I've got a real head scratcher that I'm hoping someone can shed some light on. I went to the marina on Sunday and as I walked up the pier towards my boat, I noticed a stain streaking down the hull from the bilge outflow port. I checked the bilge and found it contained a substantial amount of diesel fuel. I checked the engine compartment and found the forward half of the oil absorbent mat on the floor beneath the engine was soaked with fuel while the back half was not, but, I could not see a leak anywhere. I then ran the engine, but still could not locate the source of the leak. I cleaned under the engine, replaced the mats and ran the engine for 5 minutes and still could not find any evidence of a leak. I checked again yesterday and the new mat is still spotless. We ran the engine the previous weekend for a few hours bit did not notice any problems at that time. Now, however, I am completely flummoxed as that fuel had to come from somewhere. I'll take her out a bit this weekend to run the engine under load to see if that makes a difference, although I don't know why it would. Any thoughts?
Fuel Leak
- Thread starter rkssail
- Start date
Check to make sure the tank vent is free. Spiders like to get in there and plug the little screen. My fuel return line from the injectors to the tank cracked last year and would drip/drool but only when the engine was running. That is the line that goes to the aft end of the tank. I have had the banjo fittings on the fuel pump outlet leak intermittently when the engine is running. Usually the dreaded banjo connectors and copper washers. These drip leaks are really tough to locate.
You could remove any pads from underneath the engine and place a dry piece of cardboard underneath. Run the engine under load and check the cardboard to see if you can find where a drip may have occurred. Take your hand and feel of the undersides of any and all filters. If the leak is a situation where it drips, then you will probably have to find it by feel. Feel the bottom of the fuel pump with your hand also. If you find a spot that you think is a leak, then dry the spot with a cloth and retest the spot to confirm your findings.
RE: Fuel leak...
From what you describe as to leakage area under the engine, I would suspect the fuel filter lock ring O-ring or the plastic washer under one of the bleed screws on top of the filter being cracked as the possible source.
Use a face tissue to gently wipe under each banjo fitting (as Kloudie pointed out) one at a time, and the bottom side of the fuel filter. Also, wipe around the bleed screw on the top of the high pressure pump. Lastly, check each rubber fuel hose end for cracking.
Because the fuel leak appeared at the front of the engine and the pad was soaked, it would seem that the leak was under pressure, putting it probably after the lift pump. Try shutting off the fuel line valve at the tank exit when you leave the boat to see if that helps. Could also be a vacuum causing a siphoning to the leak point.
Experience is the best teacher...
From what you describe as to leakage area under the engine, I would suspect the fuel filter lock ring O-ring or the plastic washer under one of the bleed screws on top of the filter being cracked as the possible source.
Use a face tissue to gently wipe under each banjo fitting (as Kloudie pointed out) one at a time, and the bottom side of the fuel filter. Also, wipe around the bleed screw on the top of the high pressure pump. Lastly, check each rubber fuel hose end for cracking.
Because the fuel leak appeared at the front of the engine and the pad was soaked, it would seem that the leak was under pressure, putting it probably after the lift pump. Try shutting off the fuel line valve at the tank exit when you leave the boat to see if that helps. Could also be a vacuum causing a siphoning to the leak point.
Experience is the best teacher...
What has me baffled is that the fuel leak seems to have been a one time event. I've had her out and have run the engine for a couple of hours since my original post and there has been no additional leaking. The new pads that I placed below the engine are spotless. Don't get me wrong, I am certainly glad that it is no longer leaking, but I would sure feel better about it if I knew where that fuel came from originally.