fuel leak, can't locate source

[captran]

It started as an occasional drip, at the base of the back of the engine, just under a nut. fuel.  see picture if I can post it...leak then stopped for several weeks, then started up, but much greater volume.  one day it leaked almost 2 tablespoons in 6 hours of motoring, a drip every 50 seconds.  the next day drip started again, but after several hours more, seems to have stopped entirely, and now third day of nothing.  wiped all the surfaces, tightened all the hose fittings, but can't seem to isolate were it's coming from.  didn't see anything on the injectors, or fittings on fuel pump   not sure when we'll get another wifi spot but appreciate any ideas.   can't figure out why it would start, stop, start and stop.

[Ron Hill]

Randy : With a drip every 50 second you surely ought to be able to find that leak!
When it was leaking did you take a paper towel and touch each of the fuel connection - ie. from the lift pump on the back of the engine?, the fuel return line from the injectors? the small inline fuel filter? Start at the line from the tank to the Racor, to the elec. fuel pump, to the engine fuel filter, to the injection pump, to the injectors and then back to the tank.

If the leak has stopped take a piece of paper towel and wipe down every piece of hose and hose connection and you should be able to spot it leak.  
With your M35BC engine, you'll have to have the engine running to have that fuel system completely working.

Good Hunting, a few thoughts

[Stu Jackson]

Randy, nice to see you back after a while.  Take a deep breath.  Enjoy an evening with your family on your boat in a great location.

Then:  get SYSTEMATIC.

Step-by-step.  You have the engine manuals on board, if not on paper, then surely through this website online, if you haven't already downloaded them to your hard drive.

Follow the fuel lines and all of their connections.  Like electrical, 99% of ALL problems are related to connections.  If that approach fails, then you may have an issue related to the hoses, which Ron's ideas will help to identify.

Keep us posted, we're here to help.

In the meantime, look around - wish I had that view!  

[Jim Hardesty]

Randy,
Good advice from Stu, be systematic.  You may be able to trouble shoot in more comfort if you jumper the oil pressure switch so the fuel pump will run with the key on engine not running.
Cruising has been described as "Working on your boat in exotic places"
do what you can and enjoy
Jim

[captran]

been systematic so far, definitely a no on all the fuel line in and out connections around the pump and return/  wiped down and checked underway.  have not looked at the top of the engine underway when leaking.  when it starts up again with the leak, that will be next.  only thing different was we cut down on stanadine additive but that's it.  and when we cut back on a refuel, the leak got worse.  We'll head back over to the US in a few days but since it's not leaking now, might as well enjoy what the gulf islands have to offer.  if any other thoughts, please post and we'll check next wifi hot spot.  thanks all

[RV61]

We have been out cruising the north channel and ran into same symptoms you describe. We have the M-25 engine and found the drip was coming from bleed screw knob even when closed. Adjusted nut and so far no more leaks
for past two weeks.

[Ron Hill]

Randy : I seriously doubt that changing fuel additives had anything to do with the leak stopping - it was pure coincidence !!  

I'm sure that you are uneasy as I would be, to suddenly have a fuel leak just STOP by itself.  If it stays stopped the usual advice I can give is to check all of the hose clamps.  Don't crank (over-tighten) them down, but just check to insure they are snug.  Over- tightened hose clamps can cut into the hose and cause a leak.  Also inspect that the hose clamp is located on the hose where it should be.

Another thing to check is that your boat is getting up in age so look at the condition of the fuel lines, especially where they make a bend/curve.  My boat is 26 years old and I'm on my third set of fuel lines!! I don't wait until a fuel line fails.

A few thoughts

[captran]

The fuel leak stopped on he 31st.  we checked when we left big bay and it was still dripping.  checked it a few times enroute.  went through dodd narrows and checked and there were no drips, so not sure when it stopped. but the amount in that 7 hours of motoring was less than a quarter of what the prior days 6 hours produced.  been checking it often after putting a second plastic pan.  todays the 7th and still no sign of a leak!  checked all the hose fittings including the bleed valve, tightening every thing.  hopefully not too much.  will continue to monitor.  have another question on a different topic...wouldn't you know, my water pump (oberdorfer) started leaking a few days ago, so beat it back to Anacortes and got a new one.  easy install, works great.  but when I went to run it, now the tachometer stopped working but will post under separate question.   

[Ron Hill]

Randy : You need to wrap each fuel connection with a rolled up piece of paper towel (taped in place). 

Unless you believe that fuel leak (of your size when the engine is heated) just happen to stop - then you have the nautical spirit of the "Stop leak God " on board !??! 

A thought

[captran]

did that wrapping thing and nothing.  If (and when) it starts back up again I'll re-check everything and do it a second time.  It has to be there someplace. I seem to have a case of the "intermittents".  I was talking to someone about my newly developed tach problem and he said it sounds like a ground issue.  I hecked the back of the panel and everything is tight, but then had a thought.  The only difference between this morning and now is that we hooked to shore power, so I turned the shore power off and restarted and guess what? the tach works!  I turned on the shore power and left the motor running and the tach was fine, but when I restarted with the power on, the tach doesn't work.  Guess he next time I'm bored I'll start taking apart the AC side and check for any loose grounds.  Fortunately I have nothing but time on my hands since I am now officially retired, and still have another 5 weeks I anticipate being out.

[KINGAIR350]

This may help , it worked for me . Go to your local Advance Auto Parts and pick up a UV detector kit for Diesel comes with a pin point uv light and 1/4 oz of dye pour half in your tank start it up and motor around for a while to aggitate the dye, come back in pressurize this system and turn on your uv light youll be surprised at where your leaks will show up mine came from the case fitting on the Racor filter body (bad o-rings) and it would run down along side the mounting wall on to the bilge hoses and into the bilge, I dont use RED fuel so it made it harder but you still knew you had a leak ,bilge and aroma will let you know you have a leak using either red or jetA fuels Try it out it cost under$30.00 what ya dont use pass it along to someone else who has the same problem.
Good Luck To You !

[Ron Hill]

King : Thank You for the great tip !!!!!

I'll definitely remember that one!  Thanks again

[captran]

will find that for sure.  still, after almost three weeks or so, no fuel leak.  ever since we hit a wake before entering Dodd Narrows. 

[Ron Hill]

Randy : I'm going to take a WAG.  Check the tightness of the hose clamps, especially at the inlet & outlets to the electric fuel pump!!

Good Luck as leaks of water and or fuel - do not just go away!?!

[KINGAIR350]

How's your fuel problem ?