582 fuel pump help

[beeryboats]

I'm trying to breath life back into a model IV that was left to rot for 10 years. I'm making progress, but little stuff is starting to slow me down. Like this fuel pump. From what I've read the builder installed it wrong, vertically, so now I have to make a horizontal mount. But I want to replace or rebuild it first. I've found two, both overseas! I don't see it in the LEAF catalog or the Kitfox parts PDF. Any ideas what to do?
Thanks,
Jay

[avidflyer]

It is a mikuni pump which is used on snowmobiles. Get the pump parts through a snowmobile parts supplier maybe. Just be sure to put them back in the right order. Jim Chuk

[Av8r_Sed]

Jay,
Don't get yourself too tied up in fixing what may not be broken. The mounting of the fuel pump you have is straight out of the original build manual and will work fine. Yes, a better mounting may be horizontal, but you'll find it will work without trouble for you as-is.

Spend $15 for a rebuild kit and move on. Here's a link:

http://store.leadingedgeairfoils.com/advanced_search_result.php?sessId=19C94B92D7E7FFCC F1A7CD8292AD94CB&keywords=Rebuild+Kit+for+Mikuni+Dual+Fu&x=6&y=11&search_in_description=1

[jrthomas]

So mounting it vertical is wrong? I've never heard that one. I ran one for 15 years vertical and I don't think I've ever seen one mounted on its side. I don't think it knows the difference since it only has a diaphragm that works off of crank case pulses. I'd buy a new one and put it back where is was. Make sure you use a good quality pulse line. A too soft pulse line will absorb the crank case pulses. James Thomas

[Av8r_Sed]

There's a tiny weep hole to drain any condensate or leakage which in theory should be mounted face down, but like James, I've never ever had an issue with the vertical mounting.

[beeryboats]

Make sure you use a good quality pulse line. A too soft pulse line will absorb the crank case pulses. James Thomas[/quote]

I wonder if a guy should use stainless steel braid line?

[Av8r_Sed]

Nah, not really necessary. Just order up some pulse line when you order the rebuild kit.

[jrthomas]

No need for anything fancy for a pulse line. Just good quality fuel line will work fine. Ultralight folks use a lot of clear Tygon fuel line. It's ok but it's only good for about a year. It's pretty soft so it's not a good idea to use it as pulse line. I say this because I have seen it used as pulse line. Tygon is ok where the engine is out in the open but I'd use the good stuff and a fire sleeve in anything with an enclosed engine. James Thomas

[Dusty]

The pump must be mounted higher than the crankcase nipple or it may fill with oil.The weep hole is to help reduce this possibility

[Olle1975]

So mounting it vertical is wrong? I've never heard that one.

Hi!

Have a look at your Installation Manual page 15. The drain hole has to mount towards the bottom, ergo horizontal installation.

Regards

Olaf

[KFfan]

Ollie, I agree with you.
The manual however uses the word "should" leaving the final mounting orientation to the installer.

The one on my model 2 is mounted vertically and rather high with respect to the fuel tank. I plan on remounting it as well as adding an auxiliary electric pump.

[t j]

However you mount it try to keep the pulse line as short as possible. The Rotax manual says no longer than 20 inches. Less than 12 is best.

My Kitfox builder's manual has the pump mounted horizontally high on the firewall. The problem is on the 503 the pulse port is near the lower front of the engine so the shortest I could make the pulse line was 21 inches.

It seemed to work fine during the static engine break in but on the first flight of about 30 minutes the weep hole spewed oil all over the firewall.

I tried everything to fix it. Asked questions on several forums too. The overwhelming response was no one had ever had anything leak from that weep hole and that my pup definitely had a ruptured diaphragm.

I could not find any holes in the diaphragm so ordered a new pump from CPS. That new pump DID NOT have the weep hole. Mike Stratman at CPS was adamant in his Tech articles that the pump MUST have the weep hole. Go figure. I returned the pump to CPS and they sent one with the weep hole.

That new pump did the same thing...spewed oil all over the firewall during flight.

I rigged a catch tube under the pump and went and flew for an hour to see how much oil it was dripping. It was about an ounce and a half.

Then called CPS to ask some questions. He was speaking from a script and WOULD NOT answer my questions.

I tried asking on the forums some more and got the same old answers. "Your fuel pump diaphragm is ruptured" or "Your engine has excessive blow by"

Then......a guy on the Matronics Kolb List...that's a good place to ask 2 stroke questions...says "Your pulse line is too long".

I mounted the pump horizontally under the carbs so the pulse line was about 8 inches long. That cured the problem. Not one drip out the weep hole sense.

[KFfan]

Thanks for passing along your insight/experience tj!