Fuel system issue when hot

[Whizbang]

Regarding my 82 Rally Rx7. She is rather modified, but the issue seems like something i "engineered"

So twice now, as I type stranded at work, I have had issues with the car starting and idling at extreme lean (17:1 and higher) AFR readings and basically being undriveable from how lean the car with throttle is applied.

This has happen only on very hot days, while the car was sitting in the sun. The last time the car ran fine after it cooled down. Ideally it should this time too.

Some things:

• opening the fuel cap did nothing
• running the fuel pumps, seperate or simulantously did nothing
• or running them for any length of time (minutes)
• getting the car to temp did nothing

also the pumps don't "sound" right either. This is all on a stock FB tank, feed to pumps into the spare tire (above tank). Return on the stock FB tank should suffice. Or at least not cause a LACK of fuel.

anyway, i want to burn this fucker to the ground.

[GySgtFrank]

Which pumps are you using? The 1.6 is injected, correct? Have you checked the fuel pressure getting to the rails?

[Whizbang]

Originally Posted by GySgtFrank

Which pumps are you using? The 1.6 is injected, correct? Have you checked the fuel pressure getting to the rails?

Walbro 255lph, two in parallel, so they be ran individual if one fails on stage. Fuel pressure is good. After it cooled down, it worked fine again.

the issue im finding is that the heat through the hatch is baking the pumps under the bulkhead (they are in the spare tire well, with an Al bulkhead per rules). When the pumps get hot enough the fuel is vaporizing. You can hear them whine without any good load. Once the car is cool, the pumps loaded up and sound much different.

so either i need to install a lift pump, or somehow compensate for the fact the pumps are above the tank. Stupid poorly located fuel tanks.... wish i could use a fuel cell...