Help...Engine Issues

I have over 250 hrs in my RV6A with a TMXO 360 and a C/S prop...here's the situation. Yesterday i was out performing a few loops and i had the engine stall out on me twice, initially i thought "ok maybe i went a little negative and starved the engine of fuel" although i entered the maneuver at 140 and pulled 3G's like several uneventful times before. Today i took her out again and made an approximately 2-2.5G climbing left hand turn at about a 60 degree bank with the fuel selector on the right tank and it coughed out again!!! now i have grounded the RV until further notice...has anyone experienced anything like this before? I fly my RV very regularly and in a similar fashion to the maneuvers described above and it has never sputtered once. Oil pressure is good, fuel pressure is good, mags check out, CHT and EGT are normal. Any ideas would be great, thank you in advance, Jeff

fuel pickup issue?

loose fitting on the fuel pickup line inside the tank? perhaps sucking air at certain fuel levels and angles of pitch/bank?

Fuel pump going bad? Fuel filter clogged? Partially clogged vent? I'd go with stuff that is most likely to occur with normal wear and tear.

I'd also pull the carb and go through it.

Thanks for all the ideas...im on my way to the airport shortly and will start with the obvious and go from there...i hope i can figure it out, i don't ever want to bring my RV in dead stick...she has the glide ratio of a thousand pound rock lol

It could be vapor lock. The pump on the engine has to pull fuel "higher" when pulling g's. Meaning, it needs a bit more vacuum at the inlet of the pump to suck the fuel than during 1 g flight. Try it with the boost pump on.

I tried everything i could think of but could not get her to spit or sputter again, i did go through and check both tanks and gascolator etc but only found a small amount of debris in the filter...i don't believe enough to make any sort of difference. i guess ill have to wait till it acts up again...thanks for all the help guys!

jeffpohl4 said:

i guess ill have to wait till it acts up again...thanks for all the help guys!

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What if the next time it acts up is at 200 feet on climbout over a crowded neighborhood?

I would take a serious look at everything and maybe even have a professional take a complete look at it before I just continued with business as usual.

Just my opinion. Worth what you paid for it.

I'd look at the carb. The float in particular.

Fuel Boost Pump???

Did you forget to switch the fuel boost pump on prior to the aerobatics?

Carb float

I agree... I'd be suspecious of the float. If it has a leak and partially "sunk", when pulling G's, it could pull the float down into the bowl, thus the needle valve out and cause a momentary flooded condition that clears up when the G's go away.

The Tempest/Marvel Schebler blue epoxy "unsinkable" floats are about $100 from spruce. Add a few more bucks for the necessary gaskets, retainer clips, etc to swap it out and it's not too much money for some peace of mind.

Here's their promotional video for them: http://www.youtube.com/watch?v=cG639ESY9-4