914 Turbo Fuel Pump

The only type of fuel pumps we've encountered that produce these "clicking noises" are the cube-style fuel pumps, typically aftermarket. Therefore, it's crucial to verify that you indeed have the correct Rotax 914 fuel pumps, as this clicking noise is unusual for them. The Rotax 914 fuel pumps are a vane-type with a spinning rotor internally (No internal diaphragm). Even when they fail or have issues, we have never heard them "click". 

Concerning the Rotax 914 fuel pumps: If fuel has passed through the fuel pumps at any point and then sat idle for a period, they could become gummed up with varnish residue from the remaining fuel. In such cases, no Rotax protocol specifies how to clean them, and attempting to do so could risk causing further damage to the fuel pump, even if you can get them to work afterward. However, it's worth noting that Rotax pumps from that era were generally reliable, even after prolonged periods of inactivity.

Rotax recommends replacing the 914 fuel pump every 5 years.

The part number for a new pump is 881365 (FUEL PUMP SET PACKAGED).

Given that the fuel pump is crucial to the engine's function and is a critical component, it's wise not to take chances with a potentially faulty pump. It's better to err on the side of caution and replace it to ensure continued safe operation. Another crucial aspect often overlooked and neglected is the presence of a pre-filter on the intake connection of Rotax fuel pumps. This pre-filter requires removal, inspection, and cleaning if it becomes plugged. While the aircraft fuel system typically includes a fine fuel filter before the fuel pumps to offer protection, it's still worth mentioning the existence of a filter screen inside the fuel pump that should also be inspected.

Regarding your location, it seems your profile states you are from New Zealand?

According to the Rotax Dealer Map, there are a couple of Rotax service centers in your area, and it may be worth giving them a call to see what additional help they can offer you.

Thank you so much for your reply,

I should have provided the following information.

All three fuel pumps are new and have never had fuel run through them.

The primary pump makes a buzzing noise when powered-on, whereas the secondary pump makes a SINGLE click when power is applied and so does the new spare pump, but they make no buzzing sound as if they are running.

You did not confirm whether the standard fuel pump that I have which was in the picture has since been superseded and if the kit with the adaptors is available from an online supplier - can you confirm please.

Is it normal for an unused pump for the rotax engine to fail without being used (perhaps that it is why it was upgraded ?)

Many Thanks

Regards

Trevor

Hi Trevor,

I can’t see a photo attached to your original post.

Try applying some light percussion around the pump body using a small tack hammer or screwdriver handle and a piece of timber or similar (to spread the percussive load) when power is applied to the pump. Check polarity first as they don’t like running backwards. The rotor could be just stuck, the bearings and/or vanes having dried out since manufacture. If you can introduce just a few drops of clean fuel into the inlet before trying this, it might help too. When it does start, I’d suggest not running it too long “dry” as that could do some damage I think. Obviously you need to be careful not to damage it by striking too hard but we have found this works to solve the very problem you describe with older, unused pumps.

Cheers.

G'Day Trev,

Your pumps problem can only have two causes/solutions.

Its either faulty (bin it!) or stuck due to long-term inactivity.

For the latter, try the Des (above) shock technique but do not be too forceful - many small percussive hit rather than a large hit.

If the Des technique doesn't work -

Liberally lubricate the innards with a light oil. I do not agree with the Des advice on using fuel, unless the pump is connected to a fuel supply.

1. Then try compressed air into the IN port. You may have to make up a temporary adapter to do this. You should not require electrical power to do this. Use power after confirming vane free moving. Do not run vane dry.

If this should fail:

2. If you can see, even part of the vane/rotating mechanism through either IN/OUT port, you may be able to move the part using  a small screwdriver/awl/ Alan key or similar. Even a small movement will likely unstick the internals.

Good Luck!

Hi again,

If all of the above fails to resolve the issue and you decide to replace your pump/s with new from Rotax, please read SI-914-035 linked below as in 2019 the pump design was changed and you would need to rework the pump hose and electrical connections (as noted in paragraph 1.13 of the SI ) if you have them already in place. I’m unsure as to whether Rotax agents would still carry the old design after so long. 

https://rotax.my.salesforcesites.com/DocumentsSearch/sfc/servlet.shepherd/

version/download/0681H000009TmEGQA0?asPdf=false

The old pumps (that I assume you have) are available from numerous suppliers. I believe the pumps were Pierburg part number 7.21440.78.0, used in a variety of European cars but please do your own homework to confirm that part number against the pump specifications listed in the SI if you decide to go the non Rotax way.

Cheers.