I knew that I had read something before on this topic that had actually worked for me, and I got it at OSH last year from the TCM booth. It's an article that was reprinted with permission by the National Pilots Association.
The title of the publication by TCM is "Tips on Engine Care", Form X30548, Copyright 2000 Teledyne Technologies Incorporated, 00 TP/OPSTIPS/CAL 10K 07/00. Pages 5-9. (Uh oh, I don't do intellectual property law, but I think we're covered now, credit has been given, where credit is due!) None of this is my material, it's all TCM, thus there is no pride in authorship. If it's wrong, that's fine. I'm just passing along info I received from TCM.
I'll skip through the majority of the beginning of the article and get to what they say about how to fix a typical fuel-injected "hot" engine. I'll be quoting quite a bit here, so forgive the long-winded diatribe. Again, it's all TCM. You have to read all of this to get to the real answer. . . sorry.
Assuming the engine has been shut down for approximately 20 minutes and the ambient temp is 90 degrees F, the STANDARD procedure for a ROUTINE engine start "would consist of:
1. Mixture control -- full rich.
2. Throttle -- "cracked" or slightly open.
3. Magneto switches - on (if separate from starter switch)
4. Starter engage."
"Usually a small amount of liquid fuel will remain in the injection lines leading to the nozzles. As the engine begins cranking, this retained fuel is injected into the intake valve ports and drawn into the cylinders. Upon ignition, the fuel ignites and the engine bursts into life; then, just as suddenly as it started, it dies. A false start and the prima facie indication that a 'hot start' situation exists."
"Since the fuel lines inside the cowling are full of vapor rather than liquid fuel, the engine driven pump will not pump or 'remove' the vaporized fuel in sufficient quantity to support combustion. Therefore, the engine's refusal t continue running after the initial start up is simply due to fuel starvation."
. . . .
"There has to be a better way -- and here it is, in three easy steps:
1. Mixture control -- full lean or cut-off.
2. Throttle -- full open.
3. Electric auxiliary fuel pump -- on high."
"Relax for approximately twenty seconds and while you are waiting, here is how the solution is working for you. " (apparently, this author was never in my plane sitting on the ramp it hot temps, it's not too easy to 'just relax for 20 seconds
ed.)
"The electric fuel pump is taking liquid fuel from the tank selected and pumping it through the heat-soaked lines under the cowling. In its cut-off position, the mixture control prevents this fuel from reaching the cylinders. This is exactly what is needed at this moment: Now the fuel takes the alternate path and returns to the tank or header from which it came."
"During this process, the continual flow of fuel will purge the lines forward of the firewall of all vapors. Also this continued flow will reduce the wall temperature of the lines through which it passes. After approximately twenty seconds the fuel lines will have cooled sufficiently to retain the fuel in a liquid state after the pump is turned off."
"After twenty seconds, turn off the electric pump and make a normal start as follows:
1. Mixture control full rich.
2. Throttle cracked partially open.
3. Starter engage."
. . . .
"Just remember:
1. The mixture control must be full lean -- to prevent flooding and to force the circulating fuel to flow back through the return system.
2. The throttle must be full open -- because some single engine fuel injected aircraft incorporate switches in their throttle linkage to prevent the auxiliary pump from operating in the high position when the throttle is retarded.
3. The auxiliary pump must operate in the high position for approximately twenty seconds -- to provide sufficient time to adequately cool the fuel lines and components inside the cowling."
So there you have it folks. My fingers are tired from typing. That's the best info I have, and it worked for me on my 337A.
Keven
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