UnPossible
Well Known Member
Hey – I went for a flight this morning and my engine seemed to not be running as well as usual. It was hot here in Texas and I climbed out to 3,700 feet at 25 squared. #1 and #6 CHTs were just over 400 (which seems pretty normal). However in cruise at 23 squared, I could not run lean of peak without the engine stumbling – which is something new.
I have a Precision Silverhawk fuel injection system and two SureFly electronic ignitions.
When I got back home, I downloaded the data, and it looks like #5 cylinder EGT is quite a bit below the others (normally they are pretty tightly bunched). At this point I am thinking it could be a spark plug, an ignition or a fuel issue.
I started with fuel by removing each of the injectors and cleaning them (I did not see any debris, etc. in any of the injectors). While all the injectors were out, I ran a test to see if each cylinder is getting the same amount of fuel. I put 6 cups under each of the “spider legs” and with the throttle and mixture both wide open, ran the boost pump for 45 seconds or so.
What I found was a bit interesting….. cylinders 1,3 and 5 were getting less fuel than 2,4, and 6. Below is the data comparing the amount of fuel (by weight) relative to the lowest amount (#3).
1 4.1%
2 15.7%
3 0.0%
4 19.0%
5 5.8%
6 9.1%
I am assuming that it’s not normal for one cylinder to get nearly 20% more fuel (by weight) than another cylinder. If it was a clogged line, I’d expect one leg to be way lower than the others, but it seems strange for all of the odd cylinders to be flowing less fuel than the even ones.
At this point, I am wondering if I may have a problem with the flow divider. Is there a good way to flush out the divider? I’d love any thoughts as how to trouble shoot this further. Thanks.
I have a Precision Silverhawk fuel injection system and two SureFly electronic ignitions.
When I got back home, I downloaded the data, and it looks like #5 cylinder EGT is quite a bit below the others (normally they are pretty tightly bunched). At this point I am thinking it could be a spark plug, an ignition or a fuel issue.
I started with fuel by removing each of the injectors and cleaning them (I did not see any debris, etc. in any of the injectors). While all the injectors were out, I ran a test to see if each cylinder is getting the same amount of fuel. I put 6 cups under each of the “spider legs” and with the throttle and mixture both wide open, ran the boost pump for 45 seconds or so.
What I found was a bit interesting….. cylinders 1,3 and 5 were getting less fuel than 2,4, and 6. Below is the data comparing the amount of fuel (by weight) relative to the lowest amount (#3).
1 4.1%
2 15.7%
3 0.0%
4 19.0%
5 5.8%
6 9.1%
I am assuming that it’s not normal for one cylinder to get nearly 20% more fuel (by weight) than another cylinder. If it was a clogged line, I’d expect one leg to be way lower than the others, but it seems strange for all of the odd cylinders to be flowing less fuel than the even ones.
At this point, I am wondering if I may have a problem with the flow divider. Is there a good way to flush out the divider? I’d love any thoughts as how to trouble shoot this further. Thanks.