Did some more testing today.
First fired it up after the mods I did to the tanks in [link=http://www.rcuniverse.com/forum/fb.asp?m=9373056]Post 73[/link]
Got 110K rpm at 6,2pw just as the last time[&o]
Then we tried to blow as hard as we could in the vent line while engine was running. Same 110k rpm.
Then we connected the fueling station and ran it at full power while the engine was at full throttle, eliminating any vacum on the suction side since the filling goes directly to the header tank and is pumping more than the engine consumes. Same result, 110K. Maybe 200 rpm's more.
This makes me pretty sure that the problem is not on the suction side of the pump.
Then I did the bottle test as Oliver suggested. I marked of 750cc and 1000cc on a soda bottle. Unplugged the fuel line from the front of the engine, leaving the fuel filter and valves still in the system and meassured how long it took to pump 750cc in to the soda bottle. All fuel tanks in the plane was full as in the live test.
It took 52 sec to reach the 750cc mark @ 5,5pw. 1 liter was reached in 1,11 sec. Making the fuel flow about 850 to 900 cc's a minute.
Without the engine connected I assume it's pumping more because there is no restriction in form of the engine injectors building up the fuel pressure...?
Did not Carsten in Denmark get over a litre a minute doing the same @ pw5,0 without the valves??
I have not seen any signs of cavitation or air passing through the system at any time during any of theese tests.
Fuel system is as follows: Two side tanks feeds a centre tank via seperate lines of XXL tygon and 5mm brass tubes in to the tank. The centre tank feeds the PST trap via a 5mm ID clunk and 5mm brass tubes through tank and xxl tygon.
Then it's the PST trap > Pump > Filter (2,5 mm ID) > Festo 4mm barbed Y > fuel and start valves > engine.
Then I switched to another pump, the same Husel pump NIB, but with a bigger suction nipple., Same result, 52 sec to reach 750cc.
Then I fed the pump directly from a BVM overflow tank eliminating the whole tank system in the plane and the PST trap. Same 52 sec. to reach 750cc.
Then decided to by-pass the fuel valve since I knew it's the smallest passage in the whole system with only a 1,5mm ID nipples.
Connected the hose right after the fuel filter (which is 100% clean and drilled up to 2,5mm (was 1,8) ) The time to 750cc now was 40 sec instead of the 52 sec on all the other attempts.
Took the valves off and blew through them with my mouth. Could not tell any difference in flow between them. Tried to drill the nipples out to 2mm on the fuel valve, but one of them broke when screwing them back on to the valve because there was not a lot of material left under the threads[:@]
So now I have decided to rip the whole system out of the plane and run it in a bench. I have replaced the fuel valve with one from a Merlin engine. That valve is the same type that a friend of mine has on an older P-200 ans is much bigger than the small ones now used by JetCat.
Running it in the bench, I can easely by-pass the valve while the engine is running with two Festo Y-pieces, a piece of tubing and a clamp.
I feel I am really running out of options now, and that I have eliminated just about every part of the fuel system one at a time. The only change in results I got was when we ran the fuel pump without the fuel going through the fuel valve.
I really, really hope that the bench run will show if it was the valve or not. It could be OK now with the new valve, but if it's not, then I'll by-pass the valve while the engine is running.
One thing is for sure. This is not fun at all. Taking the whole fuel system appart and putting it back in the tight F-16 several times now has made a lot of fuel spills and mess all over the nice and clean install I had[&:]. Probably have to rip out everything and do it all over again[:@]
The one thing I really don't hope, is that it is something wrong with the ECU or the engine itself. If things have to go back to JetCat , with the speedy customer service I have seen so far, I will probably be without an engine for a year or so[:@][:'(][:'(]
Sorry about the mood, but I am just so fu*** fed up with this P200SX now that I could just about flush it!
Any educated suggestions are very wellcome, though
What do you say Oliver? Please talk to me
