Twin Engines Emergency Start Switch

Craig Lescombe

Craig Lescombe

Member
May 15, 2019
51
Windsor, Ontario, Canada
Boat Info
1990 350 Express Cruiser
Engines
454 CID / 7.4 Liter Twins
Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
 
I would have to say your switch for port engine is bad.... But don't hold me to it... Test it first..
 
Easiest first step would be to check your batteries and alternator. If you're getting wicked low voltage on the port side it would make sense that it won't run without getting 12V from starboard (when the emergency start switch is engaged).
 
Craig Lescombe said:
Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
Click to expand...

First, turn off the battery charger if it's on. Now try it.

If you are getting the same result, check all connections from the battery to the engine including at the emergency start solenoid. Take a emery board or sand paper and clean them very well. Clean all negative post on engines. Clean post and terminals on batteries.

Have you load checked your batteries?
 
Engine should keep running off of alternator output. No alternator output the engine dies. Almost certainly a bad alternator.
 
hottoddie said:
Engine should keep running off of alternator output. No alternator output the engine dies. Almost certainly a bad alternator.
Click to expand...

Not really. I had the exact same problem on my boat this summer. Alternator was producing power, new batteries, replaced emergency solenoid, cleaned terminals, etc. Problem was still there.

As soon as I turned off the battery charger the problem went away.
 
At idle speed the alternator will not produce enough power to run the 12 volt items on the boat and thus will draw down and your engine will stop. It happened once to us. We were in area we needed to either stop or go very slow so we would hit a set of rapids at slack tide. After an hour or so of 600RPM engine stopped. At 1200 RPM the batteries started to charge again.
 
Check and clean the main ground wire going to the port engine.
 
C3B49088-512B-4AB9-94F5-014A419D1003_sRGB.JPG
Craig Lescombe said:
Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
Click to expand...
What happen if you set your throttle to 1500 RPMs so it does not idle down?
 
Craig Lescombe said:
Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
Click to expand...
Craig Lescombe said:
Hello All- Here's my situation. Turned port key - nothing - held down "emergency start switch". Engine cranked and fired up and continued to run as long as I had the switch held down - as soon as I let up on the switch, port engine idles down / stalls. Can repeat this multiple times in a row - same results - thoughts?
Click to expand...
I'm a little late to the thread, But usually when that happens it's a bad Ballast Resister
 
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