912 fuel pump replacement

by jay white in 912 / 914 Technical Questions 13 years ago

I ordered a new pump for my 912F2 and the pressure was 7PSI.
I sent it back and ordered another pump and got the same problem. I re-installed the old pump that I took off for a leak and I got the recommended pressure of 5PSI.

Anyone using the "New and improved" pump? What is wrong?

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Re: 912 fuel pump replacement

by Roger Lee » 13 years ago

Roger Lee

125 5.12k 4.53k

Howdy,

Your old pump pressure is within specs, but sounds a little high compared to the average AC pump. You may just be getting a bad high reading. Double check the real pressure with a mechanical gauge. You don't need something expensive to do this. Get any gauge that reads up to 10 psi and put it in line and double check the pressure reading. I have seen many a fuel pressure gauge that was wrong.

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

Thank you said by: jay white

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Re: 912 fuel pump replacement

by jay white » 13 years ago

jay white

36 97 23

Thank you so much for the help today. I know you spent a lot of time with me on the discussion. I am confident that the problem can be resolved soon and I will let you know how it goes when the old style pump arrives and is installed. In the following months as the bugs get worked out on the new style pump and they become a desireable replacement, I will switch out.
Thank you again.
If you are in the neighborhood and want to stop in, I have a nice grass strip and a hangar that will keep your ride dry.
Jay

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Re: 912 fuel pump replacement

by Mike Hoare » 12 years ago

Mike Hoare

10 16 0

What was the upshot here? Are the new pumps pitting out too much pressure? I am having similar problems. Let me know how your problem resolved itself. Thanks, mike

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Re: 912 fuel pump replacement

by jay white » 12 years ago

jay white

36 97 23

My new pumps were putting out more fuel than Rotax recomends but not more fuel than the engine can safely and effectively handle. My new one puts out the recomended amount but I did add an electric back up pump per Rotax instruction.
My problem was mostly caused by bad engine rubber mounts that allowed excessive movement of the whole engine. It shook until the float bowls poured excess fuel out of the vents.

I replaced the mounts, added a fuel return line, installed an aux pump, and have put 80 hrs on it all with no problem. The new pumps have a recall on a hose but you can check rotax SBs. my pump was not in the bad batch.
What is the problem you are having and has anyone addressed it? Roger seems to be the expert on this stuff.

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Re: 912 fuel pump replacement

by Roger Lee » 12 years ago

Roger Lee

125 5.12k 4.53k

Hi Jay,

Glad you found your problem. They can be tough sometimes. During the 5 year rubber replacement I always recommend changing the rubber engine mounts too. When the mounts et old they get stiff or break down and cause the exact issue with vibration you mentioned.

I always tell my clients that just because the engine mount has not rotted off doesn't mean it's any good.

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

Thank you said by: jay white

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912 fuel pump replacement

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