Engine Bogging Down

[sailorboy103]

I am hoping someone can figure this one out - A while back I replaced my ignition system with the Indigo electronic ignition off of my old A-4 that got scrapped due to block problems. The new engine came with the original ignition, and never started as well as my old engine used to so I put the electric fuel pump on it as well as the "old" electronic ignition. The problem I am having is that if I am running the engine in neutral ie: engine test,
charging batteries,etc." the engine runs fine even for extended time- about 2 hrs. I get underway, and after about 1 1/2 to 2 hrs operating at approx. 1/3 throttle ( with all parameters norm.) the engine will bog down to about idle speed and adding throttle does no good. If I shut her down for about 45 min. she will then run fine for the about 15 min. it takes to get into my slip. I do not know if the problem would re-occur if I ran it longer - haven't tried it.
While the engine is bogging down, if I put her into neutral ; it again runs very well and with very good throttle response. I don't see how it could be a timing issue due to the 2 hr. time lag before the problem presents itself.
Does ANYBODY have any thoughts on this mystery?HELP!

[Dave Neptune]

Well sailorboy, it sounds like a fuel delivery problem maybe! Have you checked the plugs just after or during an episode? If it were electronic it would PROBABLY just shut down not slow or bogg. It could be as simple as an air leaking into the fuel stream after things warm up good causing a little starvation ( a clean plug almost white) or a rich condition via fuel preassure to high causing a fouled plug ( black and sooty) which is doubtful. If it were seizing it probably wouldn't go back to idle, very doubtful.
We'll need a little more info, however bogging is usually a lean condition or timing which I doubt as it takes a while to develope, Im betting so far that the beastie is leaning out after your two hours or so.

David Neptune

[sailorboy103]

Thanks for the come back. Thats a good idea to check the plugs for cues as to the problem. To give you a bit more to go on:
* the engine I have is an old model
* I previously had a hard starting problem which I believe I solved last weekend by removing a (now) stuck shut, fuel anti-siphon valve. After removal the engine started and ran (in neutral) better then ever.
*Due to the layout of this engine ( flat steel cover plate over the flywheel and a PTO wheel for the heat exchanger pump) I did not have easy access to the timing mark when I changed up to the electronic ignition, so I did it the old trial and error way. If all else fails I will clear the front end, pull the cover and cut a window so I can see the timing mark.
In spite of the " non precision" setting of the timing; I [U]think[U] I got it right due to the engines running VERY well both in no load and (for a couple hours anyway) in load condition. I'm willing to concede that the timing might be the problem, but why then does it work very well for even 2 hours?:confused:
* as a last point I might mention that due to life interfering with whats REALLY IMPORTANT - The boat sometime sits for about 2 sometimes 3 months without my being able to visit her. I know, I know:
I'm a BAAAD Daddy! I know this is slanderous, but sometimes there are things MORE important than sailing !? :eek:
Anyhow - thats about all for any further clarification I can add.
I will check the plugs, fuel flow (though I have faith that it is perfect now); and if you think it is a flaw in my timing I will fix things so I CAN do the "timing light thing" Mucho Gracias for the assist - EXCUUUSE ME!- I meant " Mahalo and Aloha Nui. :D

[dvd]

I would check the fuel filtration system. Sometimes when they sit the sediment/junk in clogged fuel filter loosens up but when you get on it again for a while it will clog back up. Worth a shot.

dvd

[Marian Claire]

Does it bog down gently, any backfiring? Do you have a primmer bulb? Is your coil located on the engine? A primmer bulb could help determine if the problem is an air leak before the carb. The coil could be getting hot and failing .Just some ideas. Dan S/V Marian Claire

[sailorboy103]

Wow -I really appreciate the responses here thanks!:)
Now to respond to the responses:
dvd : the fuel filter is a good idea - I shoudda thought of it myself, what with the boat sitting for extended periods like she has. I have some spare filters so I will give it a try, thanks.
Marian : As to the bogging problem, it comes on suddenly. I was chugging along happy as a clam ( ARE clams happy? If so, WHY?! Don't they know we EAT THEM?!) Anyway- after about 1 1/2 to 2 hours of normal motoring along at 1/3 throttle, she suddenly dropped to about idle speed and stayed there. Increasing throttle did nothing, however if I put her into neutral my little sweetie was like "Problem?WHAT problem!" the RPM's went back up and the throttle response was fantastic ( as long as I was in neutral). The operating parameters (oil pressure, engine temp) were normal. Being as there was no wind I had to motor back across the bay (again - about 2 hours) and other than the snail pace I was moving at, the engine showed no sputter,stutter or other crude behavior. One thing I did notice after about an hour I checked the engine temp and it had gone DOWN a little bit ( AHA - a clue, to what?)
any way I dropped the hook outside the marina, and after waiting for about 45 min. the engine started up and worked like there never had been a problem
which was nice 'cause I'm really allergic to engines going kaput as I'm approaching my slip!
I DO have a primer bulb on the fuel line, which is how I discovered the screwed up anti-siphon valve in the first place. I removed that naughty little rascal and the line charged up in only 3 squeezes and held pressure.
As for the coil, I have it on the engine and it has never given me any grief there. Even though the engine does not run hot, it could try putting rubber or wood spacers under it to see if that helps. Really don't see where I could move the coil to.
I shall try both ideas of replacing the fuel filter, and try to insulate the coil from the engine heat. Being I'm out in Hawaii, maybe I can get a Kahuna to un-hex the engine for me too! Hey ! I'll try almost anything!
Again - Thanks for the responses out there. Appreciate any help I can get.
Mahalo and Aloha

[Kurt]

Whenever I hear of an A4 running fine in neutral and bogging occassionally in gear under load I think fuel delivery problems first. Taking the carb off and giving it a good cleaning would be my first step, especially if you have not had an in-line fuel filter on your boat (did I read that correctly?). After cleaning the carb, I would certainly add an in-line filter - and a fuel water separator if you don't have one, of course. Cleaning the carb is easy and should probably be part of your troubleshooting process.

[sailorboy103]

Thanks Kurt - I recently (about 4 months ago) did a cleaning of the fuel tank,filter and carb. I replaced the fuel lines at that time also. I'm really starting to believe it is a timing problem -tho I don't get why it wouldn't act up from the moment I put the engine under load.

[Marian Claire]

Check out the "sticky" Don posted on "some comments about coils". He talks about the higher temps caused by electronic ignition compared to points. That was one thing that has been changed on the boat if I understand correctly. I had an air leak, before the carb, problem in the past. The engine would run fine then RPMs would drop and she would die. By pumping the primmer bulb she would return to normal. For awhile that is. I have a water separator and a clear, glass, inline filter just before the carb. [Edit; The clear glass type of filter is not CG approved] I can visually watch the flow of fuel. At least as far as the carb. There is a big difference in the demands of under load and Neutral. During my most recent adventure she would run any RPM, 800 to 2600, in neutral but would almost instantly die if in gear and pushed above 2000+- RPMs. Keep the info coming. Dan S/V Marian Claire

[Kurt]

I think timing might be a stretch. I have had numerous timing problems and they will show up right away under load. Air leaks in the fuel system are a possibility. Coil I am unsure of - I have had no problems there, but you should have a spare one around anyway so it's an easy thing to troubleshoot - just put another one on. Remember, however, that even though you cleaned the carb 4 months ago doesn't mean you don't have a tiny speck of something in there causing problems now.

[Marian Claire]

Ditto what Kurt says about the carb. Any work up stream can send something unwanted to the carb. Dan S/V Marian Claire

[sailorboy103]

Rodger-Dodger and thanks to all ! I have a "things to try" list and hopefully in a couple days I can break free from tasks around here and will at that time try them all. Again, THANKS-I will post any results(hopefully positive!) when I have them. Mahalo:D

[sailorboy103]

Update to my prior post. Thanks to all for their assistance. I changed the fuel filter and the coil ( the existing one was the Indigo supplied coil) and now just need to find the time to get out and get some run time on the engine and see how things go. Mahalo and Aloha:)