Front Engine Running Lean

Cglencross · #1 10-01-23, 07:36 PM

Hello all,

I've noticed my front engine (NA) egt running hot and my fuel flow be a bit low.

The only conclusion I can come to is that its running lean. My only thoughts are clogged fuel filter and/or mechanical fuel pump.

Forgot to try and run the electric pump to see if that helped.

Thoughts?

Chris

FYI: I have stock injectors.

TomM · #2 10-02-23, 02:54 PM

Here are the things I would check not knowing if this came on slowly or all of a sudden:
1. There is a strainer on the pickup tube in the sump in the wing boom. Mine was full of junk when I first got the plane, an is the first line of defense
2. The gascolator is plugging
3. mechanical fuel pump needs work/adjustment. Cessna has a really good guide on checking the pressures on this fuel system. I have my A and P follow it on every annual.

I would check the following:

1. make sure you get full fuel flow on the ground power and mixture full forward.
2. If not, check with the electric fuel pump on HIGH. The mechanical fuel pump has an internal bybass so that if it fails, the electric one can pump right through it and maintain full engine power.

That may help everyone understand a little more about the situation.

Keep us posted

mshac · #3 10-02-23, 05:22 PM

Don't forget to check for intake leaks

Cglencross · #4 10-03-23, 10:24 AM

Thanks for the replies.

Action Items: Will look at all suggestions over the next week. I'll try to fly-it/ground run it on the weekend to give everyone a more complete picture.

Its really helpful thanks everyone.

Chris

sunnysky · #5 10-04-23, 09:45 AM

I have a G Skymaster non turbo.
I thought that the electric booste pumps are to aid starting only
and not to be used for other flight modes.
in over 40 years of ownership I've never used the electric " dukes"
pumps for anything else .
maybe it's different on other models ???

TomM · #6 10-04-23, 10:15 AM

The use of the electric fuel pump in flight is part of the emergency procedures. It is not normally used other than to start as you noted. Name: Screenshot 2023-10-04 091435.jpg
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Name: Screenshot 2023-10-04 091435.jpg
Views: 299
Size: 104.6 KB

But is does provide enough fuel to operate the engine

sunnysky · #7 10-04-23, 01:50 PM

yes. Tom M . your Skymaster is different to the G model.
we dont have auxiliary tanks. just a very simple two tank system
with a facility to select the feed to the engines from either tank.
but as we seem to both agree, the auxiliary pumps are only for engine
start or restart in the air.
not to try sort out low fuel pressures in normal operations.
the original contributor was suggesting using the electric pump in an non approved way

Joes · #8 10-05-23, 08:07 AM

Have your mechanic check the unmetered fuel pressure using the latest version of the SID97-3. Just a real good place to start.
Joe

RandyArizona · #9 10-05-23, 11:19 AM

Quote:

Originally Posted by Joes

Have your mechanic check the unmetered fuel pressure using the latest version of the SID97-3. Just a real good place to start.
Joe

Indeed it would be... IF.. the rest of the fuel / ignition system was known to be good.

Learjetter · #10 10-05-23, 11:04 PM

Quote:

Originally Posted by Joes

Have your mechanic check the unmetered fuel pressure using the latest version of the SID97-3. Just a real good place to start.
Joe

Just FYI: the 97-3 info was all superseded and incorporated into the TCM Manual M-0, available as a pdf from the TCM tech pubs site.

http://continental.aero/support/main...e-manuals.aspx