Vapor Lock?

[NC State Guy]

Thanks to this great forum I have been able to rebuild my 1980 Searay with mercruiser 470. I have taken her out 3x for some nice test runs. I have an issue with what I believe to be vapor lock all three times.

Symptoms: Starts fine when cold, runs great, when stopped for 30 min or so, the motor will not start. No fuel is getting to the carb. Bypassed and checked water fuel separator. Checked fuel flow with a syringe from fuel pump intake, pulls very easy from tank. Disassembled fuel pump and inspected diaphragms, manually pumped lever and worked fine. Once the engine cools, I prime the lines the engine will crank fine again.

I believe the engine compartment is getting quite hot. I cannot give a specific temp as I did not have a laser therm to check today. I read that 150-160F is the norm. My gauge is still in the green when underway(although maybe it is broken) I had read some threads in here regarding a fix for vapor lock issues, but also read that the water cooled fuel lines were not advised or typically needed in the 470. I had not been running my blower except at start up. There are fresh air hoses going to the motor compartment.

There was a greenish tinge to the bilge water when drained today, maybe leaking coolant(separate issue/thread possibly). The coolant reservoir used 1/2 gallon on the last trip out. I couldn't detect a leak anywhere yet.

Sorry to be long winded.

Thanks in advance

 

[MTribe08]

Re: Vapor Lock?

What is the process you are going through to try and start it when its hot?
Read this:
http://forums.iboats.com/showthread.php?t=402612

 

[NC State Guy]

Re: Vapor Lock?

Mtribe:

I was putting a capful of fuel in the carb. After 5 or six attempts, it would finally start and run just fine.

I remember the fuel bubbling as it went into the carb though, would that indicate that the carb was getting too hot? BTW I did replace flame arrester each time before attempting start!

My thinking was that I had vapor in the fuel line and as the engine tried to crank, after several attempts, the mechanical fuel pump working off the cam finally purged the air out and brought up steady fuel flow.. My guess.

I read your thread, and will have to try the non-pumping procedure. Just open throttle a bit? I have to admit, it has been 14 yrs since I drove this boat, it had extensive repairs in the last 2 yrs. I always thought standard procedure was to pump throttle a couple times before starting.