Vapor Lock?

[harrisracing]

Well this is the third time the MR2 has done this to me. The more I analyze the problem the more I start thinking the car is vapor locking.

Here are the symptoms.
Fill car up with fuel (been running full since this problem) and run the car like hell. About 15-20 mins of hard running while ambient temps are high the car starts missing a bit and sputtering and I smell strong fuel vapors (can run like this for 2-3 laps) then eventually dies. It's funny because right when I start letting out of it to save the motor and pull off the car dies...and will NOT restart (couple of sputters maybe). Get towed in, wait 30 minutes and the car fires RIGHT up and runs perfectly. NO issues whatsoever with the car, compression, oil consumption, no smoking, good turbo, etc. Will make full power with no other changes other than just letting it all cool down.

Well I started reading and found that my problem could be vapor lock. Then I started thinking about the genius idea that Toyota had of routing the aluminum 1.25" diameter coolant lines from the front to back of the car DIRECTLY under the 6' long fuel tank (located in the center console of my car). Also there is an undertray that keeps all that heat up against the tank (keeps things from hitting the tank and coolant hoses).

THIS NEVER OCCURRED DURING OUR WINTER RACES so it really has something to do with high ambient temps.

I think I'm going to pull the undertray and insulate the lines from the tank. I think this would actually help with my coolant temps a little as well since 100 mph of airflow over these 12' of aluminum pipes seems like it will do something for my temps.

Anyway, just wondering if anyone thinks this could be my issue?

Thanks,

Patrick

[turbot]

Patrick, are you ever seeing the mixture reporting lean....?

Vented gas cap....? and will the cap vent enough air to not cause a vacuum for the increased fuel you are pulling now over stock...?

Have you ever released the cap to see if it'd start right up even before the 30 minute cooling period..?

Sounds like heat soak but that'd only happen after you manually shut it off after a run and tried to restart.

T

[harrisracing]

Added pictures. I think I have tried to vent trick...don't think it worked...but I will try again (something I have been thinking about as well).

Check the attached pictures for idea of what I'm talking about. This area is covered by a plastic flat panel that keeps all heat in that area.

Patrick

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[harrisracing]

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