I have just moved my aircraft to South Africa where it has under gone a full inspection/annual. I have just been closing everything up and doing the engine run.
Before I left UK, I had an issue on the last couple of flights where the fuel pressure would fluctuate and get low (around 15 psi) on the ground but was fine in the air. Putting the fuel pump on resolved the problem. On stripping down to move, I noticed that the bottom plate on the fuel pump was loose with 4 of the 6 screws unthreaded. I thought maybe this was the problem.
Before draining the oil, I did a run. Initially, it was a bit rough and the fuel flow was low. After a couple of minutes, it sorted itself out. Running was smooth and fuel pressure normal at around 26. I put the symptoms down to inhibitor oil in the cylinders and air in the fuel system and thought that the problem had been solved. After the oil change, I did a further run-up. Terrible! Firstly, fuel pressure was good and everything smooth. Then it went high - 37 - but the engine ran fine. No matter what RPM I set, it stayed constantly high. Then it dropped and I had the same symptoms as previously - fuel pressure low, engine stumbling but would pick up with more throttle but at times it was really rough. Putting the electric pump on would increase the pressure but it still wasn't 100% smooth.
This was a Aerosport IO540 which had been running SOOOO sweetly so you can see why I am totally hacked off! I am not very switched on with pistons being military all-jet trained but I suspect the issues could be fuel pump, pressure regulator or induction/injection. Any thoughts would be welcome.
EDIT: I have checked the serial number on the pump and it is not subject to any of the SBs.
Before I left UK, I had an issue on the last couple of flights where the fuel pressure would fluctuate and get low (around 15 psi) on the ground but was fine in the air. Putting the fuel pump on resolved the problem. On stripping down to move, I noticed that the bottom plate on the fuel pump was loose with 4 of the 6 screws unthreaded. I thought maybe this was the problem.
Before draining the oil, I did a run. Initially, it was a bit rough and the fuel flow was low. After a couple of minutes, it sorted itself out. Running was smooth and fuel pressure normal at around 26. I put the symptoms down to inhibitor oil in the cylinders and air in the fuel system and thought that the problem had been solved. After the oil change, I did a further run-up. Terrible! Firstly, fuel pressure was good and everything smooth. Then it went high - 37 - but the engine ran fine. No matter what RPM I set, it stayed constantly high. Then it dropped and I had the same symptoms as previously - fuel pressure low, engine stumbling but would pick up with more throttle but at times it was really rough. Putting the electric pump on would increase the pressure but it still wasn't 100% smooth.
This was a Aerosport IO540 which had been running SOOOO sweetly so you can see why I am totally hacked off! I am not very switched on with pistons being military all-jet trained but I suspect the issues could be fuel pump, pressure regulator or induction/injection. Any thoughts would be welcome.
EDIT: I have checked the serial number on the pump and it is not subject to any of the SBs.
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