Boating How-To’s - DF140 not firing on 3 cylinders

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View Full Version : DF140 not firing on 3 cylinders


lissenung
06-07-2012, 05:27 PM
Hi everyone,

I'm new to this forum, at least as a poster, I've been reading a few previous posts and they have helped me a lot. My husband and I live on a small island in Papua New Guinea, where we own a SCUBA diving resort, so our boats and engines are very important. Unfortunately, there is no Suzuki dealer in town nor anyone who has any clue about 4-stroke engines, so out of necessity, I had to learn by doing.

I have searched the internet left, right and centre, but cannot find anything about that would help me with my current problem.
On a Suzuki DF140 4-stroke, the oil pan cracked, so I removed the cylinder head cover, then removed entire engine block in one piece from oil pan and replaced oil pan with that from a very dead engine I've still got lying around. We bonded the engine block to the oil pan, tightened all screws, put the cylinder head cover back on, tightened to specs, engine wouldn't start, but gave a MAP1 sensor code, so I replaced the sensor and code is gone, but engine still won't start. No other codes, just total-running-hour beeps/lights.

It sounds like it's firing on 1 cylinder only, every now and then it coughs, then just cranks without firing. We checked spark plugs although they are brand-new plugs, and they don't look like they've done any sparking, ie. very clean and dry. Power to starter motor is fine, even when cranking. Took injectors off and cleaned them, although they look pretty good, replaced them and cranked the engine without the injectors plugged into the cylinder block and all 4 injectors spray petrol okay, so installed them properly and to specs. Finally, we measured the compression and there you have it, all 4 cylinders read only 75 - 90 PSI. We followed instructions on how to measure in the repair manual, so reading should be pretty accurate. In any event, compression on all cylinders is way less than the min. 185 PSI it should have.
Took manifold off and replaced manifold gasket, tightened bolts to specs but still no go. There was a bit of carbon build-up in the manifold, but nothing was blocked.

Now if that was one cylinder that wasn't firing, I would have some idea on what could be the problem, i.e. crack in the cylinder head, valve or piston damage etc., but all four????? The engine has only been out of use for 8 months and other than the cracked oil pan, we had no problems with it. Oh yes, new LP and new HP fuel filter also installed and, not that this matters to the problem, but new oil filter and new oil.

Any suggestions? We never took the engine block apart, not even the flywheel, just took the whole thing off one engine mounting and put it on another.

I've spent days on this engine, but just can't get it going, so any help is much appreciated.

Thanks,
Ange


Albiemanmike
06-11-2012, 06:45 AM
Compression and spark are two different issues. The spark problem I would think would be caused by something you forgot to reconnect or bad connection issue. The compression issue could be many things but you said you removed the cylinder head again and replaced the head gasket. What was the compression after head gasket replacement? Removing the cylinder head would entail that you have to remove the timing belt. If you did not get the timing belt reinstalled properly that would surely cause you all kinds of grief. I would check compression again and then remove the timing belt and position the crank in the #1 firing order or whatever Suzuki says to put it in for reinstallation and then turn it by hand to make sure you got it installed properly and do not have any valve clearance issues before you actually try starting it.

Also I am not really familiar with the Suzuki's but if you installed the timing belt improperly and tried to start the motor you could have possibly bent some valves which would also cause you compression problems among other things. I don't know if Suzuki motors have interference free valve trains or not but if they are not then you could have some big valve train issues gong on.



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