78 spider having hot start issues

[lvacordian]

Greetings,

I have a 78 spider with a Weber 32 ADFA 11 that is having hot start issues. The engine starts up normally when cold (with a few cranks) but will not start back up once the engine has been turned off and has already reached its normal operating temperature. This makes doing things like getting gas or going anywhere really difficult because I end of stranded.

I’ve tried cranking the engine over with the throttle fully opened to clear out any potential flooding and the engine still doesn’t start; in fact doing too much of this drains my battery quickly and then I have other problems. I’ve also tried cooling the mechanical fuel pump and lines with a cool cloth under the assumption there was a vapor lock issue but that didn’t help either. The only remedy I’ve found is allowing the car to sit for forty-five minutes or so.

When taking off the air cleaner I noticed a strong smell of fuel coming from the carburetor, and the primary barrel was lined with soot. Doesn’t this indicate flooding, and or backfiring through the carburetor? Other things I’ve checked out in relation to this problem are that the thermostatic air cleaner is set to correct seasonal setting, choke valve is operating properly, idle stop solenoid is working, battery’s is good, voltage regulator is operating within specifications and that the fast idle and normal idle adjustments screws are set properly. All seemed fine. All of these problems started when the colder weather started up in late November.

One other thing to mention is that the engine idles roughly and hesitates up until it reaches normal operating temperature. More specifically the engine will stall if I don’t give it enough RPM’s moving from a stopped position, and with my current hot start issue I have to be very careful. There is also some intermittent backfiring coming form the carburetor that happens only when I’m moving from a stopped position. All of this stops however once the engine reaches its normal operating temperature and then the engine runs fine, except for the hot start issue of course.

Finally my ignition module relay buzzes intermittently while driving. It sounds similar to the door/chime relay, but I know for certain that it’s not the door chime relay. I did replace the ignition module relay and it still buzzing. I suspect there is an electrical short somewhere and I’m curious if this is causing my hot start issue.

The carburetor was rebuilt over the summer and all of the internal adjustments were made to the choke mechanism. The ignition switch was also taken apart in an effort to fix my door chime relay and the idle stop solenoid was replaced.

All of my FIAT woes typically happen in the winter and I’m perplexed because I live in Southern California and it doesn’t even get that cold here, yet the cold weather seems to have a negative affect on the drivability of the car. Does anyone have any ideas? I really miss driving my spider.

[srwilson]

Interestingly enough someone just posted a simular issue just before yours.

See: http://www.fiatspider.com/f08/viewtopic.php?f=5&t=21621

You may want to read So Cal Marks comments on that tread.

[lvacordian]

Thanks for the link. In my Fiats's case the starter will crank slowly after several repeated attempts. This begins after at least 10 failed attempts. This is normal though; isn't it? The Haynes Manual mentions that the battery will "go flat” after repeated attempts. My battery miraculously seems to restore itself after hours of sitting and will crank normally on the next attempt. How would I properly test for a voltage drop between the battery and starter and what would the indication be a of a possible voltage drop?

[srwilson]

You can test for voltage drop with a standard volt meter set to measure DC voltage at somthing higher than 12V.

To measure the total drop between battery and starter you would hold one lead on the battery + post (not the clamp) and the other on the starter stud (not the cable end). Once you have the total drop you can go back and measure between the different connections to see where the biggest drop occurs, like between the battery post and the clamp (dirty post).

To take the measurement you need to try and start the car but you don't want it to start so pull the coil wire or something to keep it from starting.

Have someone turn the motor over while you take the measurement. What ever you see on the screen (if you are using a digital multimeter) is the voltage drop. Write this down. Anything more than 0.5v should be investigated for sure.

As I've said, first get the total voltage drop then go back and look individually at each point along the connection trail. You should be able to diagnose where a problem lies, if there is one, using this method.

Also check the ground side the same way.

Good Luck!!


Edit: Oh one thing I forgot, you'll either need to have extra long arms or a third person to hold one of the ends.

[md88plt]

I had issues with hot start and with engine stalling on hot days. Turned out to be a bad distributor cap. Cap was defective from new. I was able to trouble shoot issue with checking resistance of the cap contact points. Resistance went way up when cap was heated. I beleive it was a Chinese World Parts cap.