Problem of the day...bloody car won't start when hot (searched the archives - useless SU HS6 on a B18). Anyway, I've spent some time trying to get the mixture set correctly following all of the recomendations etc. First it will not cold start and seemed to lean backfire (pop) then would start...so I richen the SU's a couple of flats and that seems to get better. Now it won't hot start.

I was at the parts store today (about 10 minute drive) to locate the oil seal for the OD that I need, and when I tried to restart the car (sat for 15 minutes), it would not start. I had to sit for 40 minutes and let it cool off, then it fired up and ran fine. This is getting a little embarassing. I tried to floor it when starting etc...no dice. The only thing that works is letting it cool until the temp gauge reads just below the first line by C.

I pulled the air cleaners apart and fiddled with the mixture again when I got back to the garage, but I don't think it made that much difference.

The ignition system is still stock (stock coil) and has new plugs, wires, cap, rotor, is set to 10 degrees BTDC, it is not vacuum retarded, and works fine (checked total advance with a dial back to 0 timing light - total advance right on spec). About the only thing I haven't checked is the dwell (can't recall how). The only way it likes to run is really rich.

Any brilliant thoughts? This is getting frustrating.

Craig

So this morning I reset the float level - the front carb was a little high. Then confident that my woes were over I headed off to the junk yard to pick up my Chevy truck wheels for my 15X6 conversion (cutting the centers out of the volvo rims and installing them on the truck rims). Flog the Volvo on the way out to the yard (Italian tune-up), put the wheels in the car and it won't start.

So I wait for the engine to cool off like before, and it still won't start. Now I'm stuck - but at least I'm at the junk yard. So I start to do some poking around my now cool engine. I started with the ignition, pulled the cap to discover that the rotor contact tip looks burnt out! Pull it off and the little cup falls right off - new problem (and the rotor is not yet a year old). So into the yard office and they find a rotor for me in their "whatever" pile of rotors. It's the same size (different design), they don't even charge me for it. Put it in and away I go.

Seemed to do the trick. I recheck everything when I get home and all's well. Drive the car around town - doesn't seem to be running perfectly, but it is working. And even though it is quite hot outside and I was doing stop and go driving, it started hot several times without objection. I decide to put on a new rotor just in case - swing by the parts store and pick one up.

Then things get weird - I get home with the new rotor and when I pull the cap, I found the junk yard rotor has broken (the tip has broken and the contact is about 45 degrees from its original position. I guess it wasn't quite the right size. The crazy part is that it ran in this condition!

I filed and reset the points, lubed the distributor and tried to find the missing pieces - couldn't find a thing in the distributor. I can't say I've ever had a car that is this tough - amazing.

Craig

One of the float valves may be leaking, and that can cause a very rich hot start, but if the ignition system is in good shape, it should still fire up. If the exhaust blows lots of black smoke after it eventually starts, and the engine runs very rough like the choke is on, then its flooding from one or the other float valves.
However, it does sound like weak ignition, and I would check the point gap to ensure it hasn't closed up, and be sure the condensor is a real Bosch component, and not an aftermarket one.
Rhys

Did you check the float? My (ZS) carb use to overflow and flooring the throttle doesn't do zip. Had to wait until it cooled down before making my move. Had a strong odour of gas as well. Adjusted the float, and it cured all symptoms.
--
...and the bricks keep on rolling

That sounds like the problem...I'll reset them in the morning. I get black soot just like Rhys said and GT144's description is exactly what is going on. You guys rock.

Craig.

Here's a very remote symptom that I've experienced in very hot days. If the SU's are set properly, possibly there's "vapour lock" from the fuel pump to to the carburetors. This happens often on my PV (B4B with a single Carter) especially when it's very hot outside. Cold starts present no problems. My B16 Amazon, and PV glass bowl fuel pumps, have a manual lever that I can use to force fuel into the fuel bowl and eliminate the vapour lock.

I think my fuel pumps have a weak valve that is designed to prevent fuel from being sucked back through the pump and this may contribute to the vapour lock condition.

This was a common problem with pre-electric fuel pump engines and I've heard of some people that wrapped the fuel line with insulation, or poured cold water on the line to somehow break the vapour lock.
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Cam a.k.a. CVOLVO.COM

Thanks Cam,

I'm going to reset the float levels fist and see if that helps the problem. It wasn't especially hot here yesterday 22 degrees C, but it is going up to 29 on the weekend and I was hoping to waste some time driving the Canuck. I'll put my fuel pressure gague on the pump and see what it gives me (it's only suppose to be a few PSI if memory serves).

Cheers,
Craig