Triumph Repair: spitfire running odd, vent line, needle valve

Question
Hi Jim, I have a 1974 spitfire IV everything was going good so far until this morning, My car started right up and about warmed up,and 5 mile into my drive I felt the car wanting to stall and it finally did. I pulled over the coar would not start and run unless I pull the choke. as soon as I pushed it in it wanted to satll. I check to see if I have gas I did the tank 1/2 full and the fuel filter was full. I let it sit for a 20 min. and got it started thought everything was all good and well I the way back home the car wanted to stall again I puleed the choke it kept the car running until I made it home. I live in flordia fay really came down on us hard I didn't drive the car but it did stay outside and rain ed on pretty hard. Would this affect the car it hard no problem at all before the storm. any ideas of what to look at? thanks Mark

Answer
Mark,

Having to keep the choke pulled out is a sign that there is a some form of fuel delivery issue.

Possible causes:

Bad fuel pump
blocked fuel line/dirt or corrosion in the lines
vacuum forming in the fuel tank (not really a vacuum, but negative pressure)
sticking needle valve in the carb.
incorrect timing

Couple of easy tests.

1)  Get a can of starting ether (starting fluid).  Next time the car tries to stall give it a shot of starting ether.  If it perks right up... you're not getting fuel into the cylinders.

2)  Next time it tries to stall, open the fuel cap and see if that stops the problem.  If that is it, it's possible that vapor vent line is blocked.

3)  Pull the distributor cap and clean all the contacts.  Clean or replace the spark plugs too.  

I don't think the storm did this directly, but having all that moisture under the bonnet (and condensation in the fuel tank) may have pushed a marginally working component into a non-running component.


Cheers,

Jim