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Ok...What next...

J

jclays

Regular Contributor
Aside from my engine oil leak. Last weekend the wife and I were taking a cruise to lunch. Running at 2000rpm 14kt very nice. After 1/2 hr port engine starts to stall and miss as if out of gas. after restarting would would stall when I would advance the throttle. Could not get it to run more than a few seconds. Came home on one engine. Docked and went home. Last night (6 days later) hit the starter on the port engine, it fired up and ran with no issues. Rev ed the engine a few times. No issues. Clogged filter? Fuel pump going out? Maybe stuck floats or accelerator pump???
 
I'd suspect the fuel tank vent, if the engines were not sharing. Or, anti-siphon valve. When was the last tune up?
 
Problem did reoccur. Fired up both motors to back the boat in and properly dock her. The engine stalled out twice in the process. Each engine has separate tanks. Anti siphon valve?? What's that?
 
A device to prevent the contents of the tank being syphoned into the bilge if a line breaks/ leaks. It's usually located in a fitting right at the fuel tank. Not sure that's your problem--I vote for a flooding carb--but you might pull it out and clean it just to be sure.

Jeff
 
Where is this device located?? I have a 3/8 rubber marine fuel line from tank running 6ft to a fuel filter. Then a 3/8 rubber line from filter to fuel pump. Then 3/8 rubber line from fuel pump to carb. Im going to pull the carb and rebuild.
 
Use the tried and proven P of E... (process of elimination) and do this one item ONLY at a time.
With twin engines you have the advantage of being able to swap parts from one engine to the other.

Granted.... some parts just aren't worth swapping, and if questionable, it better serve us to simply replace them.
However, a carburetor is among one of these that is easy enough to change without much hassle.
A little time, new set of base gaskets, and there ya go.

If the issue follows the part that was changed, you've found the faulty part.

BTW, your anti-siphon valve will look like this one.
It will be installed directly into the 90* fitting that sits at the top of the fuel tank pick up tube.
Looks like a typical barbed fitting, but incorporates a mildly spring-loaded ball valve inside.

images

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or dirt accumulating on the screen at the bottom of the pickup tube...temporary use of an outboard fuel tank tank will tell you if it is tank related a lot quicker than swapping carbs.
 
Or.......... not mess with connecting up an outboard fuel tank, remove the pick up tube from the fuel tank, clear the screen (if equipped), re-install with new anti-siphon valve, install a fresh fuel filter........., and remove this from your P of E list.

We need to routinely check and do these anyway.
 
Had the carb rebuilt. Finially started was getting gas to the carb went on a slow speed harbor cruise all went good. Tried a week latter engine started then stalled wouldnt run. Took it back to the carb shop said little sediment cleaned it out. Replaced the filters reinstalled the carb. Tried to start the motor it would fire for a milisecond and shut off. Have gas when I work the throttle I see the jets squirt but the engine wont stay lit. Just a quick ignition then off again.
 
Could be bad, watery, gas. Is the gas nice and clear with no water? You never said you checked/cleaned the anti-siphon valve either. If you have crossover valves, turn off the valve for the bad engine and open the crossover so it is running from the same tank as the good engine.
 
no cross over tube. separate tanks. same vintage gas. looks good in a jar dumped from filters. think its ignition. both with presto light ignitions. grounded one spark plug wire got intermittent weak spark when cranking.
 
if you have clean fuel in the carb, it is likely ignition...if the prestolite distributors are original, I'd start with the points and condensor, especially if they haven't been touched for a while (weak spark while cranking should bypass the resistor -means check points).
 
Electronic ignition...... as in your original distributors with a conversion kit????? Is so..... conversion kits as in Hall Effect?????

I agree.... with twins we have the advantage of swapping certain components as a portion of our P of E.
Although swapping distributors involves re-setting the ignition timing..... this would have to be your call if you were to do that.


Edit:
I just looked at your profile and I see 1966 californian 28' express.
If these Prestoliite distributors are anywhere near that same vintage, it may behoove you to upgrade them.
Your issue may not be ignition triggering...... but it's certainly time to renew the advancing systems!


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When you "grounded one spark plug wire" did you use a spark plug or an air gap tester? if not, pull the coil wire from the cap and connect the free end of the wire to a spark tester...the other end of the tester to ground and see if the spark is regular and consistent then.

if not, it could be coils or modules...I'd suggest swapping coils as it is faster (usually).
 
None of the above. Inserted a bolt into the boot an held it just off the exhaust manifold. Went by the boat at lunch today and also had the idea of swapping coils. Engine turned over 3 times then started. Running good now. Went to the marine parts shop bought another coil and also bought 2 new distributor caps and rotors. Looking at carbon crust and burn marks on the terminals. should get good spark now. will be changing it out this Sunday before football and ham..
 
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