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Old 07-04-2005, 09:57 AM
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Tommy Tommy is offline
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Join Date: Feb 2002
Location: Dadeville, AL
Cobra Make, Engine: Sold my EM.
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Default Vapor lock at fuel pump

On a particularly hot day at the track last summer, my car started missing and the engine died. Back in the pits, I saw that no fuel was coming from the carb. I disconnected the fuel line and saw that no fuel was being pumped to the carb by the Holley Red electric pump. The pump was mounted high in the trunk and sucked fuel from a fitting in the top of the fuel cell. I put an ice bag on the pump in the trunk and after a half an hour, it started and ran normally. ... Over the winter, I replaced the fuel cell with one with a fuel pickup in a sump at the bottom. I also moved the fuel pump down to a point even with the bottom of the tank. ... Back at the track last week, the car ran great for several sessions, but during a very hot mid-afternoon session after about fifteen minutes of continuous laps (mostly 4th gear averaging about 84 MPH), the engine began to miss again. The fuel tank was half full. As the day was hot and I was tired, I parked the car and let it sit overnight to cool. Next day, in the cool of the morning, it started right up and ran strong for a full 20 minute session. Last night I drove the car two hours at normal highway speeds without any sign of a problem.

On the track, I suspect the combination of high ambient temperature and a fuel pump heated by the demand of pumping lots of gas is causing fuel in the suction line from the tank to the pump to vaporize. If that is the case, I'll need to either find a cooler running fuel pump or find a way to cool it, or both. Before I pick one or the other, have any of you experienced similar problems? If so, can anyone recommend a fuel pump that generates less heat in the fuel line?
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Last edited by Tommy; 07-04-2005 at 03:26 PM..
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