Engine stalls suddenly?

[smbarcelow]

I had my Ski Sporter out this afternoon and, while we were idling around the lake, the engine cut out briefly (not stalling this time). I decided we should head closer to home, but wasn't too concerned yet. While cruising at about 30 to 35 MPH, the engine cut out again (still not stalling). I put her up on the lift and decided I should make a higher priority of replacing the cable ends at the battery. (I had suspected them of contributing to a problem I had turning the engine over last weekend. This was after having installed a 1,000 MCA battery.) I replaced the ends and started the boat on the lift. It ran just above idle for about 10 seconds and suddenly quit. After a couple pumps of the throttle, it started up again. I ran it around 1,500 to 1,800 RPM's for about 30 seconds before it abruptly quit. I made sure the wires on the ignition switch were tightened down and did the same thing at the distributor. It doesn't sound like it's running out of fuel. I suspect a bad ignition switch. The outside of the switch showed lots of corrosion. What do you think? Am I on the right track? I'm picking up a new switch tomorrow...it's a cheap enough part to replace, even if it's not the cause of this issue. Any feedback is appreciated.

[MOP]

Being as you can duplicate the problem fairly easy on the lift, get hold of a timing light hook it up and hold the trigger and watch to see if it goes out when it dies. Doing that will rule ignition in or out. Ignition and fuel problems can be pesty to separate at times, I have saved a bunch of time seeing if the ignition is dying!

Phil

[smbarcelow]

Great advice! I was pretty certain it was ignition, but I couldn't completely rule out fuel. The timing light would tell me for sure. Thanks.

[Planetwarmer]

I had a similar problem, I replaced the battery wires and that fixed the problem. The ends looked great, but you cant see inside the wire.

Mine had another symptom though, it would also cut out when I put a large load on it. Such as trimming while driving.

[smbarcelow]

I don't have a trimable drive, so I can't test it that way. I may try operating the trim with the engine just above idle on the lift and see if that duplicates the problem. The negative cable had corrision inside the insulation about an inch back from the connector. Could be that the entire length of cable is corroded. I wouldn't even think twice about replacing them if the engine wasn't shoe-horned into the compartment. Guess I'll have to break out the mirrors and driver u-joints. It beats getting stranded out on the lake.

[smbarcelow]

Well, I think I fixed the problem by replacing the ignition switch. It ran for about 15-20 minutes on the lift without stalling. Prior to running her, I replaced the battery cables, too. The old ones didn't look too suspicious, but cables are cheap. Hopefully I'm one secondary accelerator pump away from a fun holiday weekend with her.

[smbarcelow]

I decided to fix my carburetor Thursday night...and got it back on the boat at 11PM. Tried to take the boat out Friday morning and discovered that I had changed the carb settings too much for it to stay running. In the process of trying to tune the engine, running it on the lift, the oil pressure sensor failed and starting pumping the oil out of the engine. (We discovered this once the lifters started collapsing and making a bunch of noise.) The good news is, had we been out on the lake running it, the loss of oil probably would have resulted in significant damage. Anyway, I've got more work to do to get the boat running again...

...but I still own a Donzi. :biggrin.:

[smbarcelow]

Well, my dad and I replaced the oil I lost last night and turned the engine over with the distributor disconnected (to prevent the engine from running). While we turned it over, we watched the oil pressure sensor and observed oil pumping out between the sensor and the block. (As an added bonus, I'm hoping that I got those lifters pumped back up.) After removing the sensor, we found that it had an adaptor fitting to fit the SBC thread. Well, the female end of the fitting didn't quite fit the male thread of the sensor, so it was assembled with Teflon tape and over-tightened. As a result, the fitting cracked, hence the oil leak. I was happy to discover this, as the thought of a sensor failure potentially ruining my engine didn't sit well. I'm going to see if I can buy a new sensor that operates in the correct range for the gauge and fits into the SBC block without an adapter. Anyway, I thought I'd post this update...you never know when it might come in handy for someone else.

[MOP]

I like Teflon tape and paste but many people do not realize just how slippery it is, it is unbelievably easy to split a fitting as the Teflon steals so much of the feel for tightness. Two wrap is the max on fitting and use only the paste on any type of electrical sender to insure proper ground.

Phil