308 carbs tunup operator malfunction

I have a '79 308 and just did a semi rebuild on my carbs, cleaned the jets as per Birdman's tutorial, replaced leaky acc pump diaphrams, and idle jet o-rings. I put it all back yesterday and fired it up. Mostly no problem, except that after a few minutes the car would stall. After restarting it several times, the engine warmed up and kept the idle fairly steady at about 1500 rpm. The car was running for twent-five minutes while I synched the front carbs and rear carbs. Initially, I did not reset the idle mixture screws which were set at 5 turns. At this point I shut the engine down and reset the idle mixture screws to three turns and then four turns. Now I have a problem, the engine cranks right up to 2500 rpm but when I get out of the car, it stalls out after a minute. This is similiar to the what I went through when I first fired it up but this time the engine is already warmed up.

I know it is related to the pump switch under the seat, but I don't think it is the problem, If I get in the car before the engine dies, it picks up again. Anyone know the simple answer to this? How does the fuel pump/bypass switch work so that the fuel keeps flowing when you step out of the car?

Thanks for your help.

 

Gary, thanks for your prompt reply, I could carry a sack of flour around with me too but that's not the simple answer I was looking for. This has not been a problem before and I've owned this car for 28 years. Do you know why the put the switch in in the first place?

 

I always wanted to be buried in this car anyway. Seriously, I've never had this problem and even earlier in the day it ran fine without me sitting in it. I don't dispute what you guys are suggesting, but the empirical data suggests that there's more to it.

Also, I would ask if you know if anything changed with regard to that switch. My WSM which is for a 308GT4 states that something changed after car No. 10176. My VIN starts with F106...

Thanks again for your help.

 

Actually I've lost 12 lbs.

Of course I do not disagree that it seems to be working as advertised now, but prior to my modifying the idle mixture this car has always run with or without anyone in the drivers seat for extended lengths of time. I have never thought about why it ran, it just did.

I was hoping for some clarity as to the seeming inconsistancy between the change and the resulting effect. Even if it is working correctly now I would like to know why.

If this is the way it will be, would it be unreasonable to put in an on or off overide switch instead of just strapping the circuit? Also how did you get the icons imbedded in your text?

Once again thank you for your assistance.

 

Yes, Thanks, I'll bypass the switch and insure the pump is on then finish the carb synch. Whatever was going on before, well it just doesn't seem that important at this time. The thermostatic warmup is in place but I have not validated that it is adjusted properly.

This whole project started as a clutch job, then I figured as long as the dizzys were accessable I'd tear them apart, then why not the carbs. I still have to replace a leaky valve cover gasket (the rear fortunately) and the timing belts. When I get that done I want to drive it around the block then put it back on the jack stands and install the xdi box. I,m sure I'll have more questions I hope you all have the patience for me. I've learned a lot by reading these threads.

Thanks again,