Today's Message Index:
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1. 02:29 PM - Re: 912 ULS Fuel Pressure (Carl)
2. 02:42 PM - Re: Vapor lock 914 (FLYaDIVE)
3. 02:49 PM - Re: 582 grey head ignition (Bart Rond)
Message 1
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| Subject: | Re: 912 ULS Fuel Pressure |
HI Stan
One year ago I had the same symptoms that you had. I believe this was
caused by the fact that the electric pump has a slightly higher pressure
than the engine pump and this causes the engine pump to stop pumping
while the electric pump is "on." This stagnation of fuel in the engine
pump during TO/Climb cause that fuel to vaporize and a momentary loss of
pressure when the electric pump is turned "OFF".
I've moved my gascolator, filter and boost pump to the rear compartment
and firesleeved all the lines. I also ran a return line to my right wing
tank. Seam to have helped some but I still see the pressure drop and the
occasional warning light when I turn the boost pump "OFF". Never
affected the engine but always ready to reselect to boost pump.
After shutdown on a hot day burning auto fuel, put an ear close to the
engine pump; bet you will hear the fuel boiling.
Carl
----- Original Message -----
From: Stan Tew
To: rotaxengines-list@matronics.com
Sent: Monday, July 13, 2015 6:47 PM
Subject: RotaxEngines-List: 912 ULS Fuel Pressure
My 912 ULS mounted in my Rans S7-S has 438 hr. I replaced the old
style mechanical pump as recommended by Rotax. I have an electric fuel
pump and fuel pressure gauge. I usually take off with the electric pump
running in addition to the mechanical pump. When I level off to cruise I
turn off the electric pump. My pressure usually is about 4.5 psi. Last
week I was flying and noticed the EIS warning light and it identified my
fuel pressure to be about 0.9 psi. I quickly turned on the electric
pump. The pressure went to about 3.5 psi. I flew back and landed without
incident. The engine never faltered.
Any suggestion on how to test the mechanical pump? Any suggestion on
what the problem might be? I have not had opportunity to remove the cowl
to make any visual checks.
Stan Tew
N29TD
Message 2
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| Subject: | Re: Vapor lock 914 |
Peter,
That is not vapor lock!
That is IMPROPER part insulation.
1- Two boost pumps are not required.
2- The boost pump should be after the fuel selector.
3- What size lines are being used?
4- Gascolators... I hate them! They must be located at the very lowest
point in the fuel system. They are a pain to maintain. Their are AD's
concerning the safety wire procedure and the drain valve. They give a
false sense of security. And, they don't work very well.
My guess is you are flooding the carb. Not starving it.
Do you have a fuel flow gauge? Check what the MAX fuel flow is from the
engine manufacturer and comparing it to what you are seeing.
Since you are both a gravity feed and a boost pump feed flooding is more
than likely your issue. So, to answer your question about a return line
back to the tank! YES, that would be my suggestion also.
Next question: What FACET pump do you have? Some of their pumps stop fuel
flow or have a high resistance to fuel flow once the pump is turned off.
Next question: Many builders think bigger and more is better. What fuel
flow rate does your pump supply?
Next question: Did the designer say boost pump?
Prove to yourself that it is vapor lock. Bet you can't! IF you think it
is vapor lock use AvGas and wrap aluminum foil crumpled around the hoses.
You can also build a "COOL CAN"... A coil of copper tubing in a metal
coffee can where you pack in Dry Ice. This will definitely eliminate vapor
lock and increase the SG of the fuel and increase the HP.
But, my money is still on flooding.
Barry
On Monday, July 20, 2015, Peter Thomson <peterlthomson@gmail.com> wrote:
> Friend has been having problems with "vapor lock" particularly at take off
> power.
>
> Aircraft is Pelican, high wing, L and R wing tanks feeding through a
> L-Both-R-OFF selector to a gascolator, then through two Facet pumps in
> series to carburetors, with airbox. Return line is T-eed back to the
> gascolator. Most lines fire-sleeved.
>
> Could the problem be fixed by taking the fuel return back to a wing tank ?
>
>
> *
>
>
> *
>
>
--
Sent from Gmail Mobile
Message 3
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| Subject: | Re: 582 grey head ignition |
Hi Richard and Guy,
Thanks for the tips, you were both right! So far I was able to track it down
to either the generator or the wires to ignition box 2. Sunday we switched o
ut the ign.box for a spare one and the problem stayed the same. I also measu
red the coils in the generator, the kill switches and the wires that connect
them, no problem there. When I interchanged the connectors of the wires to t
he kill switches, the problem moved to the other switch.
Today I mounted new connectors in the white and green wire between the gener
ator and the e-box, no change, the engine still stopped with ign2 ON and ign
1 OFF. Not all the time tough, but after a few minutes of taxiing!!
Then I was sure I had it fixed, when I cut the white and green wire close to
the generator housing and connected new wires instead. The engine kept runn
ing all the time on both ignitions!!
So I cut the engine to put insulation on all connections and secure all wire
s with tie-ripps, and then the downer occurred: the engine only ran on ign.1
and ign.2 did NOT function anymore!
Enough to go absolutely insane....
To be continued!
Bart
Verstuurd vanaf mijn iPad
> Op 19 jul. 2015 om 15:42 heeft Richard Girard <aslsa.rng@gmail.com> het vo
lgende geschreven:
>
> Bart, Don't know if you've had any luck with this issue, but here are some
more things to check.
> Wire/Coil and Wire/Boot connection. Trim a quarter inch or so (6mm) from t
he each end of the wire so that the screw inside the coil and boot can get a
firm connection. While you have the boots off, check them for proper resist
ance, they should be 5 ohms. If they are too much more consider replacing th
em. You can get generics that are 1/10 the price Rotax charges. Test the spa
rk plug leads, too. They're wire core and s/b zero ohms.
> Test your mag switches for intermittent failure. Just use an ohm meter and
flip the switch a couple of dozen times and see if the switch has a failure
.
>
> Rick Girard
>
>
>
>
>
>> On Sun, Jul 12, 2015 at 2:19 PM, Guy Buchanan <gebuchanan@cox.net> wrote:
>
>>
>> I'm going to say broken ignition (not plug) wire. See this on the 912 all
the time. Use a continuity tester with needles to poke through the insulati
on. Work the wires to find the break.
>>
>> Guy B.
>>
>> Sent from my iPod
>>
>> > On Jul 12, 2015, at 11:45 AM, Bart Rond <bartrond@hotmail.com> wrote:
>> >
m>
>> >
>> > Hi fellow 2-stroke flyers,
>> >
>> > I am currently working on testruns and (hopefully) testflights with my r
estoration project Pulsar 1, equipped with Rotax 582 grey head.
>> > A few testflights had to be cancelled, because one of the two ignitions
failed in the run-up before take-off. So far, we could not find the cause o
f this failure.
>> > It does not fail constantly, sometimes it works and sometimes it doesn'
t!
>> > We suspect one of the ignition coils. Does anyone recognise this proble
m?
>> >
>> > Cheers, Bart
>> >
>> > Verstuurd vanaf mijn iPad
>> >
>> >
>> >
>> >
>>
>>
>> ==========
>> -
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com/Navigator?RotaxEngines-List
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>>
>
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> --
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>
> Believe those who are seeking the truth, doubt those who find it.
> -Andre Gide
>
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