fuel leak at injector pump

[glenn maerki]

1989 Cummins 6BTA5.9M 250 HP. CPL 953. twin engine boat. port engine

I have a fuel leak somewhere on the injection pump/injector line connections. ran a shakedown cruise and everything seemed to be running well. max RPM on both engines…2675 RPM. no smoke, nothing out of the ordinary. Both engines ran about 165 degrees ( I have Tony Athens 165 deg thermostats).

got back to the dock and went down to the engine room and found diesel all around the outboard side of the port engine. Got a mirror and a flashlight and found a diesel drip at idle that looked like it was coming from around the annulus of the pump where the pickups are for the injector lines. Is very difficult to find the source of the leak. I pulled the pump, had it rebuilt, reinstalled it and just ran the engine only to find it still leaking. The fuel drip ends up dropping from the bottom injection line fitting. Any ideas/suggestions/guesses are welcome.

To recap, the engine runs perfectly. no starting issues, I get max RPMS when I run and no other symptoms other than diesel fuel everywhere. When I’m running hard it is spraying around the port side of the engine. HELP!

thanks

Glenn

Topic

[glenn maerki]

the saga continues

thought i had the leak problem solved but running for about an hour with an oil absorbent pad under the pump I would estimate maybe a half an ounce or so stain on the absorbent pad. So I pulled the pump again and replaced all the banjo bolts and crush washers. Just took another ride and still leaking but I have no idea where from. On top of that, I now have an idle roll of 100-125 RPM at low idle and higher idle(1300 RPM). This BTW is the same engine I’m having temperature creep on. So 2 more questions:

1. what would cause the idle roll?
2. suggestions on how to deal with the inj. pump leak. I’m out of ideas.the leak is small enough where you cant find the source but its still a fuel leak.

thanks in advance for your input

[donald roth]

Sometimes you just have to tighten the snot out of the offending fittings, and you may need to put some custom bends in your end wrenches to accomplish that.

[glenn maerki]

injection pump leak

there are crush washers on the banjo bolt. all were replaced when the pump was rebuilt

[Philip]

If it were me i would remove the banjo bolt. It looks like there is a washer top and bottom of the connection. I would get all super clean and then coat both sides of the washers with Rectorseal and get it all nice and tight.

If that doesn’t work you might try and source new washers from a local fuel injection repair shop.

Let us know…

Phil

[glenn maerki]

found the source

I tried to delete my previous post but apparently cannot do that. Anyway, I used paper towels to isolate and then recorded short video of the location on engine start. Would like to try to fix without removing the pump but not sure I can do that……

[glenn maerki]

short video

used a GoPro to get a video of the leak. the drip you see to the right in the video is coming off the tube at the 6 O’clock position (bottom of the pump). the drip on the left side is coming off the port at the 8 O’clock position. Hard to get a video of the port at 10 o’clock because of restricted access. not sure if the leak on the left side (8 o’clock position) on the pump actually starts higher….maybe the 10 o’clock port. I have a lot of video and i dont see anything from above the pump (i.e. fuel supply lines) so it must be the pump…???

any ideas?

[Francis Valerio]

Try to clean the area, maybe with compressed air (I know that may be difficult at the dock), do your best to DRY the entire area. Let it sit for 20 or 30 minutes not running and then use tissues to probe the area where you can not see. Maybe she will drip by that point and you can get a better idea EXACTLY where the leak is coming from.
I understand completely about being able to see in areas that are impossible to see….lol.

Maybe manually prime the lift pump handle to build some pressure if she did not leak at this point.

If she still does not drip then run her for a bit to see and repeat above.

I am not very familiar with your pump but they all work under the same principle.

you need to start with everything as dry as you can get it.

Brake cleaner maybe but be environmentally friendly…

Let us know

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Tony Athens

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