I don't think this will work

[slowmo]

Good idea. I'll report back.

[chuckstp]

Just one thought for those who put in an electrical fuel pump. I don't know how they mount, but if it were possible to mount it farther aft closer to the fuel tank, that may alleviate your problem. I heard one person talk about installing a heat shield, but he never included an update. I'm going to see what the feasibility is for installing one on mine.

I had already gone through the gas cap trick, and the first time I tried it, it seemed to work. I think it was just the additional time and movement of gasoline because it hasn't prevented it since then.

[slowmo]

Checked the fuel cap and I did not detect a vacuum. The next day I replaced the fuel pump and problem solved. The old one was apparently...old. I also got the water temperature gauge to function AND the horn now honks. Three, count them THREE issues solved without a single scraped knuckle. The list is getting shorter.

[MJL]

I haven't had much time to investigate my initial issue but I did get an opportunity to do some stuff yesterday. I recreated the cutting out shortly after a hot start. I checked for spark and all looked good - so back to the fuel delivery.

O2batsea suggested I may have a sticking needle valve so I carefully poured some water over the top part of the carb close to the fuel entry hose. This cooled the carb down and the car immediately restarted.

This morning I removed the top part of the carb to check the valve (which of course showed no sign of sticking when cold !). The needle valve is one with the rubber tip but I have a new all brass one from a rebuild kit I've had lying round for a while so I thought I'd give that a try. Unfortunately the gasket between the 2 halves of the carb broke when I took it off and I didn't have a new one of those. I do however have a spare (old) zenith carb which didn't work properly last time I checked (years ago) so I removed the gasket from it.

Herein lies my question - when the emulsion block was removed from both carbs to get the gaskets off I noticed that on the carb just removed from the car that there was no ventilation screw installed, but there was one on the old carb. Should there be one? Should I just install the one from the old carb?

There is a discussion of the purpose of this screw in the zenith carb service manual. Is states that by variation to the ventilation screw it is possible to alter the mixture ratio between low and high speeds at part and full throttle.

Is it possible that the ventilation screw is not used in zenith carbs when used in LR's? I've been using this carb for years without it with seemingly no detrimental effects. I bought the carb as a rebuild replacement from our hosts - so that is the way it was delivered!

So what is the recommendation? Rebuild the carb with the ventilation screw from the old zenith (not necessarily a carb from a LR) or leave it out?

Mike

[MJL]

Here's want I ended up doing. The green bible clearly references the ventilation screw so I decided to use it. I rebuilt the top end of the carb using the emulsion block, gasket and top cover, I installed a new idle mixture screw and economy diaphragm (just because I had one) - I transferred the jets and float from the original carb put it altogether and installed it. I was amazed - it started right up and when warm just needed a minor tweaking of the idle speed screw.

However when I let it sit for a while and started it up it behaved exactly as before, it would start and run roughly for a few minutes, popping through the exhaust and finally cut out and wouldn't restart. I had a new coil so I thought what the heck - let's try it. Put it in repeated the sequence and it still behaves exactly as before.

As soon as I cool down the carb by pouring water over it, it will start right up and seems to run smoothly.

Any thoughts? Could it be the float, I did reuse that. Could it be the rubber ring around the throat in the base of the carb? I looked OK but is the only component in the base I could think might be the problem.

Very frustrating

[chuckstp]

In my case, after being hot and sitting idle for some time, the car starts right up. It is after driving it a few dozen yards, it sputters and dies. I did come up with one solution which seems to have worked so far although I haven't tried it enough to call it conclusive. Keeping with the KISS principle, this takes no additional parts or basic modifications of the vehicle.

The technique is slightly different whether the vehicle is a left hand drive or right hand drive. For the left hand drive, lift the hood and leave it up during the idle period. If you happen to have a right hand drive, you would want to leave the bonnet up instead.

The hope or thought is, some of the excess heat is allowed to dissipate allowing the carburetor and fuel pump to stay a few degrees cooler. Like I said, I haven't done enough times to make a solid claim, but it can't hurt.