Suzuki DF90 runs for 2 seconds then stalls

[jumpjets]

I'm posting for a neighbor. I'm a merc I/O guy, and my outboard knowledge is limited. My Neighbors fuel injected Suzuki DF90 4 stroke 4 cylinder outboard stalled last week on the river and hasn't run since. Every time we try to start it, it will start, run for 1-2 seconds, then quit. If we open the throttle immediately after start, it stalls immediately. The ECM is giving him 2-4 code, which is a bad crank position sensor.

We've done the following troubleshooting:
-replaced all the fuel lines. (they were nasty and deteriorated, flaking apart from the inside)
-replaced the crank position sensor, since the code told us to do so.
-pulled the spark plugs to check spark. All are firing as expected.
-pulled the fuel rail off to check the injectors. All 4 injectors give a good v-shaped spray as expected. (these are his words, not mine. He's an older, self proclaimed "carburetor dude". I'm a fuel injection guy, so I probably ought to see this for myself)
-Sprayed ether into the throttle during start. When we did this, the engine would stay running.

The ether test tells me that the engine is starving for fuel. Do you guys have some more recommended things to check and troubleshoot? So far, nothing we've done is helping.

 

[chrisp929]

I’d verify fuel pressure. You know it runs on ether. Which clearly indicates a fuel issue. Run in that direction. Clogged fuel filter? Time to replace? You did say the fuel lines were falling apart on the inside! Consider a new fuel pump if cheap enough. How old is the outboard?