Starting Problems

[jimi]

Subsequent to my diesel bug problem, I have now acquired a starting problem .. no doubt due to my mechanical incontinence! This only happens if I have left the boat for more than 4 or 5 days. The engine starts initially, runs perfectly for 2 minutes and then conks out, I then have to crank it for several minutes, during which time it chucks out a lot of smoke but does'nt start and then eventually starts but with a lot of black smoke, after a minute or so it is then OK. Would I be correct in checking all the seals prior to the fuel lift pump as its liable to be a small air leak there .. or would I be barking up the wrong tree?

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[Evadne]

I would think you are on the right track, although it sounds to me more like a blockage, perhaps some diesel bug crud in the lift pump or one of the pipes? An air leak usually manifests itself every time the engine is run, I find they never cure themselves. Either way, taking various bits apart and cleaning them may well fix it, even if you never actually find out what the problem was.
I presume you are not finding water anywhere, especially in the engine filter, as that could give the same symptons (it did for me) but with rather more dire implications.

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[jimi]

When you say engine filter, do you mean fuel or oil filter?

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[Evadne]

fuel filter, the little one on the engine block.

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[norseman]

Just a thought, Is the cold start going off seems like you still have a lot off fuel still going through.

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[arran]

My knowledge of these issues is limited but I have experienced similar problems occasionally and wondered if condensation in the fuel tank could give rise to these problems?! Perhaps someone could advise.

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[Russell]

Sounds like the fuel is running back 2 the tank. This is a common problem in diesel cars, and usually means replacing the filter body which has a hand priming pump built in. I would guess that the one way valves in your lift pump have got some dirt in them which is letting the fuel run back.

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[vyv_cox]

I believe your theory to be correct. The fact that it starts initially suggests that there is nothing wrong from the injector pump to the injectors. Water in the fuel could give a problem after a few minutes of running, but it takes a lot of water to stop an engine. Worth a check by opening the primary filter, or draining it, before starting. Fuel running back to the tank doesn't often happen in boats because the tank is usually higher than the engine. Yours might be different, though. Don't forget that old favourite, a hole in the lift pump diaphragm.

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[AndrewB]

Yes, agree.

The same occured to me. But this will only happen if the fuel line runs higher anywhere along its length than the level of fuel in the tank. A quite common arrangement is to take the line out of the top of the tank. Then, the very slightest air-leak at filters or joins anywhere along the line will cause the fuel to drop back.

One of my fuel tanks has always done this, but so slowly that it takes a couple of months to drop right back. Except after a long lay-up, in practice the engine always picks up again after a slight hiccup.

(Incidentally we restore the syphon by opening the air bleed vent on the primary filter and simply blowing hard into the fuel tank's air-vent).

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[Gunfleet]

Stopping Problems

My Yanmar 1GM10 only ever conks out as I go into a lock or am turning in a tight marina. I think it has one of tcm's blinking diodes in it

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[Ivy]

Your problem is definately over fueling, This is what causes the black smoke, if it was water in the fuel ot would stop the engine instantly and if it was a lack off fuel it would be white smoke.
check to see if your cold start is going off after the engine has started (assuming you have one and not just a heater plug).
Check also that the air intake isn't getting blocked by anything.
Remember diesel's only need three things to make them work:- 1 fuel, 2 air, 3 compression.

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[BobWilliamson]

If you have not already solved the problem, it is almost certainly air in the system.
check all seals from the fuel tank are all tight and fluid tight, all the way to the lift pump and beyond to the injectors, release the bleed screw on the fuel filter operate the lift pump until fuel escapes then tighten the bleed screw whilst still pumping, then release the bleed screw on the injector pump, operate the lift pump until fuel escapes and continue to pump as you tighten the bleed screw back up. release the injector pipe union to number one injector and continue with lift pump action until fuel escapes there also, then tighten whilst continuing to pump.

The reason for the black smoke is the fact that fuel is entering the combustion chamber in spits instead of being atomised under pressure then then eventually when the engine fires up the combustion chamber is wet with non atomised fuel and thefore you get a dirty burn.........all quite simply really. with air in the system diesels dont work its a little like hydraulic action air can be compressed fluid can not................Hope this solve the problem........ if you are through, it should.......BW

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