Universal M25 Fuel Injector Removal

Nov 26, 2019
Oday 34 Port Clinton
The #3 injector is puddling diesel fuel when the engine is running, and I am debating removing the injector myself and taking it to a diesel shop for test and possible repair. The engine is 35years old in an Oday 34, and I doubt the injectors have ever been removed. Does anyone have suggestion on how difficult this is after the fuel supply and return lines are disconnected. Their appears to be enough room to put an open end wrench on the hex head just above the manifold, but I have my concerns on how tight it may be.


Jan 29, 2018
Beneteau 411 Branford
You don't indicate where the leak is. Could be the fuel tubing coupling, the return manifold sealing washers or the copper sealing washer below the injector. I have had poor luck reusing these sealing washers. I would do it in an emergency but they really are one-time use.

It's fairly a simple task. I used to (1) loosen the fuel line at the high pressure pump (2) completely back off the tubing nut on top of the injector and rotate the tubing out of the way (3) repeat for the other cylinders (4) loosen the nuts on all three above the fuel return manifold. (5) note the aluminum sealing washers (6) remove the fuel bypass manifold and the aluminum sealing washers (7) using a metric socket on the larger hex nearest the engine block CCW to loosen. BE CAREFUL - NO CRAP in the engine hole (8) locate and remove the copper sealing washer either on the injector or still in the hole.
You will need both the aluminum sealing washers and copper see pages 33 and 58 (buy extra they are cheap). The unload lever pic shows the injector w/o the fuel tubing. When reassembling, be careful to not allow the return manifold "banjo" rings to twist with the nut.


Apr 8, 2010
Ericson Yachts Olson 34 28400 Portland OR
That model Universal was installed in a herd of Catalina boats, and the Catalina 34 site has a herd of helpful articles about the care-n-feeding thereof.
Give it a look.
Nov 26, 2019
Oday 34 Port Clinton
RitSim and FastOlson, just wanted to thank you guys. We are in the water and engine is running smooth!