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The a-4 runs for approx 20 min then starts to miss and eventually dies. After cooling for approx. 15 min the engine will start. Interesting is that as long as I hold the starter button in the engine does not start, but once I release the starter button the engine fires and will diesel for approx 5 sec and then runs for another 20 min before dying again.
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Ray, You are experiencing a rather interesting condition that likely has nothing to do with your engine. There is probably a weak connection somewhere in the primary circuit between the big battery cable and the ignition switch and back to the positive terminal of the coil. During the time of starter cranking, there is not enough current remaining to provide ignition. The instant you release the starter switch, a voltage surge occurs which provides enough current to provide at least a small spark at the plugs, but not quite enough to get the engine to actually start. This condition is normally associated with a weak battery that barely has enough energy to turn the starter over. In these cases, the engine will usually start the instant the starter switch is released. The difference in your case is that the weak primary circuit (and spark) is not the result of a weak battery (you're not reporting such in your message), but a poor primary circuit which doesn't get any better just because you released the starter switch.
What to do: I'd connect a jumper wire (any wire, even lamp cord) from the big battery cable on the starter solenoid directly to the positive terminal of the coil. This jumper is exactly the same thing as turning on the ignition switch so you can't leave it installed indefinitely, just while you are running the engine. If the engine runs normally with the jumper connected, it would confirm a defect in the primary wiring somewhere in the boat.
Don -
engine runs rough then dies
Thanks Don, I will install the jumper cable and see how it goes. RayComment
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engine looses power after 10 min running
Don,
I performed the procedure that we discussed over the phone today. Disconnected the negative side of the coil and read voltage of 12.5 volts. Then I used remote starter and the voltage dropped to 11.5 volts. This seems to indicate the dc ignition system is ok.
Later I took the boat out and was using 1500 rpm for approx 10min when the rpm dropped to 900 rpm. Also noticed the engine temp at 170. But considering its 96 degrees oat and water temp is 87 degrees this might be normal.
I was able to return to the dock at 1000 rpm and no more. When I tried to increase rpm the engine would start to back fire and lose power. At dock side with engine running not in gear, there is a slight miss.
It seems this engine trouble started after I installed the electronic ingnitionComment
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Ray,
On the basis that your problems began after installing an electronic
ignition system, I suggest you review that work. If you installed one of
our Ignitors, it may be that you didn't get the magnetic ring down a full
7/16" from the top of the distributor rotor shaft. If this were to the
case, the spring on top of the rotor will damage the inside of the top of
the distributor cap and cause problems similar to the ones you're
describing.
Things like a loose terminal, spark plug leads out of sequence, could also
cause similar problems.
DonComment
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not able to go above 1000 rpm
Don
I checked the distance from the top of the distributor drive to the top of the electronic ignition doughnut. It measured 5/16, so I adjusted it to 7/16. Then I reset the timing at cruise rpm. The engine ran fine fore about 2min. then started to backfire and would not go above 1000 rpm.
I was able to return to my slip and the engine continued to run rough. At idle the engine was missing and would not accelerate above 1000rpm. After engine shut down, I attempted to restart the engine which was successful but only at idle. I did notice no sighs of fuel in the secondary filter filter downstream of the fuel pump. I then recycled the ignition switch and the fuel pump filled the secondary filter.
The engine ran at idle but would not accelerate. I tried to adjust the idle mixture and was surprised that the engine kept running even after turning the idle mixture in all the way to the seat. Any ideas ? RayComment
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It sounds as though your symptoms are unchanged from before adjusting the magnetic ring. Did you replace the distributor rotor and cap after correcting the location of the magnetic ring?
DonComment
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engine runs rough after 20 min.
Don, I did replace both the distributor cap and rotor be running the engine.Comment
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Does the new distributor look like it has normal wear? I once had a new rotor that stood a little too high and was chunking the cap. Still ran, but not well.
What do the spark plugs look like? Maybe its fuel starved. There is an idle jet and a main jet. Sounds like the idle jet is open, but the main jet isn't allowing more fuel at other throttle settings.Comment
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The most certain evidence of an abnormal condition in your report is that the engine continues to run with the air supply to the idle system completely shut off by the idle mixture valve on top of the carburetor.
This condition doesn't easily explain why the engine won't accelerate above idle, but it will almost assuredly preclude a proper idle mixture adjustment. On the general principle that it's always a good thing to fix something that's broke, I suggest you disassemble the carburetor and see where the air is coming from that's bypassing your idle adjustment needle valve (warped housings etc.). Now and then, fixing one thing has a positive unplanned consequence of fixing something else in the process.
DonComment
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