Fuel pump noise

[omegatron]

Hello All!

I've got a fuel pump that seems to increase in noise after driving....let's start at the beginning.

I live in Denver and love to go up in altitude. Last year while heepin' my fuel pump started to make a loud whine and seemed to cut out on the trail almost at tree line. While climbing a hill, the jeep died and would not re-start. I opened the fuel tank filler cap and there seemed to be a TON of pressure built up in the fuel tank. After letting the jeep rest for a minute, it started back up and I returned home.

I assumed that the fuel pump was on its way out and dropped the tank and replaced it with an Advanced Auto Parts replacement. Everything has been ok for the moment, but the fuel pump still becomes noticeably louder after driving for a few hours (regardless of the amount of fuel in the tank) and pressure still builds up when I gain altitude. The vehicle has yet to die again, but I have not gone above tree line and am a little hesitant to do so...it's a long way out to get stuck.

Here is my question...does excessive pressure in the fuel tank compromise the fuel pump? Is there some sort of relief valve that may be clogged or something I might have missed when replacing the fuel pump? In the rocky mtns its not unusual for us to double or even come close to triple the starting altitude (from 5000ft to near 14000ft); is there any special precaution I need to know about? Should I consider running an external fuel pump?

Thanks in advance for your input and I value everyone's advice.

[lafrad]

This actually sounds like a problem with your "EVAP Purge" system. sometimes called a vapor recovery system.

There are vent lines that lead to a carbon "canister" outside of the fuel tank. From there, a vacuum line goes up to the engine bay and the extra vapors are burned through the engine.

If that system was blocked, changes in altitude would pressurize the fuel tank, with no where for the fuel/air/vapors to go. this could EASILY stall the fuel pump, as it dead heads against the fuel system going up to the engine.