Yanmar 3GM 30F stopped while motoring, won’t re start.

[skipperpete]

A friend of mine had a Saildrive repair done then set off on a short trip but less than an hour underway, one engine cut out and refused to restart so he returned to the dock and despite being a pretty good mechanic himself he got the Yanmar mechanic to investigate but after a lengthy intervention the 3GM refused to fire up. The mechanic did a compression test and all cylinders were about 380psi and then removed the injector pump and sent it to the fuel injection tech for a run on the test bench and it got a good report so refitted it.......and tried for a start with “Start ya bastard”.... no luck, then the holidays began and the service provider became un available so the owner started to troubleshoot the problem himself. So here’s the list of what he’s done over the new years break.
Connected a can of clean fuel to the primary filter.
Added a squeeze bulb to provide a bit of pressure.
Checked all the usual. (Oil ,coolant,belts, battery and connections
air intake and filter)
Drained the Aqualock
Inspected the mixer elbow
And took a fuel sample from the tank( it smells “weird” but will burn if a tissue soaked with it is lit) ??
And with the mixer to aqualock hose removed he is getting a lot of smoke while cranking....... still no start.
We’ve been chatting on the phone about what to do next and
“I got nuthin” so thought I’d run it past you guys for inspiration and advice.
Pete.

[gonesail]

is that the engine with a mechanical lift pump? probably not the problem but worth checking.

[GreenWave]

Any chance water got in the fuel? I don't believe in coincidence so would be trying to tie the Saildrive service to this problem.

[donradcliffe]

If it isn't compression and the starter is turning it over, then it most likely is fuel or a blocked exhaust.

Did he bleed the high pressure lines to the injectors?

Did he test the injectors?

[Wotname]

Crikey Pete, if you 'got nuthin', the guy is up the proverbial creek in a barb wire canoe without a paddle.

Time to go back to basics and recheck the only three requirements - fuel / air / compression.

Fuel - gravity feed a container of fresh clean fuel directly to the IP, pull an injector and observe the spray pattern. Alternately mist spray diesel (by hand) into the air intake while cranking to confirm if fuel is entering the cylinder.

Air - remove any air intake filter. Physically check for any obstruction in exhaust manifold and disconnect exhaust hose at the manifold.

Compression - check compression reading on all cylinders and starting speed rpm. The easiest way to confirm sufficient starting rpm is to spin the engine up with all 3 cylinders decompressed for say 5 seconds and then recompress 1 cylinder. If no start, repeat but recompressing a different cylinder.

Fuel and air always required, compression is only required to ensure there is sufficient heat for initial combustion to occur. While is fairly easy to ensure the presence fuel and air in the cylinder, it is harder to ensure sufficient heat is being created by the compression process. To confirm if the absence of heat is the problem, direct very hot air into the intake by using a electric painting stripping tool ('hot air gun').

The only thing left to check is timing!

Please let us know what the final fix turns out to be!

[skipperpete]

All good suggestions, the catamaran owner has explored most of the suggestions made here so far and fuel is definitely my main suspicion but I would have thought a Yanmar mechanic would have eliminated that line of thinking in the first 10 minutes. I’m actually in the same city as the boat, but 40 miles away from it ( there might be a personal visit coming up).
I’d like to see the valves and do a quick timing check but from past encounters its a bugger to work on, the engines are both amidships under the galley on one side and a benchtop on the other with the saildrives on an athwartship angle in the tunnel.
I really like the heat gun Wottie, after the fuel its the next move and I’ll definitely post with the results over the next couple of days. Thanks for all the suggestions.
Pete

[Wotname]

Most (but not all) faults are related directly to the observed symptoms immediately before failure and then to recent previous maintenance activities.

From what we know from the OP, the engine started and ran for up to an hour under normal load then died. As there were no reports of abnormal conditions, no over heating and no alarms, then this highly suggests a fuel failure. It certainly does not suggest a compression / enough heat issue but you never rule out anything.

For an engine to simply stop without warning (missing, running roughly, dropping rpm, losing power etc) also suggests the fuel supply was suddenly interrupted.

It is hard to see how the sail drive repair could affect the failure to run or start but it could be assumed the sail drive repair necessitated engine removal, if so was the engine correctly reinstalled.

[Excalibur5]

To ask a loaded question - have you tried using a TINY amount of ether (starting fluid)?



As the GM series have no built in pre-heat system (glow plugs or the like), I have noticed in low temperatures my 3GM can be very difficult to start. As soon as the temperature was over 65F; it starts easily, but in lower temperatures, I have to crank it for a bit to get the cylinder temperatures up a bit from compression.


Personally, I've never had to resort to ether on mine, but in near freezing tempertaures nearly have used it. I do carry some for just-in-case emergency starting. To use, give just the barest spritz (as in point the nozzle and push down just long enough to start the spray and immediately stop) into the intake then crank the engine over. If it fires right away but doesn't continue running, it is likely fuel related. It might start right up..


But be very careful to use only a tiny amount - too much can break rings or cause internal damage. And don't generally rely on it for starting. If it requires it every time, it's a sign your compression is getting low.

[Wotname]

^^ the reported use of "Start ya bastard" is an ether based starting fluid.

OP is in mainland Australia (likely North Australia) and its mid summer here. Ambient temperatures are above 80F, often well above.

[Excalibur5]

Originally Posted by Wotname

^^ the reported use of "Start ya bastard" is an ether based starting fluid.

Gotcha! Didn't pick up on on that, sorry!


I'd be suspicious of fuel or injection issues - tried pulling an injector out, connecting it to a line, turning the engine over, and verifying it's indeed spraying fuel? A jammed stop rod (can be either a solenoid or a pull cable on the fuel pump) will also shut off all fuel flow.

[skipperpete]

Originally Posted by Wotname

Most (but not all) faults are related directly to the observed symptoms immediately before failure and then to recent previous maintenance activities.

From what we know from the OP, the engine started and ran for up to an hour under normal load then died. As there were no reports of abnormal conditions, no over heating and no alarms, then this highly suggests a fuel failure. It certainly does not suggest a compression / enough heat issue but you never rule out anything.

For an engine to simply stop without warning (missing, running roughly, dropping rpm, losing power etc) also suggests the fuel supply was suddenly interrupted.

It is hard to see how the sail drive repair could affect the failure to run or start but it could be assumed the sail drive repair necessitated engine removal, if so was the engine correctly reinstalled.

You’re totally correct Wottie, no noise , no surging, no alarms ,just cut out.
I’m with you on reviewing whether a connection exists between the previous work and the un expected shutdown, I initially thought maybe something simple like crossed fuel lines (I don’t think there’s any way to do the saildrive without lifting out the engine completely) but at the moment anything is possible.
The injectors were out for the compression test so it would have been logical to pop test them at that time but I don’t know if they did. The HP pump was definitely tested.

[skipperpete]

Yep, boat is in Queensland

[chris mac]

Is it possible the kill cable got pulled or shifted enough to kill the engine? This would explain why it isn't catching with the ether, or fresh diesel.
I've had mine (3gm30f also) not start because the cable was out about 1/4". Very frustrating to say the least, but easy fix at least

[leecea]

Does the other engine still run and does it share the fuel tank?

[Wotname]

Originally Posted by chris mac

Is it possible the kill cable got pulled or shifted enough to kill the engine? This would explain why it isn't catching with the ether, or fresh diesel.
I've had mine (3gm30f also) not start because the cable was out about 1/4". Very frustrating to say the least, but easy fix at least

That is a good thought, especially as it likely the engine was removed and reinstalled and if access is tight, perhaps the kill cable was not refitted correctly and something caused it to move sometime after running. This would explain the engine simply stopping suddenly while underway.

BUT... the HP pump has since been removed for testing and refitted. It is hard to imagine the guy refitting it would refit it with the stop cable actuated although anything is possible.

Another left field thought - there are 2 different faults. The first stopped the engine while underway and the second is now preventing the engine from starting.

1 - the stop cable moving (while running) killed the engine initially.
2 - after the HP pump was removed for testing, it was incorrectly refitted and the rack is stuck in the fuel cutoff position.

However potential fuel problems can confirmed or eliminated fairly easily by doing one of two tests.

1 - remove an injector, reconnect to HP and turn the engine over. If it sprays a half decent pattern, fuel is getting delivered; at least enough for a start.
2 - fill a small spray bottle with clean fresh diesel and mist spray that into the air intake while attempting a start. While timing will be terrible, the engine should fire and run (very roughly) while you keep misting diesel into the air intake. If so, you have a fuel delivery problem.