gen7 dfi problem

[emtcee1973]

i have a gen 7 dfi setup in my 67 camaro, its a 383 motor. the problem i am having is after the motor is warmed up the a/f ratio meter jumps from being normal to real lean and back again and so on.the correction starts at 5% and jumps to the max of 25%..it does this at idle and sometimes while driving.what should i be looking for?? i have checked for vacum leaks and found none and i have new fuel pump installed as well..fuel pressure is good..my intake port temp reads as high as 165 degrees at idle(is that too high?)any suggestions would be appreciated..
mike

 

[norbs]

Any small exhaust leak will cause crazy readings, so I would suggest you look there 1st.

 

[emtcee1973]

thanks norbs, i checked for them and there are none..ok, i took the car out for a short run today.so i started it up and let it idle for a good half hour...got it to temp then took it out for a run...i got on it pretty good,spun the motor to about 4800rpm..first time i did that no stumble a couple of minutes later the stumble is there...so i bring it home and let it idle for a minute or two then all of a sudden the fuel pressure drops to like 25lbs..the motor starts to stumble and finally dies..now i let it cool down and start it up again i rap the throttle fuel pressure stays like a rock,after it warms up i rap the throttle again and the fuel pressure goes down when i do that..it comes right back up though..i tried three different fuel pumps and the same thing occurs..im thinking fuel pressure regulator??? what else would cause this only when the motor is warm?? also i have good voltage at the pump, about 13.5v..even when i rap the throttle the voltage stays at 13.5...the fuel pressure is supposed to go up when i stab the throttle,right?? where else should i look ??

 

[norbs]

I would say your tank vent is plugged or partially plugged, and the pump keeps trying to suck and the pressure drops after driving a for a while. Or you super heating the fuel with the pump and creating vapor lock in the system.

 

[Craig Smith]

I would say your tank vent is plugged or partially plugged, and the pump keeps trying to suck and the pressure drops after driving a for a while. Or you super heating the fuel with the pump and creating vapor lock in the system.

Agreed. Another possibility is a bad power or ground connection to the pump.

 

[emtcee1973]

so i just hooked up a tee fitting on the output side of the fuel pump under the car so i could hook a guage to it..and the needle on the guage is all over the place..is that normal? i mean does the fuel pump pulse or something?this was at idle obviously,the guage on i have hooked up on the manifold is steady though..