1979 mercruiser 470 vapor lock

[Rinker captiva 206]

I have a mercruiser 470 in my 79 aristocraft 19 and I'm having troubles with restart after sitting on the beach. I have a clear fuel filter right before the fuel pump. I can see that the fuel kinda disappears out of the filter after sitting for a few minutes. I can take a towel and ring lake water over the fuel pump and watch the gasoline return to the fuel filter. My engine runs nice and cool, after cleaning the whole system out. It never gets above 160 degrees. I wrapped the metal line from the pump to carb with heat reflective shield. I did more experimenting one the lake this weekend and the fuel pump seems really hot after shutting the engine off. The line felt cool. I've done some reading and it seems like an electric fuel pump could solve the problem? I believe it gets hot from the intake manifold. Could i wrap the manifold with an exhaust header wrap maybe? I would like to keep the mechanical pump, but if the electric would solve the issue, I would convert it. Any other options?

 

[alldodge]

Clear fuel filter :facepalm:

Why you can see fuel come back if pouring water over the pump is not apparent. Pump was warm and cooling it down would cause fuel in the pump to condense a bit more. If anything maybe its pulling fuel from the carb, don't know, but like all things gas expands when getting hot.

If your beaching the boat then the bow is up higher, so more tilt on the carb. Is the carb leaking or when trying to start when hot out, does the carb drip fuel (flooding)? I don't see vapor lock

 

[kenny nunez]

One thing to check. Next time with the same scenario remove the flame arrestor before trying to start and have someone pump the throttle while you are looking into the carburetor and see if fuel squirts from the accelerator nozzles. That will tell you if the carburetor is dry. Are you using Eathonol free gas? If not then that could be the cause of the problem. I also have seen where the ignition "by pass" was not supplying 12 volts to the coil will cause a similar symptom on an engine that has been running then turned off for a short period. The following test can be done on a flush out to check the bypass circuit by connecting a volt meter to the + or bat side of the coil and watch the voltage when cranking, you should have 12 volts at that point and around 8-9 after the engine starts.

 

[Rinker captiva 206]

The original problem was a no start condition after being hot. I had then checked spark at that time. All good. And accelerator pump was dry. So we cracked fuel line. Fuel sprayed everywhere. Since then I have just soaked the fuel pump and lines with cold water. Starts good after that. If I shut the engine down for a minute it will start right up

 

[Rinker captiva 206]

Not using ethanol free. Where I live premium still has 10 percent..

 

[alldodge]

The original problem was a no start condition after being hot. I had then checked spark at that time. All good. And accelerator pump was dry. So we cracked fuel line. Fuel sprayed everywhere. Since then I have just soaked the fuel pump and lines with cold water. Starts good after that. If I shut the engine down for a minute it will start right up

In your previous thread there was an issue with bad connections and you replaced the fuse panel.

And accelerator pump was dry. So we cracked fuel line. Fuel sprayed everywhere

With accelerator pump being dry means the fuel is leaking out of the carb.
With fuel spraying all over the place when the line is cracked means the float needle is getting stuck closed. If it is getting stuck then as the boat rides along the vibration unseats it and fuel comes back in. To prove if this is the point, next time it won't start, smack the top of the carb a couple times with the plastic end of the screw driver

 

[kenny nunez]

Too bad you cannot get 100% gas . It would be interesting to see if that could help. I can still get 93 100% here in the New Orleans area. At least fuel injection is not affected by the excuse we have to put up with called "E" gas.

 

[harleyman1975]

I'm thinking carb needs a good thorough cleaning and rebuild. It sounds like it is leaking down when warm...also the clear fuel filter most likely is not kosher but if using to trouble shoot then I understand it's existence.

 

[Rinker captiva 206]

I'm thinking carb needs a good thorough cleaning and rebuild. It sounds like it is leaking down when warm...also the clear fuel filter most likely is not kosher but if using to trouble shoot then I understand it's existence.

The fuel filter I have is an Attwood made for marine use. Why are they bad?

 

[alldodge]

The fuel filter I have is an Attwood made for marine use. Why are they bad?

No clear or plastic or glass parts are allowed on an inboard or I/O, they can only be used with outboards away from the motor

 

[Rinker captiva 206]

No clear or plastic or glass parts are allowed on an inboard or I/O, they can only be used with outboards away from the motor

I did not know that... So use a marine fuel filter/ water separator? Or just a metal inline?

 

[alldodge]

I did not know that... So use a marine fuel filter/ water separator? Or just a metal inline?

Pretty much, and inline filters can be used, but they have metal fittings connection lines to them with flare or high pressure quick connects.