New Blue Stain on Floor - Fuel Pump Problem

[0TreeLemur]

In late October I traveled to Europe for meetings and returned unwell.  For this reason I hadn't flown in awhile.  Yesterday I went to the hangar to check our J over in prep for our trip to New Mexico for Thanksgiving and I notice a new blue stain on the floor.   Investigating, it's coming from a fitting below the engine.  I remember reading somewhere that fuel coming out of this fitting means that the engine driven fuel pump is on its way to failure.  Drat.  Looks like another commercial flight...

 

[PT20J]

That is the drain for the boost pump. Fuel dripping there means an internal seal is leaking and the boost pump needs overhauling. The similar drain for the engine driven pump is a rubber hose that comes out the left cowl flap along with the crankcase breather, sniffle drain and maybe a vacuum pump outlet.

[0TreeLemur]

13 minutes ago, PT20J said:

That is the drain for the boost pump. Fuel dripping there means an internal seal is leaking and the boost pump needs overhauling. The similar drain for the engine driven pump is a rubber hose that comes out the left cowl flap along with the crankcase breather, sniffle drain and maybe a vacuum pump outlet.

Thanks Skip!  Just sitting in the hangar it is leaking a drop of fuel maybe once per 30 minutes or an hour.  It is not a bad leak.   I'm wondering if this is bad enough to prevent me from making the flight to New Mexico?

[EricJ]

I don't see any guidance in the POH or the SMM regarding leaks there.   It is an indication of a seal beginning to fail, but you may want to look in your specific POH and SMM to see if there is any guidance.  The pilot determines airworthiness, so it's really up to you, especially if the POH is silent on the topic.   I doubt you'll fall out of the sky with it just beginning to leak, and it'll drip clear of the aircraft there so shouldn't accumulate anywhere.   Definitely keep an eye on it, though.

[0TreeLemur]

We just went to the hangar and tested the boost pump.  Two times, running for 1 minute each time.   Three or four drops of fuel came out of the vent in the first 20-30 seconds then fuel stopped coming out of the vent.   It produced 27 psi of pressure.   Seems like it isn't something that would ground the airplane.

[Joshua Blackh4t]

I 'know someone' who has flown with worse. Not telling you to do so, but if it was parked outside you wouldn't notice it. But get on to a new or overhauled fuel pump.

Apparently Aeromotors in USA does them best and cheapest, but I couldn't take the downtime and had to fit a Wheldon which sounds lots nicer than the Dukes. 

[Schllc]

It can be intermittent as well. I have had them do this, but it wasn’t frequent, and it wasn’t much. 

[0TreeLemur]

2 hours ago, Joshua Blackh4t said:

I 'know someone' who has flown with worse. Not telling you to do so, but if it was parked outside you wouldn't notice it. But get on to a new or overhauled fuel pump.

Apparently Aeromotors in USA does them best and cheapest, but I couldn't take the downtime and had to fit a Wheldon which sounds lots nicer than the Dukes. 

The one that is on there is a Weldon according to the logs.

[DCarlton]

I’m not a mechanic but I had a similar leak with a very similar stain on the ground.  It wasn’t dripping from inside the fitting, it was running down my fitting.  It’s hard to tell the difference with a drip.  Based on my experience, I would suggest removing the access panel and looking more closely before you fly.  My plane is an F though and again I’m no expert.  See the link below for the source of my leak.  In my case it was not the pump.  
 

 

[Ragsf15e]

13 hours ago, DCarlton said:

I’m not a mechanic but I had a similar leak with a very similar stain on the ground.  It wasn’t dripping from inside the fitting, it was running down my fitting.  It’s hard to tell the difference with a drip.  Based on my experience, I would suggest removing the access panel and looking more closely before you fly.  My plane is an F though and again I’m no expert.  See the link below for the source of my leak.  In my case it was not the pump.  
 

 

Agree it’s important to see what’s happening in there before making a decision, but I think his is the boost pump, not the selector.  The drain holes for them are close together though, so important to clearly identify which one.

[Fritz1]

Most likely boost pump shaft o ring, a lot of overhaulers have them in stock, my boost pump started leaking a bit one day last summer and seized at the next start the next day, fortunately in front of my own hangar, no start, my A&P said these pumps are good for about 2000h, mine had 1850h, took about 3h to replace

[0TreeLemur]

I took that panel off today and gave the boost pump a good looking over.  Everything appears fine.   Fittings are good, no external leaks. 

Since we tested it Sunday it hasn't leaked any more fuel.   Went for a test flight today to top off with cheap ($4.30) fuel, and when I returned it was not leaking.   I'm thinking that since I didn't fly for 5 weeks, maybe the seal dried out enough to let a little leak out.  Anyway, I don't see this as something that grounds the airplane.  The pump works fine (27 psi) and has stopped leaking out of its vent.  Thanks everyone for sharing your thoughts.  This board is a great resource.

[0TreeLemur]

On 11/25/2024 at 12:26 PM, Ragsf15e said:

Agree it’s important to see what’s happening in there before making a decision, but I think his is the boost pump, not the selector.  The drain holes for them are close together though, so important to clearly identify which one.

On our J the gascolator drain hole is about 2 ft aft of the boost pump drain hole, which is almost 2 ft aft of the engine driven fuel pump vent hose .