IO-540 sudden death

I have an IO-540 with a Bendix servo and spider. Last Fall my first startup went ok with exception of sudden death to the engine after running about five minutes. I traced all the fuel lines, screens, filters and and found nothing. I did a fuel pressure test on the pump and seemed ok but it came with the engine so I replaced it. I replaced the fuel distributor diaphram as well. EFIS show fuel warning 3 psi. Switched tanks, no joy. Any thoughts?

This may be a bit left field, but is the new pump definitely high pressure and not low pressure? It has happened to someone on here previously.

gnorm said:

I have an IO-540 with a Bendix servo and spider. Last Fall my first startup went ok with exception of sudden death to the engine after running about five minutes. I traced all the fuel lines, screens, filters and and found nothing. I did a fuel pressure test on the pump and seemed ok but it came with the engine so I replaced it. I replaced the fuel distributor diaphram as well. EFIS show fuel warning 3 psi. Switched tanks, no joy. Any thoughts?

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Did you do a fuel flow test before first start? Getting the fuel lines primed properly takes some effort.

To state the obvious.....but the fuel tanks are venting properly, right?

Fuel Line?

You don't have one of those bad fuel hoses with the rubber "flapper" do you?

DId you trying running it with the boost pump on? That would take the mech pump out of the mix. What do you mean by sudden death? Was the engine ground run for an hour or two?

I would disconnect the fuel line at the servo and run the boost pump for a minute or two to confirm the health of the fuel delivery system. Then, next start attempt use the boost pump.

Larry

Not sure what is meant by "traced" the fuel components... Did you simply verify they were installed correctly or did you crack them open and note fuel flow?

But to foot stomp Larry's suggestion, did you do a fuel flow bottle check of the injectors? Thats the quickest way to verify overall system integrity. If that goes good, then the "sudden death" troubleshooting gets a bunch easier

Your 3 psig fuel pressure is the smoking gun. I’d go after that first. After that (as has already been recommended) the simple shot glass flow test is a quick way to check your system.

An IO-360 had a problem with one cylinder running very lean, but of interest the problem moved once between two cylinders. The photos show the result of the fuel test. It turns out this was a “maintenance induced problem”. After a couple of decades of perfect operation the owner sent in the system for overhaul. In the process a chunk of crud got into the spider. It was enough to restrict flow at idle, but not at power.

Carl