Excessive fuel pressure revisited

by Mike Hoare in 912 / 914 Technical Questions 12 years ago

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Re: Excessive fuel pressure revisited

by MARK JACKSON » 12 years ago

MARK JACKSON

12 332 11

I would say that replacing the fuel needle valve stopped the leak due to a better seal and not a stronger new spring. The spring just acts as a damper.

Mark

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Re: Excessive fuel pressure revisited

by jay white » 12 years ago

jay white

36 97 23

I read the post and the refrence to my own problem. I had multiple issues and probably caused some of them through shotgun troubleshooting instead of systematic troubleshooting. I got a pump that was factory tested by a very helpful mechanic at Lockwood.

The final fix to the problem was this, Intalled a vent line, auxilliary fuel pump, new engine mounts to stop the shaking, (mine were 12 years old static) The plane runs great. 80 hours since repair,

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Re: Excessive fuel pressure revisited

by david bonnar » 12 years ago

david bonnar

1 18 34

Hello team,

I installed the 'new' style fuel pump with drain line etc. on my 912ULS and note that fuel pressure is fine until final, then goes up to 6+ lbs triggering alarms. It remains high to touchdown, then settles back down. Same hoses, have a return line, with the only addition being the new drain hose for the new pump.

I imagine the change to nose-low attitude on final rolls fuel forward, but never had anytihng like this happen before. The old pump didn't behave this way. Are there any issues with the 'new style' pump that I might not be aware of? Any tips, tricks or ideas?
.dxb

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Re: Excessive fuel pressure revisited

by Roger Lee » 12 years ago

Roger Lee

127 5.2k 4.78k

Hi David,

When this new pump came out there was an issue at first, but was corrected quickly. During a lot of pump testing down in the Bahamas the fuel pressure senders were checked too because they found so many of the senders with inaccurate readings. Before I worried too much about the pump you may want to spend about $30 on a new sender and try it. There are more false readings out there than people know. The new pump should be right around 4.5 psi and with your individual set up could vary just slightly. If you run an electric pump with it then that may increase about .5 psi. The VDO sender is supposed to read between 0-30 psi so we are down at the low end of its range. 1 psi can make a difference in an alarm. If we were more mid range at about 15-22 psi then 1 psi error wouldn't be a big deal. I see many aircraft that have Dynon D120 EFIS setups. When you turn the system on cold many read .4 to 1 psi without any pressure at all. Try a new sender and if it really comes down to 6 psi it shouldn't really be an issue if your carbs are in good shape. If it goes well over 6 then you need to track down the real problem. (pump, sender or gauge)

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

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Re: Excessive fuel pressure revisited

by Pietro Rebuffini » 12 years ago

Pietro Rebuffini

4 19 6

See new engine manual (heavy) about new fuel pump pressure....

Fuel pressure
The fuel pressure must not exceed a maximum of 0.5 bar (7.26 psi) . The pressure and functional efficiency of the fuel system can be checked with the new fuel pressure gauge kit part no. 874234.
:blink:
Bye
Pietro

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Title	Category	Replies
Low fuel pressure	912 / 914 Technical Questions	7
Fuel Hoses	912 / 914 Technical Questions	27
Fuel System Pressure Testing before engine start	General Tech Discussion	1
Oil pressure senders	912 / 914 Technical Questions	3
Mechanical Fuel Pump & High Wing Aircraft	912 / 914 Technical Questions	2

Excessive fuel pressure revisited

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