[Update] Dag nabbit! I think Vapor Lock is the boogy man. After weeks of trying to sort it out, and all my local car guys looking at me like I’m crazy. I have some actionable info.

I decided to buy the electric fuel pump + return line setup. Turns out the parts manual has the part to make it recycling. It’s just a pipe fitting with a 90 degree turn and a down spout into the fuel tank. The fuel tank is already fitted for it, it’s just blocked off on models that don’t use it. Great. So, as a good measure, I bought a $15 in line fuel pressure gauge, too.

I put the fuel pressure gauge on the augmented system(before installing the electric pump and return line). It reads a perfect 4.5 psi. Great thing is, it’s pressurized even with the car off. So, essentially, it records the fuel pressure that it was at when the car turned off. I drove it and hit my mystery shut-off problem. Guess what? 4.5 psi!!

All this work, and my fuel delivery is fine!

I DID notice some electrical shenanigans. The car shut off mid 3 point turn, and my blinker also cut out. Hmm? 2 minutes of sitting, and the blinker comes back on. Guess what? Car starts right up. Turns out, this is 100% repeatable. Every time the car dies like this…if you try the blinker, no luck. As soon as the blinker works, you can start the car…which happens about 1 minute later.

I’m not superstitious. And I’m also not too proud to look the fool if it helps someone else. So, I’ll admit, I jumped to the Vapor Lock band wagon…because it fit the description. Now, I’m thinking it’s electrical. You need 3 things: Air, Fuel & Spark. I assumed spark was fine, because it ran. It was getting spark SOME of the time!

Now, I looked at the wiring diagram. There’s only 8 fuses, and lots of systems share those fuses. So, it seems silly the turn signal blinker would be on the same circuit as maybe the ignition coil. But, yup. All the electrical gremlins I had seemed to be on the same line. I had fuel gauge issues. It displayed right sometimes, other times it was dead. Water temp. All these things get ignition+ on the same circuit. So, my current thinking is I got a short or bad ground somewhere that gets a little hot and kills power to my ignition coil. No way to check without having someone in my engine bay while I drive…which isn’t going to happen.

I put the electric fuel pump on the shelf and ordered a full wiring harness from AutoSparks in the UK. I’ve been putting off the rewire for a long time…living with dodgy wiring and fixing little shorts and grounds here and there. I’m sick of it. Going to do the full rewire. The kit I got has some extras, like Fog/Running lights circuits, radio circuits and auxiliary 12v dash circuits, too. So, it’s an upgrade I been meaning to do.

So, it turns out the fuel line modifications were not needed. I might revert them. Or I might keep them as a “just in case” stop for possible Vapor Lock issues later. If I had to give advice, I’d say to buy the in line fuel gauge FIRST to rule the fuel system out. It was only $15 and easy to install, and would have saved me some trouble.

Old cars, man!