I have an interesting situation I would appreciate some input on… I recently relocated my Cessna 205 from Philadelphia to Seattle on an awesome 40-hour sightseeing adventure, everything went smooth and the plane performed great! After getting to Seattle, on my second flight from the new home base, I developed issues that manifested initially as fuel flow reductions.

In flight after about 45 minutes at altitudes of 1,500 or less I noticed the fuel flow slowly reducing to about 10 gph indicated. Enriching the mixture had no effect on the indicated flow and a reduction in power was felt. I turned on the boost pump and switched tanks and flows climbed slightly, I made an immediate precautionary landing at KBFI where their ARFF tends to be very eager and I was escorted to parking by fire trucks, ambulances, and airport vehicles. Awesome welcome to my new home.

I parked the plane for the night and went back the next morning to see if somehow this was a vapor lock issue I’ve heard about more commonly on the T210 models. Start and runup were fine, but upon rolling on the runway as I get above about 2100 RPM advancing throttle the power drops off significantly, I abort and head to the ramp again. Under the cowling I find that the injectors on the front two cylinders are loose and the distributor has a slight leak from the weep hole. Yesterday I finished replacing the distributor and re torquing the injectors and set out for a flight again. Same issue, getting towards full throttle the engine loses most of the power, reducing to about ¾ throttle restores power to what I’d expect at ¾ power. Even at full throttle and mixture full rich at sea level, indicated fuel flows never get above 12 gph, 22gph+ is normal.

At this point my brand new to me A&P suggests replacing the mechanical fuel pump. I don’t have any other guesses, but thought I’d post here and see if anyone has ever heard of similar issues or has any guesses…

Does the electric pump fix the issue? The main reason it’s there is to make the thing flyable when the engine driven pump gives up. Does the electric pump speed up when cycling the throttle in and out during preflight with the engine not running? Those micro switches need to be set up properly.


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The electric pump did seem to stabilize things when in flight, but I didn't do a lot of troubleshooting in flight. When attempting takeoff I did not switch the boost pump on/off during ground roll and aborted fairly quickly. I can go out and try cycling the throttle with the boost pump on and engine off to see what happens. I did flip the boost pump on during taxi back yesterday to see what happened and the engine nearly died so I quickly switched it off.

It seems tough to troubleshoot on the ground and I guess swapping the fuel pump should fix the problem but I'm not 100% confident. Engine is about 500 hours post field overhaul.

The fuel strainer on the 205 has a filter screen inside of it. I would not be surprised if it was clogged. It's a bit of a pain to get to up under the passenger side by the nose gear, but worth a shot. Don't drop the glass cylinder.

I think there is also a fuel filter between the firewall and engine about the size of a film can. Can't recall if this is my 205 or old 172...

The boost pump has enough pressure (on High, not on Low) to overfuel the engine. If you turned it on in flight and it didn't solve the flow problem, I'd question the mechanical pump being bad.

You could also have an issue with the fuel selector. Less likely if you switched tanks in flight, but the output feed of the valve could have gunk in it.

As an aside, I think it was your wife who was interested in getting some 205 folks together for some camping. I'm on the East side of Washington, but welcome to the neighborhood.

In reference to my above post, here is a long thread describing an issue similar to yours, and the small filter I mentioned.

https://backcountrypilot.org/forum/decr ... BVQhFJb_Hw

Wow, great find! I'm surprised I didn't come across this on my own. I'm looking through the maintenance manual and I'm not sure exactly where that filter is located. This really sounds like exactly what I have going on, I'll keep looking and hopefully Corey chimes in with some extra advice!

It is in the IO-470 manual, figure 69. PM me if you need a copy.

Well, this is a new one probably. I fixed the problem... I went back and started looking for the fuel filter, I noticed some oddly shiny metal in the back of the engine near the intake. My generator belt was rubbing on the mixture control arm connection for probably a significant amount of time the the pin failed. That meant that the interconnect control arm from the throttle to increase the mixture with the throttle was disconnected, basically at high power settings the mixture went to extremely lean and wouldn't run.

I replaced the cotter pin and test ran and then test flew the airplane, no new signs of rubbing but I'll be taking it in to have the generator adjusted to increase clearance and also installing the BAS harnesses I bought after the scare I had when the problem developed. Thank you guys for the help!

A cotter pin? Shouldn’t there be a roll pin in that mixture arm? Cotter pin would be too soft methinks. Or was it a missing otter pin that allowed a nut to back off? Either way very scary.


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Yeah there is an arm that interconnects the throttle and mixture control arm, at the elbow it has a hole that has a cotter pin in it. I had actually pointed it out at as a weak spot because of the clearance with the generator belt but it was said to be alright. I'm really hoping we can move the generator alignment enough to provide more clearance, and curious if anyone else with a 205 has noticed rubbing in that area of the top path of the generator belt.

Halestorm, you are here in Seattle too? Which airport are you based at?

I’m based at Apex and occasionally the Kenmore Air Harbor

Apex looks like a cool little strip, I'll have to try it out. I'm based at KBFI now and ready to go explore the awesome flying the area has to offer. Hopefully some BCP meet ups in the future?