Diesel episode yesterday.....Ideas?

[gwp]

Universal M25xp
Yesterday while not paying much attention....ran aground. To my surprise, I backed off successfully and was underway in no time. However, after a minute or two motoring into thicker water, I noticed the engine rpms seemed to drop as if it was starving for fuel but suspected that it was my imagination. Killed engine and sailed for a while longer then when time to start up again, had to crank engine quite a while before it finally began to "catch" and sputtered to a start. blueish black smoke emerged for the first few minutes then cleared and ran great back to the dock. Ok...........Changed primary racor filter and secondary within ~25 hours ago (maybe 1 year ago). Tank was removed and cleaned couple years ago and I keep biocide in fuel and air filter clean. I'll certainly change filters right away but the smoke really concerned me. Any ideas as to why the smoke and what could have happened? Thanks

[hump180]

Did you run aground in kelp or heavy weeds. If so you could have fouled the prop, hence what sounds like an engine overload condition.

[Mike and Joanne Stimmler]

Did your temp. go up at all?

[Ron Hill]

gwp : It sounds as though the grounding and the blue smoke maybe unrelated!?

You probably did the correct thing by changing the Racor and engine mounted fuel filters. 

You failed to mention if you had a blue smoke problem after you changed the filters?

The usual causes of blue/black smoke from the exhaust are : engine overload, insufficient air and excessive fuel (too much throttle?). Keep us posted. 

A few thoughts 

[tonywright]

A few years ago we ran aground in the IC waterway in Florida with a charter boat. After backing off we had some overheating and smoke. Found that the raw water filters (twin engine cat) had sucked up lots of sand and were partially blocked. Next time I back off a sand bank I will check this carefully. Always best to make mistakes with someone else's boat!

Moral of the story: any chance you sucked up some sand or silt? (although overheating will usualy produce white smoke rather than blue).

Tony

[gwp]

The grounding probably wasn't related, as I just can't imagine any scenario supporting this theory but thought I'd mention it just in case anyone disagreed. Probably just chance that it happened right afterwards. Engine remained at normal temp the whole while. Don't think the prop fouled on a crab pot cause it probably couldn't have cleared itself without my help and no seaweed or anything of the like. The smoke slowly cleared over a period of just a few minutes and the engine ran normal on the way home. I haven't changed the filters yet but will before next sail. Just wonder what could cause "momentary" dark smoke? Remember.......it was very hard to start right before the smoke, but then cleared up and ran normal. Thanks much for the ideas

[2ndwish]

Is it possible that in the heat of the moment, you started the engine in gear? That would explain the behavior.

[Bobg]

last summer my engine belched out a lot of blue smoke and died, it wound up being a plugged screen in the fuel tank pickup tube, which I removed.  Engine runs fine now

[Stu Jackson]

last summer my engine belched out a lot of blue smoke and died, it wound up being a plugged screen in the fuel tank pickup tube, which I removed.  Engine runs fine now

For those of you with new-to-you boats, we put together the CRITICAL UPGRADES topic sticky, which includes this:  http://c34.org/bbs/index.php/topic,5078.msg32615.html#msg32615

Please take a moment to read them and act accordingly.

Your boat, your choice.