Hot day restart issues....again...

[njoconnor]

Not long after I first joined in 2012, I posted about a warm restart issue we had with our 72 carbed (stock Weber 28/36 DHSA). Didn't happen again until yesterday. We did a trip over to the local Home Depot, air temp approx 90, running time about 20 minutes, back roads, no flogging, just a nice easy drive. Parked in the sun (no choice), was in the store about 45 minutes. Came out and starter turned over fine, and we immediately could smell gas. Pat asked if I had the choke out; nope. Continued to crank, no luck. A nice guy offered to help us get a push start (by hand!), and that got us home. I've driven the car to work several times since finishing the suspension early this month, left it on a sunny parking lot all day, and not had any starting issues at all. Wondering if the combination of hot day, short drive, comparatively short parking time all contributed to a heat soak issue with the carb.

Searched last night, and about a year ago, Mark Allison posted this:

"if it happened after the car was shut off, you're probably boiling the fuel in the float bowl and flooding the engine. Common problem from a heat soak. Fiat used a phenolic gasket as a heat insulator under the carb originally"

So, under the hood with a bright light, and this is what I found:



The phenolic spacers I've seen at the various vendors don't look like that tan layer between the carb base and the manifold; it looks, to these novice eyes, to be "just" a gasket. It's also a tad under 14 mm based on eyeballing my caliper against it.

So...do I have a spacer or not? Would a spacer decrease/eliminate the hot start issue? I have the charcoal canister and the return line functional. No other symptoms when running to suggest filter issues. Thoughts?

(PS: gear reduction starter going into the car in two weeks).

Thanks

Neil

[bradartigue]

Sounds like a bad fuel pump. Mechanical? When they go bad they give up when hot.

I doubt your carb or spacer is the problem if it ran when push started. More like you let it sit long enough to get some fuel into the carb and then it caught when you started it.

[njoconnor]

Thanks, Brad. Swapping a fuel pump is one of the few things I knew about before buying the Fiat. That....and swapping clutch pedals...were the two repairs I remember on my old Coupe!

Gonna try it out again today with a much longer time out in the parking lot (and under a tree or two). I'll also start perusing the fuel pumps at the vendors....

Neil

[So Cal Mark]

you don't have a phenolic spacer, merely a gasket from the look of the pic

[njoconnor]

Mark, how much difference would the spacer make? I can see the fuel pump as a likely contributor, but the smell of gas as soon as we cranked it still suggests boiling/vaporizing fuel to me. Two more longer, higher speed runs the last 2 days (with long cooling off parked periods) have not been abe to replicate any of the issues.

Thinking maybe spacer (plus needed gaskets) and fuel pump just to cover possibilities....

Neil

[So Cal Mark]

the float bowl should be full of fuel, you don't need the fuel pump to start unless the carb is leaking and has emptied the float bowl. A weak fuel pump will show up in 3rd gear on a long hill.
If you're smelling fuel, either the accelerator pump is leaking or you don't have spark, or you've boiled the fuel from the bowl and the engine is flooded