Skymaster fuel problem

[JMD]

We have had this problem since purchasing this aircraft last November. It is a T337B which has an intermittent fuel problem. At cruise the engine fuel pressure fluctuates and drops. Turning the aux pump on for about 1 min cures the problem for the rest of the flight. This problem occurs on both engines intermittently and not on every flight. Has anyone experienced this problem?

[Skymaster337B]

Since it happened to both engines I suspect the fuel. When was the last time the fuel filters were changed?

[Kim Geyer]

I would check the tank vents first. Then I would have the fuel pressure settings checked. Also check the referance line that runs from the fuel pump to the throttle body, if they leak, it makes the engine stupid stuff.
Kim

[JMD]

The vent lines were check along with the vent check valve which was checked for operation and correct mount position. Fuel pressure settings were also checked. I have not checked the reference lines for leaks, I will do that next. Could the fuel strainers cause this problem? John

[Roger]

Recently when my A&P was working on the front mag to fix what appeared to be a prob with the tach, he broke the protective coating that is around the fuel line near the mag. He went to lunch and came back an hour later and there was a pool of gas under the engine. He then traced it to a crached fuel line that was cracked for quite some time but the now broken plastic shroud kept the leak hidden while on the ground. However in flight it was sucking air which is why we had previously turned up the fuel pressure on that engine.

Suggest you check your hoses for a like problem.

[skymstr02]

AD Note 71-24-04 covers this subject:

http://rgl.faa.gov/Regulatory_and_Gu...F?OpenDocument