Date: 201512
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: Mixed
Light: Daylight
Aircraft: MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
Aircraft component: Pneumatic Valve/Bleed Valve
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed in Emergency Condition
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Level at cruise altitude (FL310; I believe) we received a L START VALVE OPEN message on the Electronic Overhead Annunciator Panel (EOAP). I instructed the First Officer (FO) (also the Pilot Monitoring (PM)) to run the QRH and that I would continue flying and take COMM 1 and 2. We had to initiate an immediate descent to maintain a safe airspeed. I requested FL200 from ATC. Because this would descend us into a line of thunderstorms; we began a right turn as well. After pulling breaker U-42 and completing the QRH; the EOAP message extinguished. Because of this; I elected to leave the left engine at idle for the diversionary approach and landing; instead of shutting it down.  Communicating with Dispatch and Maintenance on the descent was very difficult. They had a very difficult time hearing me; although I could hear them just fine.Level at FL 200; we were headed south I considered ZZZ to be the nearest suitable alternate in point of time. I briefed the flight attendants and passengers and set up for a long final for a visual approach into Runway 8 at ZZZ1.The approach was flown using single-engine procedures; since the left engine was not going to be moved out of the idle unless absolutely necessary. After landing and exiting the runway; I had Air and Rescue Fire Fighters (ARFF) visually inspect the left engine. They stated it looked normal. I and taxied to the gate.QRH is misleading and confusing. The QRH gives you the option of leaving the engine running or shutting it down. Had the EOAP message NOT extinguished; I would have elected to shut the engine down. The EOAP message did extinguish; but I could not confirm any potential damage that might have been done with the starter engaged at cruise settings for (at least) 15 seconds - even with normal engine parameters. I wanted the option of using the left engine; if necessary. The QRH needs to annotate the proper items to follow AFTER making the decision to shut down or continue operation. These are two very divergent paths and should not be listed as 'NOTES' - an afterthought at the end of the procedure.  If another QRH procedure needs to be run after the procedure you are currently running; THIS NEEDS TO BE STATED IN THE CURRENT PROCEDURE (see step 17; ENGINE FIRE; as an example.)If you elect to shut the engine down; QRH needs to direct you to ENGINE FLAMEOUT/FAILURE/SHUTDOWN. The top of the page properly directs you to further supporting QRH's after engine shutdown. If you elect to keep the engine running but at idle (as I did); there needs to be supporting items for this decision. The QRH contains crucial items for this configuration; but not all items are applicable. We were approaching 1300 lbs main tank fuel imbalance (1500 lbs limitation) before I noticed this. Why? Because opening the Fuel X-Feed lever is a necessary item; and only contained on a different page. Although we ran the procedure after noticing this; we had to intentionally disregard items not applicable. Furthermore; auto throttles cannot be used in this configuration. A dedicated procedure needs to be developed for START VALVE OPEN; along with printed guidelines to assist you in the 'shutdown/remain running' decision for that engine.Bottom line: If another QRH procedure needs to be performed after finishing the current procedure; the current procedure needs to explicitly direct you to any subsequent procedures. If any charts or tables are needed in a QRH procedure; they need to be printed directly in that QRH procedure. All references to the Aircraft Operations Manual (AOM) and procedures that have been obsolete for almost 4 years need to be eliminated. It is worth noting that I had already dealt with a pressurization emergency earlier in the day - same aircraft. I was the only crewmember from that flight continuing on. Prudence might dictate that when a crewmember has already run 2 Emergency QRH's in preceding flight hours earlier; they aren't pressured into accepting a later flight thatputs them within 30 minutes of their maximum duty day.




Synopsis: MD-80 Captain experienced a L START VALVE OPEN message during cruise flight. When the engine is reduced to idle thrust the light goes out and the flight diverts to the nearest suitable airport. The Captain believes that the QRH procedure could be more comprehensive and contains some outdated references.