Yanmar 3GM30FW engine/fuel pump issue

[peter2407]

The saga continues ... Starting problems partly solved by changing/charging batteries plus renovating the injectors and pressure testing the cylinders - centre one is lower than it should be but the engine starts and idles and will run up to 1800 rpm ok. The problem is when going over 1800 rpm - engine throws a wobbly and cuts out. I assume that this is a fuel pump problem? Any advice as ever appreciated.

 

[charles_reed]

Probably a fuel supply issue - before blaming the pump, suggest ensuring the fuel line from pick up to pump, is completely clear (use an high-pressure air hose).
Another sign that the pump diaphragm has split is the increase in oil-level as diesel diluent runs into it.

 

[robbieg]

3GM problems-thinks to check

Problem is likely to be either fuel starvation or restriction of your exhaust gases.
Your might like to try the following in order

1. Assume the boat and prop is clean-if not clean it.
2. Spin the shaft to check it isnt' binding
2. Remove and check the exhaust elbow isn't full or carbon-this will limit revs/power
3. Check your primary and secondary filter aren't blocked-fuel starvation
4. Run clean diesel directly to your injector pump and see if she will run correctly-this should tell you if the problem is air leak/or starvation issue downstream of the injector pump.
5. If still no go run her and crack the nut at each injector fitting in turn-crude but revs should drop when you crack the nut-if they don't the injector may be at fault.
6. Check exhaust for blockages-do a temporary bypass if possible.
7. Check injection pump timing-if you haven't fiddled with it it shouldn't change but this was a problem on my engine that stopped us getting max power.


Hope this is of some help

 

[peter2407]

Thank you

Thanks for all the advice - will be back on the boat next weekend so will try the above then. Kind regards. Pete.

 

[peter2407]

The latest ....

Down the boat today to try various suggestions and found: air filter with a hole in it about 1 cm in diameter (it is a foam type filter), the air intake pointing downwards and the inside of the air filter dark with carbon. Wiping a cloth inside the air filter housing (on the engine side) it came back a little oily. Tried to take the exhaust elbow off but it was stiff and I didn't have the right tools so will try that next time. Then started the engine which kicked in fairly easily so let it run to charge the batteries and warm up. I then checked the air intake (or at least what I took to be the air filter) by putting my hand about 3 inches in front of it and got blow back as supposed to suck as I expected. So - new air filter, yes. Having tried to rev the engine past 1800 rpm, I got the same thing - engine laboured and went to kick out. Do I have an air intake blockage caused by a loose piece of foam that only becomes a problem at higher revs? Any other thoughts? Thanks as ever.

 

[Tranona]

Sounds like you have inlet valve problems. Next step a compression check.

 

[vyv_cox]

The Yanmar air filter does almost nothing and is certainly not the cause of your problem. Taking the filter out would not have the slightest effect on the engine's running. As Tranona says, maybe inlet valves or perhaps valve timing, dependent upon previous history. I would check tappet clearances first in case valves are not closing fully.

 

[robbieg]

Properly Not Airfilter

Have a poke around in the airfilter housing to see if you can find the piece of foam-however, as others have said unlikely to be your problem. I would start with the exhaust elbow (restricted exhaust) and if not that bypass the fuel lines direct to the injector to check for fuel starvation problems and then move on to valve and injector timing,compression tests etc