Sign in to follow this  
Followers 0

Rotax 582 power loss diagnosis

22 posts in this topic

Posted

So went out flying the other day. Flew about an hour and then stopped at a friends private strip. Sat around and talked for about 30-45 minutes and then took off again. On the departure I again warmed up for several minutes at 2800 rpm to get the water temperature to 140 deg F. Took of and turned toward my home airport and climbed to about 1500 agl. After leveling off and about 2-1/2 to 3 miles from my buddies place the engine stopped. It was not immediately after leveling off. Acted like no fuel, not a seize or anything like that. Set up glide an turn back toward my friends place and while simultaneously hit the starter and the engine cranked but did not start. while in the glide I tried again and no luck. I then gave it 2 shots of prime (regular aircraft primer like in a Cessna or Piper) and the engine started and ran for a few seconds but quit again. 3 shots next time and it ran a bit longer.  Did this again and the engine ran and ran fine. Continued back to my friends strip and landed uneventfully.  On the ground we pulled the exhaust to check the pistons and they look perfect. No scoring whatsoever.  I had about 1/4 tanks of fuel (26 gallon wing tanks) but went ahead and added more. After buttoning up I started it, did another of my standard 2800 rpm to 140 deg F warm ups and took  off. I stayed directly over his airport for about 15 minutes and didn't have a problem so continued back home and again had no issue. Temperature on the ground was about 75 deg F.  I did not notice the gauge readings at the exact time of the power loss but I had looked at the gauges about 15 to 30 seconds before the engine quit and everything was good.I have a fuel pressure gauge and it was also showing good  at about 5-5.5 psi at that time. On the flight home I was watching the gauges like a hawk and they always stayed in normal parameters. The fuel hoses are all fire-sleeved in the engine compartment and the hoses were replaced when I bought the airplane last fall.  Kind of at a loss for why this burp happened. I am pretty convinced it is fuel related because of the having to prime to get it going again, but I had fuel and had not been in a descent that could have un-ported the main tanks.  I do have a round aluminum header tank behind the seats.  

Any ideas?

Share this post


Link to post
Share on other sites

Posted

Can you draw your fuel system exactly and post? Does it have two tanks? Ar there any filters? If so, where are they physically located? Gascolator other than header tank? Is there an atmospheric vent from the header tank? Any filters right at the carbs? Are there any siphons (where tubing leaves a tank or tanks and goes back uphill before it enters the header tank)? Could you have vapor locked? Seems unlikely because you flew much longer than the time fuel in the bowls would have kept the plane flying.

Share this post


Link to post
Share on other sites

Posted

Yeah it is puzzling.  

There are 2 wing tanks vented at the caps with forward facing vents like normal. The rear inboard outlets from these tanks run to the side inlets on the round aluminum header tank located at the at the back of the baggage sack. The top vent of the header tank runs to a forward high fitting on the right wing tank.  All of these lines are routed downhill. I didn't look to see if the hoses had move possibly creating a dip in any line but when I installed I made sure there were none. So unless something moved there should not be any dips in those tubes.  

From the header tank the fuel line runs forward along the floor on the right side of the fuselage and then up to the shutoff valve. Valve to gascolator. Gascolator to fuel pump. Fuel pump to carbs. No other fuel filter besides the screen in the gascolator. Last fall when I bough the airplane I made sure the gascolator screen was the finer one. I think about 70 microns or so.  Figured that if something got through that it would go through the carbs.  

When I flew back i didn't have time to poke around the airplane much. Pretty much had to put it in the hangar and head home. Hope to get back there tomorrow to check everything out.

Share this post


Link to post
Share on other sites

Posted

Here is a crude drawing of the fuel system.

fuel system.png

Share this post


Link to post
Share on other sites

Posted

Possibly a fuel pump pulse line collapse temperature related.  or maybe the pump pulse diaphragm has a crack in it creating an intermittent leak? 

Share this post


Link to post
Share on other sites

Posted

I'd replace the pulse pump.  I've had em be intermittent with those same symptoms.  Also maybe add an electric boost pump to double down on redundancy. 

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

Very clear explanation and drawing. Looks well implemented to me with the possible exception of the header tank vent. With two tanks feeding the top of the header tank, there is no need for that vent and there are some unlikely scenarios where that vent can result in reduced head pressure. Some who install those header vents place a shutoff valve in the line so that once all the air is out of the header it is shut off. However I do not think that is the source of the problem. Do you have a primer setup? If so, how is it installed?

I agree with the other posters that since you don't have a boost pump, it might be a good idea to replace or rebuild the fuel pump and replace the pulse line just out of an abundance of caution.

Edited by ChrisBolkan

Share this post


Link to post
Share on other sites

Posted


had that happen twice.  Both times the back up electric pump saved my ass.  running along fat dumb and happy then silence.  Deafening silence.  hit the boost pump and primer and fired right back up.  Caught it a couple times when the fuel flow meter started dropping and hit the boost pump and things went back to normal.  Were you running with both tanks on? 

Share this post


Link to post
Share on other sites

Posted (edited)

Thanks guys.  Yep.  Both tanks were on. I bought valves to install in the tank lines, but haven't installed them yet. so I only have a shutoff after the header tank  right now.

Didn't draw the primer setup, but it uses a regular aircraft type primer like a Cessna or Piper would have . The primer draws fuel from the outlet of the only shutoff valve via a Tee installed there. The outlet of the primer goes to the primer fitting on the carbs.

Sounds like its all adding up to a bum fuel pump. I'll get one ordered.  

For backup electric pumps, what are you guys running and how have you plumbed them.  I'm definitely going to do something and I'm thinking one of the interrupter type pumps is the way to go because you can get them where they don't restrict flow when not turned on.  Any help on what you guys are running is appreciated.

Thanks again.

Edited by 109jb

Share this post


Link to post
Share on other sites

Posted

I had a facet 4 psi on my 582.It was plumbed in line before the pulse pump and gave no trouble. Use a genuine facet not a copy  I used a knockoff on my 912, this one failed internally after a very short time. It was making the right noises but not pumping.

Share this post


Link to post
Share on other sites

Posted

The Facet 40105 is the go to standard for 2 stroke.

Share this post


Link to post
Share on other sites

Posted

Thanks guys.  I have a pulse pump rebuild kit and a Facet 40105 on order. 

I found this page http://www.challengers101.com/FuelSys.html that shows the different options for fuel systems. I'm thinking to just put it in-line after the gascolator and before the Mikuni pump. I wonder though if the parallel system would be better because it would be safer for running the electric pump for critical phases like takeoff and landing since it would not add to the pressure which could overcome the float needle and flood the engine. Not sure what the float needle on the 582 can take. How have you guys plumbed them up and do you use them for takeoff and landing?

 

Share this post


Link to post
Share on other sites

Posted

You cannot push through some pulse pumps so check on that.

My setup on the carbed yamaha is parralel with a check valve to prevent backflow. 

Works well but when they are both pumping I see about 6psi which my carbs are holding back fine but I'm not sure what the limit is on the Bing. 

Share this post


Link to post
Share on other sites

Posted

FWIW here's a pic and description of how I did mine:

 

Screenshot_2020-06-04-21-42-20.png

2018-10-31_19.09.55.jpg.5f244ccdb97e7aacf00c59a5e67dbc93.jpg

Share this post


Link to post
Share on other sites

Posted

Yeah. It is more work to hook up but I think I'm going to go with the parallel setup.  The pressures should not add in parallel and should be the higher of the 2 pumps.

Share this post


Link to post
Share on other sites

Posted

I have no idea if one approach is better than another as both have merits, but the way I have done my systems is with the Facet in series, and placed in the center console just after the header tank. My reasoning being that the header filters out particles and crap large enough to screw up the pump by low flow velocity and settling. I place the facet pump right after the header tank in the circuit where it is at the lowest point in the system, and has the greatest opportunity to pick up fuel at the highest head pressure and "push" through the most potential obstructions down stream. I pretty much never turn on the Facet except to start the plane, and then only because I have the starter switch wired electrically downstream of the boost pump breaker switch. So, I cannot start the engine without the boost pump being on. Once the engine starts, boost pump is typically turned off and I never really use it during flight. Occasionally if I am taking off from a scary strip I will leave the boost pump on but not during normal operations. Fuel flows right through the facet when off.

Share this post


Link to post
Share on other sites

Posted

Yamma-Fox, I may need to re-think my system if as you say the pulse pump does not let fuel by in either direction. I just now read that in your clip above from a previous post. I have taken one apart before and thought the one way valves were is series but flowed the same direction.  Gonna have to check that out. Thanks for the heads up.

Share this post


Link to post
Share on other sites

Posted

I'd replace the pulse pump.  I've had em be intermittent with those same symptoms.  Also maybe add an electric boost pump to double down on redundancy. 

The additional Facet electric pump at the firewall to pressurize the whole engine system is a great idea. I bet you saved the flight by pumping the prime to fill the lines after they were emptied, you were the boost pump. Smart thinking, especially while your heart is in your mouth!.

Share this post


Link to post
Share on other sites

Posted

Yamma-Fox, I may need to re-think my system if as you say the pulse pump does not let fuel by in either direction. I just now read that in your clip above from a previous post. I have taken one apart before and thought the one way valves were is series but flowed the same direction.  Gonna have to check that out. Thanks for the heads up.

The ram air tubes on the Avid Flyer fuel caps came about because one of the owners of Avid crash landed in the mountains out west on a flight to Oshkosh after a fuel pump failed on his 582 powered engine.  It was determined that the 582 would run if the fuel pump quit if there was the added pressure supplied from the ram air tubes to the fuel tanks.  I think there was a service bulletin regarding this.  The Avid is plumed somewhat different for venting from a Kitfox, and that may make a difference between how the two aircraft would act if the pump quit.  I do know I fly my Jabiru powered Avid MK IV all the time with just gravity feed, except for takeoff when I use an electric fuel pump.  I had done tests though at altitude where I ran at full throttle with just gravity feed for several minutes, and the engine never stumbled.  EGTs didn't go up at all even, which would have maybe been the first sigh of running shy of fuel flow.  YMMV.  JImChuk

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I'd replace the pulse pump.  I've had em be intermittent with those same symptoms.  Also maybe add an electric boost pump to double down on redundancy. 

The additional Facet electric pump at the firewall to pressurize the whole engine system is a great idea. I bet you saved the flight by pumping the prime to fill the lines after they were emptied, you were the boost pump. Smart thinking, especially while your heart is in your mouth!.

Thanks. It was a surprisingly calm event.  I'm sure that is because I was over miles of farm fields that had just been planted so consequently I had miles of pretty smooth dirt to land on if needed. I guess that's one benefit of living in flat Illinois. I actually glided for what seemed like a while before I had the thought to use the primer. Sure was glad this airplane had the primer rather than just a choke.

2 people like this

Share this post


Link to post
Share on other sites

Posted

I realized that I never updated on this.  It turned out that the pump was bad. I ordered a rebuild kit and replaced everything even though none of the old parts looked bad in any way. I know that it was the pump however because when I got it done I found that the fuel pressures were very steady on the gauge. Before I rebuilt it I always had some fluctuation on the gauge that I assumed was normal. With the new parts in the pump the gauge reading at cruise is very steady. It varies with RPM, but once an engine speed is selected the fuel pressure is steady. The pulse pump will be on an every year rebuild cycle since it is only $15 for a genuine Mikuni rebuild kit.

3 people like this

Share this post


Link to post
Share on other sites

Posted

Can I strongly suggest the electric backup pump mentioned above? You can switch it on for landing and takeoff, put it off in cruise except when things get too quiet, when it can get you started again.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0