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New fuel pump

in 912 / 914 Technical Questions 13 years ago
Hi All,

Just a quick note about the new Rotax fuel pump. The first production pumps did have a little issue at times with high fuel pressure and I understand it was from an issue at assembly and not the actual design. The newer production models don't have that issue. If you do happen to get one of the new fuel pumps that are to high in fuel pressure then send it back and they will be happy to replace it. You should always check the fuel pressure when installing a new pump and or an electric pump. Many have fuel pressure gauges in the cockpit and that works. If you don't then hook up a mechanical gauge and check the pressure at cruise rpm (i.e. 5000-5300 rpm) on the ground.

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

  • Re: New fuel pump

    by » 13 years ago

    Hey Roger, Thank you again for the update, I did get an email from the distributor today and they concur with my analysis. They were very proffessional and said we would be talking tomorrow about replacement of the bad pumps.
    JaY
      
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  • Re: New fuel pump

    by » 13 years ago

    Hi Roger,

    Last July, I installed a new fuel pump (the one made by BCD in Italy, Rotax P/N 893110, S/N 11.0274). Fuel pressure was ok at full power and at cruise, but too high at idle. I was showing 6 psi at idle with the auxiliary pump turned off, and 6,2 psi with the auxiliary pump on. This is clearly above the maximum 5,8 psi specified by Rotax.
    After 61 flight hours this new pump started to leak oil through the drain hose. So I installed a new pump (replacement under warranty by the french distributor). This pump (S/N 11.2909) is giving the same level of pressure than the first one: 6 psi at high idle and around 5 psi at cruise. I am sure of the reading as I have made a calibration of the gauge and it is accurate in the 5-6 psi range. So I doubt that Rotax has done something about the pressure delivered by these pumps. I cannot understand that Rotax had a new product developed which does not comply with their own specification. The question is: is it safe to fly with this high fuel pressure?

    Now regarding the oil leak: this for sure comes from a defective seal between the shaft and the pump body which allowed the oil from the gearbox to enter the pump. I was lucky to detect the issue before it allowed all the engine oil to flow overboard.

    My personal conclusion is that the only advantage of the BCD pump over the AC and Pierburg is the addition of the drain fitting which allows any possible fuel or oil leak to be drained to the bottom of the cowling instead of flowing on the hot exhaust pipes, causing a high risk of fire.

    Regards
    Remi Guerner
    Europa F-PGKL, 912 ULS-FR
      
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  • Re: New fuel pump

    by » 13 years ago

    Hi Remi,

    Rotax knows some of the first production pumps out there were bad due to poor diaphragm installation. I'm sure there are still some out there. If you got another one then change it out. The problem has been rectified, but a psecific dealer may have several bad ones. The max fuel pressure is 5.8, but the carbs can usually handle up to 6.2 if they are setup right inside, that said I would not be using a pump over the 5.8 max. If you are showing over 6 psi with the second pump I would at least hook a a mechanical fuel pressure gauge to double check the reading before saying my system is good and the pump is bad. It's always better to rule out all possibilities no matter what your head may be telling you. I have been fooled more than once. Rotax is taking care of all warranties with this pump.
    Regarding the leak; you should fill out a Service difficulty report (aka Customer Service information report CSIR) which is found on this website under the Support tab and send it in so things like this can be documented so Rotax can see if there are any trends. If we as a group don't send these documents in then Rotax will take a long time to figure it out and fixes are greatly delayed.

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

      
    Report

  • Re: New fuel pump

    by » 13 years ago

    Roger,
    These pumps being traced through their serial number Rotax should be able to clearly state what serial numbers are good or not. Do you know?
    Based on the S/N of my two pumps, 11.0274 and 11.2909, I assume that Rotax has produced 2635 pumps in between and therefore the last one should be a very recent one. Can you please confirm that?

    Remi Guerner
      
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  • Re: New fuel pump

    by » 13 years ago

    Hi Remi,

    I'm sorry I don't know.

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

      
    Report
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