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Old 07-31-2012, 02:35 AM
Jon K Jon K is offline
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Request advice with stalling engine

Thanks in advance for your advice.

My 1985 Atomic 4 has developed some problems, it stalls after reaching 180 degrees and won't restart until it cools. It also has a history of performing fine under power, then stalling when brought to idle when returning to port.

History:

I bought a late 1970s Ranger 28 in 2006, the marine surveyor said it was sound and we began sailing the boat and updating the cabin.

Recently I have noticed that the wiring in this negative-ground system uses different colors of wire, spliced partway through each run to another color. With red, orange, white and yellow wires, the only color absent on the ground side is black. I've added a second cigarette lighter receptacle so the GPS and handheld spotlight can be run at the same time, not much else.

I read about the Atomic 4 and learned how to do a few things, including how to change the oil. It is a traditional, un-upgraded engine with a new heat exchanger - freshwater cooling and two pumps. It burns a little oil, perhaps a quarter-litre per season of 10-12 hours of use. I tend to run the engine near or at top RPM, using my ear to avoid over-throttling. After 5 seasons I have put about 70 hours on the engine.

At one point the engine was overheating, it turns out that the saltwater through-hull was clogged with seaweed. A coathanger was an easy tool to clear the clog. Now it runs at 180 degrees all the time.

Every season we make a long trip that begins with a 5-hour crossing of the Georgia Straight between the mainland and the Gulf Islands, here in the Vancouver, BC area.

In the fourth year, returning from one such trip, the engine stalled after a few hours, when brought to idle from 2-3 hours at full speed. We had slowed to make a passage between two islands, possible only at flat water. Luckily a passing motorboat offered us a tow through, and we decided to make port nearby to diagnose the problem. As it turned out, during the passage the problem had cleared and we were able to restart and continue home.

After a speedy 3.5 hour crossing under sail and 2/3 power, I idled the engine to drop sails and moor the boat. Engine died and would not restart. We took a tow in and ended the season.

Last year in Spring I took the boat for service, only to stall half-way after running for about an hour. A friend brought some methyl hydrate which we added to the fuel, and we blew through the line to attempt to clear any blockage - the ragged running of the engine suggested a fuel starvation problem.

After 30 minutes or so the engine restarted, and so I handed the boat over the boat yard manager who convinced me to install new fuel lines, a Rakor filter, and an electric fuel pump to pull the gas through it. Electronic ignition was added, as well as new plugs and wires.

After the service the engine seemed to run well, however issues soon developed:

1. The electric fuel pump wasn't working -- I rewired it myself by adding a new hot lead from the engine cutoff switch. Now it spurts gas at the carb whenever I test it.

2. The common ground for some house wiring is gone; I rewired the house water pump with a ground directly to the gear housing. The mast light stays on whenever the batteries are engaged.

I think the mechanic was a little clumsy, or changed the wiring while installing the fuel pump. These are not critical issues for me, I will rewire at some future time. Just more data points.

This season I have completed a recent journey with the following symptoms:

3. Fairly constant loss of coolant, needing 1/2 litre for 30 minutes engine time. First noted when engine overheated with steam in the exhaust. I thought at first it was oil burning, but the cloud was white and smelled like antifreeze not stinky like oil.

4. During the same hot-engine breakdown I pulled plugs 1 and 2. Both looked okay, but I saw no fuel in the cylinders while cranking. Maybe it just evaporates in the hot engine. No obvious issues in the cylinder or plugs.

5. At the same time I tested for spark -- good spark. Tested for fuel at the carb -- lots of gas.

The engine restarted after ccooling, but once again stalled and would not restart when we slowed down to begin mooring.

So I tested a few things:

6. Thermostat works fine in boiling water.

7. Oil at Low mark, I topped it up, lubricant was a little dark but no obvious water.

8. Engine always starts easily and runs fine at idle, or while cool.

It's dificult to access the carb, although the fuel pump and filters are available. The other side of the engine is somewhat accessible, and the head area is exposed under the companionway stairs.

I am tempted to remove the head but I'm experienced mechanically just enough to know that this may introduce more issues, and right now the engine runs, enough at least for local sailing.

I hope the forum can offer me suggestions to diagnose the problem. I am motivated, have tools, shore power, flashlights, and a multimeter. I can rent or borrow a compression tester and know what it is for.

Where do I go from here?

- Jon
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