fuel pump heads-up

The fuel pump on my RV6/0-360 has been flucuating quit a bit lately and generally trending downward, pressurewise. Flew yesterday and happened to glance at the pressure gauge and it was at 1 lb.! Turned the elec. fuel pump on and pressure came up right away.
Decided, that's it, time for a new fuel pump (this one is brand new with 50 hrs.) Removed the cowl and started removing hoses etc. from the pump. I have Van's primer set-up which runs a small copper line from a T fitting on suction side of pump to an on-off solonoid running to cylinder heads. In the process of removing the flared nut from this fitting, the flare/sleeve assembly fell on the hanger floor. Deciding this could have well been the problem, I reflared the copper line, reattached it to the fitting and also supported it closer to the fuel pump..went out and flew, and problem solved. Pressure back up to almost 5 lbs. all the time and steady......The scarey part though, is when I thought back to when I applied elec. fuel pump. Fuel had to be spraying down onto the exhaust.....not a good situation. I left the electrical pump on for the rest of the flight, thinking I would be safer. Thought "maybe" I could detect a faint smell of fuel but wasn't real sure, so just kept the pump on.....not a good situation.
Just a heads up on something to check when you have your cowl off next time. The line going into the pump looked completely normal and I guess the best way to check something like that would be to turn on elec. pump with the cowl off and look for leaks and/or manipulate the small copper tubing at the fittings. Fly Safe!

Dave Mader
RV6/50 hrs.

Good post

Excelent post.

Anything to do with keeping us and the plane we fly safe is greatly appriciated.

I am currently flying a high wing, so no fuel pump, but now I know of a potential "GOTTCHA" to be wary of as I built the -10.

Would be a good thing for all to check at next annual, or as they do the fuel pick up mod.

Thanks.
Mike

Anytime a copper line is used between the engine and airframe, check it at least at every oil change and any other time the cowling is off. Copper tends to work harden when under vibration. I have seen many copper primer lines break right at the fitting. Stainless is a better choice for these lines. Copper is OK, IF you check them regularly.
Mel...DAR

alternative to teeing at the fuel pump

A common way to source fuel for a primer system is from a port on the gascolator (preassuming you are using one). Many of the gascolators have a 1/8 NPT port on them just for this purpose. This reduces the # of copper lines run between the engine (movable) and airframe (fixed) to one, and the one remaining line is only in use when using the primer system.

Scott

Scott,
What you say is true, but you must also remember that when that one line breaks, you introduce an induction leak causing a lean condition.
Mel...DAR

Mel said:

Scott,
What you say is true, but you must also remember that when that one line breaks, you introduce an induction leak causing a lean condition.
Mel...DAR

Click to expand...

Yes Mel you are right, though I didn't mention it.
I personally would much rather have a relatively small induction leak than fuel under pressure spraying around in the engine compartment.

As (you?) mentioned before, any hard lines installed between the engine and firewall should be inspected at every opportunity.

Scott

Mel, or anyone else:

I don't have any experience with stainless tubing, but using it between the firewall and engine sounds like a good idea. Can it be shaped by hand? What types of ends would I use: flair, solder, etc? If flair, how (I don't think the Rolo-flair is used for stainless)?

Thanks!
Jim

Hi Guys
I had the exact same thing happen to me but it broke under the nut at the flare coming off the gascolator. I made a new line (from copper) but I didn't flare it as deep as to leave some thickness on the copper flare. The broken one had been flared to tight and in the process, thinned the copper causing the break. At my next annual, I plan to change the line again but in stainless steel. I had been flying a few months when all of a sudden one day I could smell leaking fuel on a start up. It was never there before so I shut down immediately and investigated the problem. It wasn't hard to find as there was a fuel stain on the ground under the gascolator. BINGO! the primer line was loose. Back to the workshop to fix it.
I suggest anyone with ttype of set up to keep an eye on it.

Good Luck & Happy Flying
Peter
RV-9A 90491
C-GRVN