Engine quits.

[AlbertJ]

Yesterday my A4 started quitting. This happened on the way back to the marina. This is the first time I have had problems with the engine since I bought the boat 2 years ago. The engine would run fine for 30 sec to a minute. Then it would quit. I was able to re-start the engine every time with no problems and finally got back to the dock after 10 or so restarts. Any help would be hardly appreciated!

Thanks,
Albert

[JimG]

This might be off base, but it sounds like maybe your fuel filter is dirty or fuel pump is failing. When you turn on the pump, it fills the carb bowl slowly, the engine then starts, and the engine "outruns" the fuel supply, stalling when the bowl empties. While you're going thru the motions of re-starting, the fuel supply begins catching up, and the cycle repeats. Try shaking the fuel filter a bit.

I assume the oil pressure and temperature are within bounds?

[AlbertJ]

Jim,

Your suggestion makes a lot of sense. The water temp was in 140s which is normal. The oil pressure gauge is broken so there is no way for me to check on that. The only think that was suspicious is that the engine would start right away, within a second or two from shutting down. I will check on the fuel filter the next time I am at the marina.

Thanks,
Albert

[Don Moyer]

In addition to the good suggestions from JimG, if you have an electric fuel pump, you might check the fuse between the coil and the pump. Or the pump itself may have failed. Many boats have tanks sufficiently high so that gravity will provide just enough flow to the float chamber to allow the engine to run for a few seconds, and then quit.

Don

[Jon Remy]

Albert, this sounds exactly what my Cal 34 is doing. Runs forever on the mooring, then underway quits every couple of minutes but starts up great every time.

[Dmann]

Like Don said, check the fuse between the coil and the oil safety switch. If you keep blowing fuses, chances are your oil safety switch has shorted out. This will tell your fuel pump to shut down everytime. Just remove your safety switch and take it to a auto parts store. For about $15 you can get a new one , reinstall it and your engine will stop quitting. Good luck!

[SimonP]

Again I'm so glad this forum is here, thanks Don!
Last week I ran a series of tests on my engine (compression, timing, etc). Tested fine. This week, I went to start it, at mooring. Started fine as usual, then quit after 30 sec. Fifteen subsequent tests were the same, started fine, ran smoothly (variously at at 1000-1500 revs), died in 30-70 sec.
It has a new carb and a new fuel filter, new distributor, wires and plugs.
Its not clear to me whether its an electrical failing or a fuel supply failing. Are there parts of the ignition that could build up a charge or become non-conductive, with heat or time? What tests should I do?
I did notice that the three wire contacts onto a ~1" hex thingy which is screwed into the block just aft of the fuel pump (oil pressure sensor?) were corroded and wiggly. I will pursue the suggestion of Don and DMann, any other advice, suggestions of discussion?
thanks!

[SimonP]

posting "Engine Quits Suddenly"
http://www.moyermarine.com/forums/showthread.php?t=80
describes symptoms like mine, and Alberts.
WC notes "It was at this time I noticed and remembered the little 10a, in-line, fuse holder on the lead to the low oil pressure cut-off switch...I replaced it ... It was fixed."
Looks like I need to go over the entire oil low pressure cut-off switch and related parts...
SP

[Don Moyer]

Simon,

The fitting just behind the fuel pump is most likely your oil pressure safety switch. Loose connections on this switch would shut off your fuel pump and definitely explain your symptoms.

Don

[P10M]

I have trouble with the fuse between the fuel pump and oil pressure safety switch. If my oil pressure goes above about 40 (which it will do if revved much above idle when cold) the fuse will blow. It is fine otherwise. So the question is, why would the fuel pump need to draw more amps - enough to blow the fuse - when oil pressure is high?

[Don Moyer]

P10M,

I'm not sure what size fuse you are using, but Facet's latest fuse recommendation for our model pump is 5 amps. They used to allow up to 10 amps maximum but they lowered the recommendation on their current labeling approximately one year ago. The normal current draw of the pump is approximately 2 amps.

Based on pure speculation, if you have a wire connecting the "R" terminal on the starter solenoid and the oil safety switch, I'd remove it. We have had a few mystery fuse failures that were believed to result from inductive back surges from the rather large coil in late model (Delco) starter solenoids.

If the fuses keep blowing, I'd also move the incoming power lead to the oil safety switch that usually comes from the positive terminal of the coil and connect it to the large battery cable on the starter solenoid. The Facet pump company has on several occasions questioned our convention of connecting the power lead for the fuel pump directly to a terminal on the ignition coil.

It would be very interesting if it turns out that moving the power lead away from the ignition coil corrects your problem. We would have to do a bit of quick research to determine whether or not the battery master switch meets the Coast Guard requirement that electric fuel pumps be connected to a "switched" power source.

Don

[Unregistered]

Don,

Thanks for the reply. I'm currently using (and blowing) 5 amp fuses. I don't believe I have a connection between solenoid and safety switch, but will check.

I'll will try moving the power lead from the coil and post the results here.

I remain curious about why this is only a problem at higher (above 40) oil pressure.

Thanks,
P10M

[Don Moyer]

I have the same curiosity. Instead of focusing on oil pressure variations as a function of RPM, perhaps we should be looking at other things that change along with oil pressure. For example, have you ever measured the DC voltage in your system while the engine is running at different RPM?

Don

[P10M]

Don asked "...have you ever measured the DC voltage in your system while the engine is running at different RPM?"

Are you talking primary circuit? I've monitored voltage at the battery on occasion and have never seen anything unusual. Should I measure somewhere else?

[Don Moyer]

P10M,

I guess I didn't make the point clear enough, which is that the entire DC system should be indicating at least 13.2 volts any time the engine is running, which is the alternator voltage. If you're only reading 11 volts (especially at the batteries) it means that the alternator is not working.

The only case where an individual electrical component (like the primary ignition coil) would indicate less than 13.2 volts would be if the current draw to the coil exceeds the current carrying capacity of the wire leading to the coil. In this case a "voltage drop" will occur at the coil and the voltage at the coil might drop to as low as 11 volts. While the engine will still continue to operate with this voltage, any other equipment connected to the coil that needs more than 11 volts will not.

Don

[P10M]

Re: blown fuse pump fuse when oil pressure high.


O.K.. Over the weekend I got a chance to check out voltages and may have found the problem. Voltage at the coil is dropping well below 11 volts at startup. We have an old "AutoMac" voltage regulator which has a manually controlled field current control. We are in the habit of turning this all the way down when cold starting the engine and then turning it up after a bit of warmup. Apparently when it's all the way down, it doesn't exite the alternator at all and there is no alternator output. Interestingly, the fuel pump fuse did not blow while observing this low voltage at the coil. We did another cold start (the next day) and revved the engine up enough to produce high oil pressure (45) and the fuse still did not blow. So now I'm guessing, as you suspected, that oil pressure has nothing to do with this problem (unless it's the oil pressure safety switch itself that is the problem.) In any case, I'm going to reroute the lead to the oil pressure switch as suggested previously and monitor the situation. I will also consider updating my regulator, or at least make sure it's on when starting the engine.

[awesomepossm]

Yesterday my A4 started quitting. This happened on the way back to the marina. This is the first time I have had problems with the engine since I bought the boat 2 years ago. The engine would run fine for 30 sec to a minute. Then it would quit. I was able to re-start the engine every time with no problems and finally got back to the dock after 10 or so restarts. Any help would be hardly appreciated!

Thanks,
Albert

I have had this problem with my atomic four. The float valve inside the carburetor sticks closed, the bowl goes dry and the engine quits. This could cause the symptoms you are describing. My valves is so sticky that sometinmes I have to tap the carb with a screwdriver to free the valve. If this is your problem, it is hard to find. If you have good fuel flow and pressure, it is in the carburetor. Easy way to check fuel flow is to disconnect the fuel line between the carborator and pump. Route the fuel line into a clean container and turn on the ignition. Be careful of course not to spill the fuel. If you still have a mechanical fuel pump crank the engine for 15 seconds. Fuel should flow freely. If it is not the fuel, it is the carburetor. Overhaul the carb.

[Kurt]

Or, with a mechanical fuel pump, you can simply move the priming lever back and forth to check for fuel flow as opposed to cranking the engine. This is the way I usually check for unobstructed fuel flow (with the line to the carb disconnected) or flush the main jet/bowl (with the line attached to the carb and the carb drain nut off) - sort of an annual maintenance item.