A few questions...
The 4 times it happened:
did it always run ok at lower RPM until you reached above 1400?

And to be clear:
it stumbles and then dies rather than shuts down suddenly (like turning off the ignition) right?

Do you know how old your exhaust system is?

Hi Jerry...

I could run it to 2000 rpm and still ran smooth... it was when the engine temp reached 160 then it sputtered and died like it was struggling... I have discovered that all my spark plugs were loose. Like turn them out by hand loose.

I feel so incredulously stupid for trusting the previous owners work... I know better next time to always perform a double check before leaving the dock... especially since I had my family on board.

Mel

[ndutton]

Mel, do you run the fuel out of the carburetor when you shut down or simply turn off the key?

[Orion C&C 33]

I just turn off the key... How do you run the fuel out of the carburetor ??

This is new to me....

[ndutton]

I just turn off the key... How do you run the fuel out of the carburetor ??

This is new to me....

. . . . by closing a fuel valve and letting the engine run until it starves itself of fuel but that's not my point. Thus far you've said nothing that condemns the fuel pump so maybe not so fast on replacing it. Of course you can if you want, just that your reports do not fit a non functioning pump.

Examples:

It has to crank forever to get it to start You do not need a functioning fuel pump to start the engine. It has ample fuel remaining in the carburetor bowl to start and run for a minute or more without any fuel pump operation. My question about shut down procedure confirms there's fuel in the bowl.

ran it under load for 30 mins and nothing Not likely with a non functioning fuel pump. It's a remote possibility with a fuel tank situated so a strong siphon exists but I wouldn't count on it.

Your starting fluid test and dry #1 plug both confirm a fuel problem but let's not jump to conclusions it's the pump. It's possible it is, just that nothing's conclusive yet. Your symptoms may be due to other causes, even a combination of causes. Hard starting may be caused by a poorly functioning choke not closing all the way. A non-functioning fuel pump may be due to a failed oil pressure safety switch (OPSS). I encourage you to explore the entire fuel system before replacing things, home in on the real problem first. A fuel pressure gauge immediately ahead of the carburetor would answer a lot of questions about now.

[Orion C&C 33]

. . . . by closing a fuel valve and letting the engine run until it starves itself of fuel but that's not my point. Thus far you've said nothing that condemns the fuel pump so maybe not so fast on replacing it. Of course you can if you want, just that your reports do not fit a non functioning pump.

Examples:

It has to crank forever to get it to start You do not need a functioning fuel pump to start the engine. It has ample fuel remaining in the carburetor bowl to start and run for a minute or more without any fuel pump operation. My question about shut down procedure confirms there's fuel in the bowl.

ran it under load for 30 mins and nothing Not likely with a non functioning fuel pump. It's a remote possibility with a fuel tank situated so a strong siphon exists but I wouldn't count on it.

Your starting fluid test and dry #1 plug both confirm a fuel problem but let's not jump to conclusions it's the pump. It's possible it is, just that nothing's conclusive yet. Your symptoms may be due to other causes, even a combination of causes. Hard starting may be caused by a poorly functioning choke not closing all the way. A non-functioning fuel pump may be due to a failed oil pressure safety switch (OPSS). I encourage you to explore the entire fuel system before replacing things, home in on the real problem first. A fuel pressure gauge immediately ahead of the carburetor would answer a lot of questions about now.

Hi Neil..

Very good suggestions... I am new to all this, not very mechanical minded, but I do like to solve problems and I'm not afraid to get dirty and learn from all you good folks on this forum.

Let me ponder on you advice... just as you advise in regards to the fuel pressure gauge, I don't have one at the moment.

So, If I'm going to change things out might as well replace everything and add on the gauge.

I do like the peace of mind... and not a big fan of being dead in the water other than my sails to move.

I'm fortunate enough to have a partner who says "change it all if necessary"

I'll get back to you after source out a fuel gauge... that can read the low PSI...


Cheers

Mel

[ndutton]

Do you have the MMI manual?

[Orion C&C 33]

Hi Neil

Yes I do printed it off one copy for the boat and one for bedside reading... I have a lot to catch up on the Atomic 4.

[Ram41662]

Hi Neil

Yes I do printed it off one copy for the boat and one for bedside reading... I have a lot to catch up on the Atomic 4.

I know this might be a silly question, but is your manual the Moyer Marine, Inc. manual or is it a version of an OEM manual? I have several versions of the OEM manual , all were available in PDF format, as well as a copy of the MMI manual, which is only offered in print.

That said, I will admit to scanning my copy to a PDF file I keep on a dedicated tablet that works as my "universal device manual library",