mshafer
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83 Saratoga turbo TIO540-S1AD engine, intercooler. Overhauled in 2012, 660's ish hours since overhaul.
Since I bought the plane and started flying with the overhauled engine, there has been two anomalies with the operation of the plane.
First, when landing and taxing back, if the outside temperature is hot, >90F, when the throttle is pulled back to idle, the engine will quit regardless of where the mixture control is set UNLESS the electric fuel pump is turned on. Discussion with the engine rebuilder and the diagnosis is vapor locking when really hot. My technique is to leave the electric pump on taxing back in on hot days. this has been doing this since day 1.
Second, in the air, switching fuel tanks in cruise, I turn on the electric pump, switch tanks, delay 30 seconds and turn electric pump off. I have noticed, in cruise, when I turn on the electric fuel pump, there is a surge in GPH briefly to about 1 extra GPH or so then settles back down usually .2 GPH higher than with the pump off. The surge is quick, 2 - 3 seconds. When the fuel pump is switched off, the fuel flow returns to the setting before the pump cycle. This has been doing this since day 1 also.
New Symptom. Starting up when the engine is ambient temperature, 65F - 80F, I turn on the electric fuel pump, open the throttle, push the mixture up till I see a bump on the fuel flow meter, close the mixture control and start the engine. When it fires, I push the mixture control to full rich until all cylinders are firing (JPI 830 monitoring), turn off the fuel pump then lean to smooth idle. This has worked fine everytime until recently. Now, same procedure and when I turn off the fuel pump, engine acts like the mixture control has been pulled to -- almost -- full lean, slows, coughs and regardless of where mixture control is, continues almost quitting UNTIL I either bump up the throttle to high idle OR turn on the electric fuel pump. Once the engine has been running for a minute or two, the problem is gone.
Talked to the Engine Rebuilder and my Mechanic, Both said -- air in fuel maybe -- Both have never seen this before. No fuel leaks noted, the fuel pump is a -M pump that was modified for the AD compliance.
Just seems to coincidental to me all these three anomalies seem fuel related ?
Since I bought the plane and started flying with the overhauled engine, there has been two anomalies with the operation of the plane.
First, when landing and taxing back, if the outside temperature is hot, >90F, when the throttle is pulled back to idle, the engine will quit regardless of where the mixture control is set UNLESS the electric fuel pump is turned on. Discussion with the engine rebuilder and the diagnosis is vapor locking when really hot. My technique is to leave the electric pump on taxing back in on hot days. this has been doing this since day 1.
Second, in the air, switching fuel tanks in cruise, I turn on the electric pump, switch tanks, delay 30 seconds and turn electric pump off. I have noticed, in cruise, when I turn on the electric fuel pump, there is a surge in GPH briefly to about 1 extra GPH or so then settles back down usually .2 GPH higher than with the pump off. The surge is quick, 2 - 3 seconds. When the fuel pump is switched off, the fuel flow returns to the setting before the pump cycle. This has been doing this since day 1 also.
New Symptom. Starting up when the engine is ambient temperature, 65F - 80F, I turn on the electric fuel pump, open the throttle, push the mixture up till I see a bump on the fuel flow meter, close the mixture control and start the engine. When it fires, I push the mixture control to full rich until all cylinders are firing (JPI 830 monitoring), turn off the fuel pump then lean to smooth idle. This has worked fine everytime until recently. Now, same procedure and when I turn off the fuel pump, engine acts like the mixture control has been pulled to -- almost -- full lean, slows, coughs and regardless of where mixture control is, continues almost quitting UNTIL I either bump up the throttle to high idle OR turn on the electric fuel pump. Once the engine has been running for a minute or two, the problem is gone.
Talked to the Engine Rebuilder and my Mechanic, Both said -- air in fuel maybe -- Both have never seen this before. No fuel leaks noted, the fuel pump is a -M pump that was modified for the AD compliance.
Just seems to coincidental to me all these three anomalies seem fuel related ?
