Tech advise needed -- strange engine happenings

wind dancer · February 19, 2007, 01:53:39 PM

My family and I were heading back from a weekend in Kingston this morning, and (in a Small Craft Advisory, no less) our engine cut back to idle and then died just outside of Shilshole Bay (30 knt gusts). We through our jib up while I tried to figure out the problem. Fuel was fine, oil was dirty, but ok, engine temp and water flow were fine. No obvious problems. I even checked for air in the fuel line. At the time this happened we had been heading into the wind (and 4ft swells -- I love that kind of weather, btw) at 3-4kts headway, under full power. I got the engine started back up fine, but once again, no power. I was losing headway. We took the safe way out and accepted assistance from some fine folks with a working power plant, and moored at the Shilshole Marina Fuel dock for a half hour while I further ruminated on the subject. I then started her up, through her in reverse, then in forward. No problems at all. We then proceeded to power through the locks, and opened three bridges on our way back to our moorage with no additional symptoms.

My thoughts: I possibly had something wrapped around my prop; my tranny is acting up/overheating (no temp sensor on that one); or I got some backpressure at the exhaust due to the nasty weather (note that everthing worked fine after I was in protected waters).

Any thoughts or suggestions?

Gary · February 19, 2007, 02:22:54 PM

When you're boat is moving around a lot in wave action the fuel contaminates mix in with the turbulance. I would check out the fuel pick up tube in your tank. If there is still a screen on it's end, take it off. That may be a source of temporary and intermittent blockage. Then, remove your fuel from the tank, then remove the tank for cleaning or replacement. This whole situation sounds like you're primary and secondary filters are doing their job for the engine but the pick up tube, fuel and tank could do with some cleaning.

wind dancer · February 19, 2007, 02:39:54 PM

Thanks Gary. Sounds like a great place to start.

sail4dale · February 19, 2007, 02:54:12 PM

had the pickup tube/screen problem on my Cat 30 and it was just like you describe. However, are you sure your filters are clean?? remember looking at oil in a bowl and it looks clean is deceiving.

your eye can only detect dirt above 40 microns, and the filters take out dirt particles down to 10 microns (depending what filters you have). I have 20 and 10 micron filters. The 20 is the Racor and the 10 is a spin-on at the engine. The spin on is a faith filter with no indicator of it's condition. A vacuum gauge on the fuel line after the filters would give you the real story, especially when at full power.

Ted Pounds · February 19, 2007, 03:00:20 PM

I agree. It sounds like fuel starvation. Been there, done that, got the T-shirt. Start with the pick-up tube as reccomended and work your way down the fuel system changing the filters, bleeding etc. Good luck.

Stu Jackson · February 19, 2007, 03:14:33 PM

How full was your fuel tank? With all that rockin', you could have just picked up a blob of air which shut you down. It would explain why it worked later on. Even if all the other issues discussed here, which are certainly valid, don't resolve it to your complete satisfaction, it could be a partly full tank just got enough air in the line.

wind dancer · February 19, 2007, 03:27:54 PM

I filled the tank two days prior. I thought it might be air in the lines too, so I purged some from the Racor and reprimed it (though I didn't do a terribly thourough job of it, time was short).

Ron Hill · February 19, 2007, 03:33:17 PM

Jay : You initially had the "text book" symptoms of a clogged pick up screen in the fuel pick up tube. However, after that you got the engine running, you should have had the same symptoms again. IF your electric fuel pump wasn't working, the clogged pickup tube/filter/s stopped the gravity feed of fuel!!

No doubt you need to drain your fuel tank and clean it (see my Mainsheet article). When you remove the tank make sure that you don't have a screen in that fuel pick-up tube (my other Mainsheet article on that very topic). Then change both filters (also look at the screen in the fuel pump!!), bleed the system and you should be "good to go". If you have the old original electric fuel pump you may want to change it to the new electronic model (take your old pump to a NAPA auto parts store to match a the new one)

Your dirty fuel tank, after 20 years did that "Dasterly Deed".

wind dancer · February 19, 2007, 04:28:52 PM

Another item I just remembered. . . the throttle backed off and litterally couldn't be forced forward? Is this symptom common of fuel starvation/plugged fuel pickup? This problem is new territory for me. Thanks for all your help!

Stu Jackson · February 19, 2007, 05:24:29 PM

Ah, more input! Could something down below have rammed into the cable connecting the throttle to the linkage on the engine? Or something amiss inside the binnacle...

wind dancer · February 20, 2007, 07:00:55 AM

Not that I could tell. It was more like the compression of the engine was forcing the throttle back. As the engine lost speed the throttle pushed back against my hand, and when I tried to speed back up, it wouldn't move.

Ron Hill · February 20, 2007, 03:37:23 PM

Jay : If you can not find anything externally that caused the throttle problem, I hate to be the bearer of BAD Tidings. You'd better have a GOOD mechanic look at your injector pump (it also is the key to engine timing) BEFORE you try starting/running that engine!!
(The throttle cable at the engine connects to a pivot arm, the other end of that arm connects to the injector pump.)

wind dancer · February 20, 2007, 04:13:34 PM

Ron:

I've already run the engine for another hour or so. . . with no problems, or additional symptoms. Also, the engine never ran rough at all, it just slowed down. So, I don't think the injector pump is the culprit. If it were, my timing would be noticably off, correct?

David Sanner · February 20, 2007, 05:02:20 PM

A lot of good suggestions... I agree, it sounds like it's either the
linkage or something with the injector pump.

Looking at the parts manual I think it would have to be in
either the "Speed Control Plate Group" or the "Governor Group."
http://www.c34.org/manuals/

The timing (as Ron noted in his Injector Pump Rebuild Project)
is controlled by shims that the pump is mounted on.

Let's hope it was something in the external linkage.

wind dancer · February 21, 2007, 10:11:35 AM

I've done a lot of work to the boat since I bought last fall. One of these projects was a replacement of the stock alternator with a Balmar alternator and Xantrex/Balmar voltage regulator. The voltage regulator sends a signal to the tach. Is it possible that in the rough seas I encountered this connection came a bit loose and if so, would the tach signal effect the governor? I did a cursory check of the wiring at the time. I have noticed that my tach reads a little higher than before, around 800-900 rpm at idle.

Also, if the voltage regulator could be affecting the governor, how about heat? I placed mine in the back of the engine compartment, which generally stays pretty cool, but I had been running the engine hard for over two hours when the problem arose. . .

Just thinking out loud here. . . as usually all advise is appreciated. I'm going to drain all fluids, replace all filters, remove the pickup screen and take a fuel sample from the bottom of the tank this weekend. I might also replace the water pump impeller if I have time, though cooling isn't a problem.