I’d like to get peoples thoughts on the correct fuel pump flow rate for an FL350. I had some problems with mine which I eventually traced back to a partially blocked internal main fuel tank pipe and is now resolved but I read a lot of the helpful articles on here as I was trying to sort it. That said I came across numerous times the quote that the stock fuel pump should put out 4.5 US Fl oz / 10s starter or idle based on the Pilot manual spec. So just to check I had a look at the Pilot Manual and it says the following:-

Fuel pump flow capacity – 50CC (4.7US oz, 4.9 imp oz) / 10 seconds at idle

The issue I have with this is that 50CC is NOT 4.7 US oz, it’s 1.7 US oz so either the 50CC is incorrect or the 4.7 US oz is incorrect. I’m betting that the 50cc is correct as it’s the metric measure which is the manual’s primary units with conversions to imperial etc. I saw a lot of posts with people mentioning that they are only getting about 2 oz, well that could well be correct based on this. Another pointer is the replacement square Mikuni fuel pump that a lot of people have used with success on the FL350. This pump is specified at 14l /hr which is 39CC / 10 seconds or 1.3 US Fl oz / 10s, way less than the 4.7 but not that far off the 50CC. If we take into account that the FL350 is actually a 330CC Engine compared with the 397cc of the Pilot then getting 38CC instead of 50CC will likely be fine as the Engine is 17% smaller and the fuel supply is almost 20% less which makes sense and should work fine.

Am I talking BS here or do we think the 50CC or the 4.7 US oz is correct for the fuel pump flow rate, would like to know what others have found.

(FYI, when I resolved the blockage I now get just under 50CC on the starter for 10s using stock fuel pump and she runs great, no issues whatsoever. With the blockage I was getting about 20CC and she would start / idle but bog out as soon as soon as you revved her which all makes sense)

We have been down this fuel delivery road many times on this site.
I don't want to rehash this again, but I have a lot of experience with melted pistons and so have many others on this site.
In the past I did my flow test using just the starter. The problem with this method is that there were a lot of different set ups. It depended on your starter condition and your battery condition. A weak starter or battery gave suspect results. We (I) now do it at IDLE.

Flow rate:
I do it at 4.5oz in 10 sec at Idle.
If you are getting less than this you are in dangerous territory.
At wide open throttle you could get a lean out and melt a piston.
As for the 50cc you see in the manual it could be a typo. There have been other typo's in the various manuals so I would just disregard that.
Also of note is that the fuel system on an FL350 and FL400 has a bypass "T" that goes to tank. Excessive fuel flow goes to tank. Therefore the more flow the better to prevent a lean out condition and melted piston.
I have a couple of videos and youtube about this: https://www.youtube.com/watch?v=WT-rBlEb8Z4

Do what you want, it's your machine but I run 4.5oz in 10 sec at idle.
Also of note: AVGAS
You are on your own if you don't listen.
CO

Thanks for the advice CO. I did my flow test on the starter which as you say is not particularly consistent. I'll do it again now at idle and see what I'm getting. I do have transparent fuel hose on at the moment and can see plenty going to the carb and even more going back to the tank via the bypass T piece so hopefully I'm ok anyways but I'll check again based on your experience.

Stop !
I do this test without allowing fuel to go through the bypass valve.
What you do is remove the hose AT THE PUMP that goes to the carb and then put another hose on it that goes to a measuring container.
If you don't you could get wrong pump flow readings.
If you look at my videos that's what I do.
CO

Yes got it thanks, when I did the test i did it like you say straight from the pump. In normal operation I can see plenty going to both the carb and back into the tank, even at idle, so I'm hoping I'm ok and just getting a poor reading on the starter, but obviously want to check now properly based on your advice.

Also note to make sure your idle is set to the speed the manual says, too high or too low will effect the flow