Jetguy
Well Known Member
Yes it does!
Here's the scenario. OAT 70 F or hotter, engine driven fuel pump in good working order, carbs balanced and in good working order. You come in from flying and shut down for about 15 minutes while you refuel then you head back out for some more flying fun. But when you throttle up for takeoff the engine runs ruff and you think your engine fuel pump just went bad. What really happened in this scenario is when you turned your master switch on for startup and fresh fuel from the electric fuel pump entered the engine driven fuel pump it vaporized because the engine driven fuel pump got really hot from heat transfer from the engine case.
Two ways to stop this from happening.
First, if it's hot out side and you are going to do a quick turn, leave you electric fuel pump running while you refuel. This will keep your engine drive fuel pump cool.
Second, during your takeoff roll after a quick turn your engine starts to run ruff at full power, abort, taxi back to the end of the runway, increase power to about 3000 rpm and choke the engine for about 30 seconds. Then turn choke off and try a full power run up, now the engine should run normally. What you are doing is increasing the fuel flow through the engine hoses and cooling everything down.
We were able to reproduce these scenarios many times today once my buddy and I figured out the problem and how to fix it. There is a time frame after you shut down when the engine heat in your cowl will peak and begins to cool off. If you wait till after this peak (no idea what the approx time would be) then you will most likely not experience this problem. The way you can verify this could occur in your engine is after flying shut down you engine and wait about 3 to 5 minutes, then put you ear next to the cowl opening in front of the engine driven fuel pump and listen for a few minutes, you will hear nothing. Then go turn on you master switch and electric fuel pump, go back and listen again to the engine driven pump. What you will hear is a sizzling sound of fuel vaporizing in the pump. After about 5 minutes the sound will go away as the raw fuel cools the pump. It seems like we never stop learning something new about these engines.
Here's the scenario. OAT 70 F or hotter, engine driven fuel pump in good working order, carbs balanced and in good working order. You come in from flying and shut down for about 15 minutes while you refuel then you head back out for some more flying fun. But when you throttle up for takeoff the engine runs ruff and you think your engine fuel pump just went bad. What really happened in this scenario is when you turned your master switch on for startup and fresh fuel from the electric fuel pump entered the engine driven fuel pump it vaporized because the engine driven fuel pump got really hot from heat transfer from the engine case.
Two ways to stop this from happening.
First, if it's hot out side and you are going to do a quick turn, leave you electric fuel pump running while you refuel. This will keep your engine drive fuel pump cool.
Second, during your takeoff roll after a quick turn your engine starts to run ruff at full power, abort, taxi back to the end of the runway, increase power to about 3000 rpm and choke the engine for about 30 seconds. Then turn choke off and try a full power run up, now the engine should run normally. What you are doing is increasing the fuel flow through the engine hoses and cooling everything down.
We were able to reproduce these scenarios many times today once my buddy and I figured out the problem and how to fix it. There is a time frame after you shut down when the engine heat in your cowl will peak and begins to cool off. If you wait till after this peak (no idea what the approx time would be) then you will most likely not experience this problem. The way you can verify this could occur in your engine is after flying shut down you engine and wait about 3 to 5 minutes, then put you ear next to the cowl opening in front of the engine driven fuel pump and listen for a few minutes, you will hear nothing. Then go turn on you master switch and electric fuel pump, go back and listen again to the engine driven pump. What you will hear is a sizzling sound of fuel vaporizing in the pump. After about 5 minutes the sound will go away as the raw fuel cools the pump. It seems like we never stop learning something new about these engines.