Engine Shutting down

[gibsontd]

I spent more time than usual motoring the last two weekends on my Ericson 27, and have experienced engine shutdown twice after running for 2-3 hours. The engine temp never goes above 140, but seems heat related. I have electronic ignition and electrical fuel pump. Could one of those be suffering from heat related issue, or should I be looking for another cause?

[Don Moyer]

In answering any question relative to intermittent shutdowns which starts out with the phrase: "Is it possible that----------", the answer always has to be yes, until we know what the real cause of the problem turns out to be. The real challenge is in ferreting out which of the potential causes have the highest likelihood of being the real cause. Below is a technical note on the subject which may assist you in getting started:

TROUBLESHOOTING INTERMITTENT SHUTDOWNS

IMPORTANT NOTE: During most troubleshooting work, it's frequently necessary to turn the engine over on the starter with the engine NOT STARTING. Be sure to close the raw water thru-hull valve during these times, so as to avoid filling the exhaust system with raw water until it backs up into the exhaust manifold, and into the combustion chambers of the engine.

In troubleshooting intermittent failures, it's critically important to focus on the exact nature of the shutdown. For example, running out of fuel usually results in a rather "soft and gentle" shutdown. Small missing sensations may be noticed that gradually get worse until the engine finally stops.

On the other hand, failures within the primary ignition system (similar to what would happen if someone inadvertently turned the ignition switch off), the shutdown would be very sudden - perhaps even "startling".

Familiar causes of fuel starvation include dirt in the carburetor, clogged fuel tank vent line, faulty fuel pump (or electrical connections in the case of electric pumps), clogged filters, etc.

If the shutdown drags on long enough, you can try pulling the choke about half way on before the engine quits completely. If you can affect the engine performance (even a little bit) with the choke, it is good confirmation that you're dealing with some sort of fuel starvation.

If the shutdown feels as thought some one inadvertently turned off the ignition switch, the likely cause of the shut down is an open circuit somewhere in the primary ignition system - frequently in the boat's circuitry.

To confirm an ignition failure, remove the coil lead from the center terminal of the distributor cap AS SOON AS POSSIBLE AFTER A SHUTDOWN, and hold the end of the lead close to the block or head (about 3/8" away). Check for spark between the coil lead and head as you turn the engine over on the starter.

The reason for moving quickly in the preceding step is that many faulty connections within the primary ignition system will work after they cool - sometimes within a few seconds. Therefore, even if you do see a spark in the preceding step, don't completely abandon your first assessment that the problem may be in the ignition system.

In pinning down a loose connection in the primary ignition system, it is frequently necessary to install a "diagnostic" jumper wire between the coil (positive terminal) and the positive battery cable at the starter solenoid. If the intermittent shutdowns cease, you've confirmed that the problem is somewhere in the boat's ignition system.

NOTE: It has been very useful in several troubleshooting episodes in the past to also run the jumper wire directly to the electric fuel pump (where one is installed), to rule out a failure of the oil safety switch. If the engine runs OK with this jumper wire run to both the coil and the fuel pump, you can isolate the exact problem by removing the wires one at a time.

Another distinguishing feature of a shutdown could be that it is neither soft nor sudden, but that it hesitates (stopping and starting) sharply in an almost aggravating way. The engine may even backfire or "pop" a bit in this mode. Such an indication could mean that the coil is breaking down when it gets hot, or that the condenser may have worked lose on its mount, or that there's a very loose connection somewhere in the primary ignition circuit (possibly an intermittent short to ground).

Finally, have you performed any maintenance on the engine recently? Whenever you experience problems after performing maintenance, always go back over every step of your work to see if you overlooked something. This is one of the most fertile places to find reasons for intermittent shutdowns.

Good luck,

Don

[gibsontd]

Thanks for the response! My shutdown problem fits into your "soft and gentle" shutdown discussion, so I will look into fuel related problems. Also, adjusting the choke did improve the performance slightly. The only maintanance item recently, is the addition of a fuel filter (purchased from your website). I have had some problems re-seating the connection at the carb, so I will check on getting a new fitting. Any recommnedations on where to get a new carb fitting, I didnt see one listed.

[Don Moyer]

The fittings on the carburetor are 1/8" pipe thread and should be available at most any local hardware or West Marine store.

Don