912S starting problem

by Dudley Johnston in General Tech Discussion 13 years ago

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Re: 912S starting problem

by mike hallam » 12 years ago

mike hallam

3 40 0

Rui Melo's reply reminds me.

1)On my Rotax 447 (I know: different engine, different Bing) for starting, especially in the Winter, it's essential to blow into the carb balance pipe before turning the prop to suck in. If not she'll never go & the plugs remain dry. No matter how many prop. turns or squeezes of the primer bulb.

In fact it's such a good stating TIP it's in the Rans S4 blog [ http://ranss4s5tips.blogspot.com/ ].

I've never tried to do similar on my R912 as it's difficult to get at the carb pipe and usually not necessary to prime thus.

2) On my Rotax 912UL (Rans S6-116) the gascolator has a tiny almost imperceptible fuel weep {New gasket on order, not yet fitted). Result it's dry next time I go to start as are the lines rising to the pump, & no fuel mix is sucked in after fuel tap is placed ON until she's been cranked over quite a few times - before the one & only mechanical pump has fed the float chambers etc. Obviously I need to seal the gascolator PDQ. However it's a possibility to consider.

A very simple lack of fuel can inhibit start in both cases.

mike hallam.

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Re: 912S starting problem

by bill martin » 12 years ago

bill martin

10 757 0

I used to run onto the same problem occasionally. Blowing into the balance pipe works. It essentially does the same thing as a primer. By raising the pressure in the carb bowl, fuel is forced up into the carb throat. having even a tiny leak, especially if your fuel tank is lower than the carbs, can drain the fuel lines over a period of days. I just run my electric fuel pump a few seconds before starting the engine and starting is no problem.

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Re: 912S starting problem

by Rui Melo » 12 years ago

Rui Melo

0 4 0

Hi
Thank you for your help
Roger let me try to give you all the information you asked for:
-Fuel pump- peerburg 2PSI
-Engine is 7 years old
-Shock- OK it goes all the way
-Idle 1700/2000 rpm
-No throtlle when starting
-Starter-I bought the heavy duty
-Battery wire- 1cmm diam more or less 50cm long
-Plug 0,7mm gap
-Mixture srew -I have to check
-Battery- can not tell you exactly wich battery is but the same one is used by other fellows in the airport and works fine

Mike and Bill. I will check for leaks in the fuel line

Thanks again

Rui

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Re: 912S starting problem

by Roger Lee » 12 years ago

Roger Lee

127 5.2k 4.78k

Hi Rui,

You said your fuel pump only puts out 2 psi? If that is correct then the correct pressure should be 2.2 - 5.8 psi. The average seems to be around 3.1 - 4.5 psi. Could something be draining the battery over a few days?
Here is something to try; Have you tried to jump your battery with a much bigger battery to rule it out of the equation?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: 912S starting problem

by Rui Melo » 12 years ago

Rui Melo

0 4 0

Hi Lee
Thank you for your repply.
I used the pump under 2 Psi because it was what Rotax recommended in the past. I checked the operators manual and you are right.
I have another one that is 3,5Psi so I will install it this weekend. The battery is already beeing recharged.
I will let you know about the results.
Thanks again

Rui

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912S starting problem

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