As the title indicates – anyone has one of these that they’re willing to lend out / part from? Preferably a 0-20psi if not a 0-60psi will do.
Shorrick – You plan on performing the TCM SID97-3F I suppose ?
I just lent my digital pressure gauge that I use for checking FI systems, should be back next week and since I’m on vacation for 2 weeks I could lend it to you.
That said, if you’re relatively sure that your fuel flow gauge is reading accurately then no need for theb ptressure gauge.
BTW : Best article decribing the drill for the SID-973F is from Paul New here : FI Article
Indeed I do. The thing is that a) i am not 100% sure about the gauge and b) in its wisdom Mooney doesn’t give FF targets for the unmetered pressure, just psi. And it is the unmetered pressure that is too low. The rpm counter I managed to get for 30 EUR but gauge pricing is out of this world.
Shorrick_Mk2 wrote:
in its wisdom Mooney doesn’t give FF targets for the unmetered pressure, just psi
Why is Al Mooney of any relevance here? It should be an engine thing only so Continental should be asked.
Mooney has a specific instruction for the set-up of the IO-550G. The Continental Sid says “see manual” but the manual doesn’t have unmetered FF settings either (as a matter of fact neither does the Continental SID).
Shorrick_Mk2 wrote:
Mooney has a specific instruction for the set-up of the IO-550G. The Continental Sid says “see manual” but the manual doesn’t have unmetered FF settings either (as a matter of fact neither does the Continental SID).
The “see manual” refers to the TCM – Continental Manual, not Mooney.
A good digital pressure gauge is just $100.
Here’s a selection: Dwyer digital
Look at the SID Table and you’lle notice that a given pressure reading = a given fuel flow for a given engine type.
Surely you have an accurate digital Fuel Flow gauge to cross check the pressure readings ?
At any rate, I wouldn’t over do this FI SID – the main idea is that the FF @ WOT / Max RPM near sea level is “in the red” on the FF gauge.
BTW, that’s the main problem: too many mechanics/owners/operators were reducing max FF cause it was “in the red” !
I have the TCM manual, but the FF reading is only given for metered pressure, not for unmetered. My issue is not the metered fuel flow which is correct (in GPH at max RPM), it’s vapor lock at idle as the pump and manifold are heat soaked.
I think it’s down to unmetered pressure having been set lower at the last annual. TCM says 8-10psi whereas Mooney says 9-11. The drop in idle flow is noticeable with a heat-soaked engine (eg. if I have to hold for 10 minutes as opposed to making a leisurely descent). I am working on the baffling to address part of that issue, but i’d like to make sure fuel pressure is also where it ought to be. On top of that setting it at the high end of the range gives you a more linear mixture when increasing throttle, not a sudden bump to rich when switching to metered from unmetered press.
As a sidenote, TCM has not amended the manual (as of February 2015) to include the SID amended settings, and that same TCM manual reports the IO-550G makes max power at 2700 instead of 2500… but who cares about precise figures, it’s ok I have the latest technology crankshaft right…
Shorrick_Mk2 wrote:
My issue is not the metered fuel flow which is correct (in GPH at max RPM), it’s vapor lock at idle as the pump and manifold are heat soaked.
What makes you think it’s vapor lock ???
Lot’s of gremlins are being attributed to vapor lock, a tort … IMHO, it’s probably the MOST maligned cause in piston GA …
What are your symptoms exactly ?
The symptoms are engine death on rollout / taxi (or if left at book 700 rpm idle until it gets hot).
It only happens when the engine is hot and throttle below 1’000 rpm. Cold engine flow at 1’000 rpm is 3.6 gph, dropping to 2.6 on a hot engine. Other than vapour restricting the flow I am at a loss for ideas.
Is that with the boost pump on ? If not, try it .
That said, those symptoms on the TCM IO-550 is usually caused by a bad fuel divider diaphragm.
They are rubber and like all rubber parts they get stiff and/or brittle and no longer function correctly after a few years.
When was the fuel divider last overhauled ?
edit: Also, 700 rpm idle is too slow for the big-bore Contis, I suggest you bump it up to 800 or so, and get used to putting a turn or two in right after you’ve controlled your roll-out.
