ST3 Fuel leaking from injector pump identification help

[Dash]

Hi,

I understand there are threads around with great info in about this problem and I have followed them for most of the way through but I'm looking for advice on an issue.

I have an ST3 based gen set, Unit was stanby use and conditionn wise inside looks brand new but when I recived it the sump was moslty thind oil with diesel so I knew there was an issue from there, Following the info around all the low pressure side was checked and nothing leaked, from there I checked the leak off pipes and injector lines and all was good there including when running also.

I losend the three joins above the injector pumps and all three are getting fuel though one seemed a tad dryer but I can here to creek from the injectors during turnover. I think if I remove the pipes I should see if they all work unless this leak only happens when the pump is under pressure, I placed the decompression on with the crankcase door off and turned the unit over a handfull of times with fuel enabled in hopes id see something leaking but I have strugged to see anything, I can hear the injectors fire and nothing really gets wet or drips in a noticable way.

When running I can watch the fuel level drop over 30 - 40 seconds with something like 100ml used in that space so I know one of them must be leaking on the underside at running speed but it seems to run smooth with no smoke or stutter and the leak only seems to happen when running so Id think its the injector pumps now given I didnt find anything at all the other joints, I understand this is on the rare side given it seems the engine hasnt done many hours.

How can I go about find the right one, I'm a tad lost and Id rather not have to take all three out if I can avoid it, though needs must if thats the case, it'll be a learning experience

Any pointers or help would be appreacited

Thanks, Dash

[KC7NOA]

hi ..
you could try getting all the copper seals replaced .. or pull them all and soften them yourself ... polish flat on glass,
there might be a crack in one of them from being over tightened ...
or a crack in one of the fuel lines ...

you can also get a fuel pump and pressurize teh fuel and let it run for a while ( i mean teh electric fuel pump -- not the motor )... it should flow through teh return

as an idea i just had .. when electric pump is running ... tie strips of paper towel in various places, looking for a slow collection of diesel if you cant see the leak

[Dash]

Hi

Thanks, This leak isnt from a craked pipe or bad seal from what I can tell after looking arond, The fuel loss only happens when running and I have watched all pipes during that test, its chewing near 100ml in 30 - 40 seconds and not from anything on the low pressure side or the high side from the top of the injector pump or at the injector itself.

Given the loss is when its running and there is nothing from the leak off pipes or the injector pipes it only leaves the injector pumps, I'll have another attempt at trying to see if from the crankcase, it must be one of the pumps

[KC7NOA]

if its one of the pumps .. you might need to replace it .. or get a replacement piston .. i dont remember seeing any seals when i took mine apart to clean the shalacked ( is that a word ? ) diesel that was gummed up in mine ( rust too ) ...

I would hope that the piston is softer than the body of teh pump ... i dont know.

[Dash]

Thanks, Would there be a way to test to see what one it could be in situe ? I have tried cranking over with the starter but I dont see any noticable leak ; Id guess it ramps up fast on full speed.

Do you have any tips outside the manaul when it comes to taking these out, My only concern is not to mess up the fuel settings or the linkages between the three pumps.

My other option would be to remove all three together if I can and take them to a specalist local to me.

[KC7NOA]

i dont know of any videos to properly take them out ...


all i know is that you dont want to bend the rack any ...
the cotter pins that are bent around to hold the interlink pins will most likely break so you should source them -- i used pins out of a mix set from Orilleys ....

i dont have a way to test the pump at my place ... iv seen a home made stup on you tube , the guy used a press and some fittings and a pressure gauge to check the injector trigger pressure .. but i bet the same setup can be used to check for leakage -- doing a leak down test .. just pressuize and wait a bit fto see if the pressure drops durring a set time -- and i have no idea what time duration that would be but i would guess two minuets ....