Fuel flow indication and MAP guage

[Jason Brown]

Hello, i just recently purchased a 1965 comanche 260 fuel injected and took it up for my first flight in it the other day. i noticed two squawks with the plane and was wondering if they are normal for the comanches or if they need to be addressed by a maintenance shop.

1. on engine start when priming the engine there is no fuel flow indication on the fuel flow meter. I use 1/2" throttle, aux pump on, mixture rich for about 3-5 seconds, and no indication. I dont want to flood the engine so I just continue with starting procedures like normal, mixture cut-off, aux pump off, and start the engine. It starts fine.

Am I doing something wrong? Is it a faulty fuel flow gauge? Is the aux pump not working properly? Is the normal among comanches?


2. i noticed that the MAP gauge is slow coming up to full power on take off and is slow showing any change in MAP when i change the throttle setting.

Can this be a faulty gauge? Is it possible the line is gunked up? Is this normal among comanches?


Please let me know what you guys think

thanks

[N3322G]

Jason,

Welcome to Comanche ownership. You can learn a lot about your new ride at CPPP see this website at http://www.comancheflyer.com/NS/cff_files/cf_ppp.htm There isn't a close one but talk to other Comanche owners and organize one for your location.

I have a fuel injected twin, IO320 engines - in the family for 42 years now. From my perspective, we have always gotten fuel flow when using the fuel pumps to prime the engine for start. The only time we haven't is when it wasn't working. Should have been squawked on the pre-buy - but then again, things break. I once shut-down after all worked perfectly and then fired up in 10 minutes and poof the right prop rpm gauge was casters up. I would take it to a Comanche experienced mechanic if possible.

On the MAP - bet you are right on gunk if the engine sound changes before it reacts.

Hope this helps.

[Gil Dahl]

Sounds like moisture is blocking both lines.
Gil

[Kristin Winter]

I wouldn't down the aircraft for it, but next time it has the cowlings off, have it looked at. It might be worthwhile blowing out the lines from the gauges going forward and making a general condition check.

[Zach Grant L1011jock]

The MP gauge is over dampened, either by oil in the line, or the damper screw on the back of the instrument is too tight. Both are easily remedied. The fuel flow issue may be a weak pump. The service manual, available under the tech tab, explains how to check it.

Zach