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Fluctuating Fuel Flow/Max TAS with 200HP

RViators,

I have an RV4 with a 200hp IO-360-A1B6 with a WW 200RV constant speed prop.

Two problems I'm experiencing and looking for troubleshooting advice:

Fuel flow problem: At full RPM, fuel flow can fluctuate anywhere between 12 and 18GPH. Fuel flow stables out when boost pump is turned on. I've read that this could be trash clogging the injectors, air leaking into the lines, failing mechanical fuel pump, fuel servo problem, or fuel lines being close to the engine and heat vaporizing the fuel causing erroneous indications.
Here's a video 20"/2400RPM, boost pump on vs off:
YouTube video of fuel flow fluctuations

TAS Problem:
At full power I'm only seeing at most 170KTAS, which for 200hp doesn't seem right. Another VAF member recommended checking that the tach is indicating prop RPM correctly, which is something I still need to do. I'm also showing ~18GPH at full power. Looking at the Beechcraft Sierra POH that this engine came out of, that seems very high for full power.

Looking for any and all advice!
Mikey
 
Do you have an EGT gauge? If yes, what does your EGT do when the boost pump is turned on?

If it falls, that would point towards the mechanical fuel pump. If it doesn’t change, keep looking elsewhere.
 
18 gal per hr full throttle on takeoff is certainly in the ball park, might even be a tad low for 200hp which could be closer to 19-20 gph.
 
.... I'm also showing ~18GPH at full power. ...

I use 15 gph as FF at max power in my 180 HP io-360, so adding 20% to that gets you to right at 18 gph.

I got this number using the lycoming values for 11 gph for 75% cruise power, which gives 14.67 gph, and I round up to 15 gph.

There are also lots of charts around that show similar numbers, but obviously there are a lot of variables, like your induction system, exhaust system, engine condition, etc.
 
I have a 200HP and see in the upper teens 17-19GPH at take off regularly.

Do you have a fuel pressure gauge as well, if so what is that reading?
 
Thanks for the comparison. Unfortunately, I only have fuel flow which seems to be based on pressure at the spider. I do have EGT and EGT seems to fluctuate while fuel flow is doing the same. Refresh rate on the JPI is too low to get good video of it. I took the cowling down yesterday and noticed 100LL dye around the fuel supply line at the servo, so I may go ahead and replace that line. There's no active leak there with the boost pump on though, so unsure if that's going to fix the issue.
 
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