PCM 351 Vapor Lock Issues
Well guys, had the boat out for the first time and it ran great when cold start and cruising, but after sitting and pulling skiers it gets the dreaded vapor lock. Even died on me when I idling back into the marina. I can restart it but as soon as I put it in gear it stumbles and dies.
I searched and see tons of different answers so I thought I would start a fresh topic to get all ideas.
This is a fresh rebuilt 351 so I can eliminate that. Carbed motor.
1. What is the correct thermostat, 140 degree or 160 degree? Mine runs 160 and pushes 170-175 when the issue happens.
2. Phenolic spacer and heat shields- are these band aid fixes or do they actually work?
3. Mechanical fuel pumps - obviously this is bolted to the side of the block and soaks a lot of heat. How did they deal with this in the older days? Is ethanol content in fuel becoming a big issue?
4. Fuel line insulation - I assume this will help? Any one gone this route?
PCM 351 Vapor Lock Issues
Do your self a favor and a cheap one . Put a inline pressure gauge and see what the actual fuel pressure is . I live in tx and it's very hot most days . Never had vapor lock . But how do you know it's vapor lock ? Do you have clear lines ?
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PCM 351 Vapor Lock Issues
Stumble like pop back through carb ? You need to WOT when it stumbles for few short burst . To see what is actually happening . Lean will pop back through the carb , rich will load the engine up . Check the color of your plugs start with cyl #1 and just note what color is what . Chiltons manual or the enter web will have charts to tell colors of plugs . I have a stumble from time to time on my edlebrock but fuel pressure is solid and the cap was the culprit . Also if you have a volt meter check your voltage at the coil + when you see the engine stumble . Not hot enough spark will cause the same symptoms I always hold a flat head to the block and back off 1" to see if it will spark to the block and make sure it's fat spark . Touch your coil how hot is it ?
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