Vapor lock ???

chdonley2

SCCoA Member
Road racing 1992 5 spd. 22 gal. fuel cell w/stock fuel pump in tank. Starting with a full tank, after 20 min of track time engine looses power. down to 75% of normal. Fuel pressure is normal. Return fuel line has vapor/fuel mix so we assume injectors are not getting full charge. Except for the fuel cell and cat/AC delete a stock set-up. Ran fine w/stock tank but we wanted longer stints so fuel cell. We need a solution for this. Any suggestions welcome as we are out of ideas. (Added an external fuel pump but same results so it was removed) I don't want to re-install the stock tank but that might be a last resort fix attempt.
Thanks, Chuck Donley 530-401-3189
 
Chuck:
1) Can you hook up a fuel pressure gauge to the rail and test it somewhere (track day or street since you don't live in town) to see if you are dropping pressure?
2) If you are getting less than expected fuel pressure, wouldn't that make slightly MORE power as things leaned out? To confirm if your car is leaning out or running to rich, do you have a WBO2 gauge you can hook up?

I wonder if it's a gunked filter, bad fuel pump, or an issue with an injector sticking when it gets hot. Did you reuse the same fuel pump between the stock tank and the new one?

Regards,
-g


PS. I thought you made the tbird someone elses problem and were going to race the Subaru wagon instead? :)
 
I did make the bird some one else's problem. But now I feel guilty and am trying to help him get it running up to full power all the time. Not just the first 15 minutes w/ a full tank of gas.
No I don't have a wide band sensor. Yes, I installed the original pump in the cell after an external pump first installed caused the same symptoms. so I'm thinking it's not the pump. I hooked up a fuel pressure gauge to the rail and raced around the neighborhood a while with good fuel pressure. Lots of vapor in the fuel rail when I bleed off the gauge prior to pulling it from the schrader valve.
 
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