Hard cold start, perfect when warm, done all the checks, maybe ...

[sambalee]

So I've had my 79 spider for about 3 weeks now and the first thing I wanted to solve was the poor running of the engine.

It was a cheap car ($2500) and is mostly there. I bought it for the lack of rust.

The car had the original emissions setup and ADHA carb but it ran poorly with erratic idle.

So after reading around I saw that the 34 ADF is the replacement carb of choice so I bought one of the Chinese copies and installed it (after swapping the linkage lever)

The car has so far not been a great starter and in fact when cold shows virtually no signs of wanting to fire.

I did some work on the Chinese carb which was to swap the idle jet to the solenoid type from my original ADHA carb. This pretty mush eliminated the poor idle and the car runs well and pulls well on this carb now.

*However* it's a total pig to start when cold - it wasn't great with the ADHA and tended to turn over for a few times then kind of sounded like it gets "jammed" for want of a better description then carries on turning over ok.

For the last few days I've had to resort to using my mains power starter to give it a boost and it eventually starts and idles on choke just fine and warm up just fine.

Since I got it running nice when it does start I was able to set the timing to 10° BTDC (vacuum hose detached and blocked) and it really does idle perfectly when running.

I did notice that when trying to start it drains the float bowl possibly enough to cause an issue and the fuel pump doesn't seem to refill it even after a lot of cranking which surprised me.

I don't have check valves on the fuel lines in the engine compartment so more reading around reveals this to be a potential problem. I didn't have one to hand, but I did have a glass fuel filter which I installed in the hose from the pump to carburetor line. When running, the filter is nearly full, when left for several hours it still is at least half full of fuel. This leads me to think that the lack of check valves is not a big deal as there is fuel in the pump to carb hose although I've ordered some generic valves to install.

I've removed the carb top several times to check fuel level and it seems fine - although I'm not quite sure what fine is... I think it is a level that's about 35mm from the top of the lower casting for the float setting (which is about 10mm from the top of the float to the carb top underside). This seems to cover all the ports in the bowl plenty and is consistent with staining I see on two other carbs I've got indicating this is where their levels were. The point is that there appears to be enough fuel in there.

So in summary, the timing appears to be good, there's fuel, the plugs are good and clean (when running and warm, pulling each plug wire causes a noticeable change), the choke is set to close the top flap.

Is there a specific setting for the fast idle screw ? I guess so, but I have not idea what it should be - i.e. so any help here and any other thoughts appreciated. I'm going crazy, then it starts and is sweet!

thanks

Lee

[sambalee]

Also I should add that I bolted the ADF carb onto the existing ADHA manifold. Do we think that might not be pulling enough fuel in the primary to start it ? I do have an 1800 manifold which needs to go on so I suppose I should get on with that.

Lee

[124JOE]

1.5 turns out on the idle screw
be sure to push the gas pedal down twice then start when cold

[sambalee]

Thanks 124joe, to be honest I've tried all possible combinations of everything. no pumps, one pump, 10 pumps, nothing. Idle mixture is about 2 turns out and that was set when it was running nicely. Tried it with the choke off, choke on. The only thing I have left is to swap out the inlet manifold for the 1800 one - waiting on a gasket for that.

I did note today after 12 hours sat overnight that my glass filter was empty so a check valve will be useful (waiting on that), but before I attempted a start, I checked the bowl level and it had fuel and had not changed and after some cranking the glass filter was full again - implying the the bowl was getting topped up ok.

I think I heard a single "fire" and that is all today so I gave up. Just don't get this now. I might even swap back to the ADHA for a sanity check.

Lee

[RRoller123]

After it doesn't start when cold, have you pulled spark plug to see if it is wet with fuel?

[124JOE]

do you have all the vacume lines installed corectly?

[sambalee]

So everything checked out but I figured it was just super lean and simply not getting enough fuel to start.

I swapped to the 1800 manifold, no difference.

I swapped to the Chinese 34 ADFA and it solved it. I tried a few different idle jets to get the mixture screw where it should be and it now cold starts on the button.

I guess there is something wrong with my used genuine 34 ADF carb.

I'm yet to properly road test the car as I still need to do the registration process so may have to adjust the main jets etc.

Lee

[Nanonevol]

I'd be interested in hearing what jetting and emulsion tubes you've been using in both the Chinese and the genuine Weber ADF. I understand the Chinese ones have unmarked jets though so one would have to measure them to know what one had.

[Dawgme85]

A couple of thoughts, as your situation sounds similar to my experience. The partially empty fuel filter after sitting indicates that you have a leak in your fuel line somewhere. This could be due to loose hose clamps or hardened hoses, possibly cracked somewhere. On mine, it turned out to be loose inlet barbs on the carb, which I could spin and wiggle by hand. After replacing the carb top plate my cold start issue has gone away and the engine starts right up after sitting for a week or more.

Regarding the "jamming" while cranking, if it is accompanied by slow cranking (like mine was), it's probably time for a new starter. I installed a gear drive starter and couldn't be happier.

Good luck. When all is set up properly, these cars run amazingly well.

[dreavis]

I have a 77 that usually takes a few turns on the key to start if I haven't driven it for a few days+. It has a new starter and eventually does start, but it seems like it just takes a bit for it to get enough fuel to start. Once it starts I typically let it idle for a few minutes and then it drives like a new car. I always assumed that all 39 year-old cars are like this but perhaps there is something I should/could do to enable it to start the first time I turn the key. I should note that if the car hs been driven and then I drive it again later in the day, it starts first time.

If my situation is just part and parcel of owning an older car, I can live with it, but I'd really like to get some advice from others. Any comments or advice would be appreciated.
Thanks!

[brackie1]

My 77 acts exactly the same. I've checked everything I know to check read a lot of manuals talked to a lot of mechanics. No help so I'm just living with it since it runs so well once it starts for the first time.

[dreavis]

Thanks. Good to know I''m not alone. I thought I read a post in which someone mentioned a fix for this, but I couldn't find it after a lot of searching. I think post said something about fuel draining from the carb when it's not all supposed to. I honestly don't know enough to speak intelligently about it.

[dreavis]

Found the post.

http://www.fiatspider.com/f15/viewtopic ... rb#p261710