temporary high fuel flow after startup

[larryb]

Hello:

 

     This has happend twice now, once a couple months ago, and once recently. I have an 84 J with an IO360. After startup my JPI FS450 has showed high flow at idle. Normally idle is around 2 to 2.5 gph, I was seeing 4.5 to 5 gph. After a minute or two, flows returned to normal. The engine ran normally during this time. I haven't seen any evidence of a leak. I would think if the engine was getting 2x the flow at idle, it would hardly run. If this happens again, I plan to do more testing, sweeping the mixture control, boost pump, etc. I initially suspected the flow transducer, but am now wondering if there could be something else causing this issue. Has anybody else dealt with a similar issue?

 

Thanks, Larry

[ArtVandelay]

Did you check the fuel pressure?

After start, as you lean, does it go down?

I assume you get book values for FF at cruise?

[larryb]

TJ:

 

     My fuel pressure gauge is not reliable. The trandsucer is bad, and no replacements are available. I have a new JPI 900 sitting on the shelf, but I haven't had a window of time for the shop to install it yet.

 

     The high flow indication only lasts a minute or two, then flow indications are normal. I get normal flow indications in flight. If it happens again I need to do more experiments with the mixture. Last time it happened, by the time I had finished other tasks the indications were normal, so I can't answer your question about what happens as I lean.

 

Larry

[N201MKTurbo]

It may just be fuel vapor in the fuel lines. Bubbles will make the sensor read high.

 

Once the fuel flow stabilizes, shut down the engine and try it again.