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Discussion Starter · #1 ·
Gradually working on getting my 1972 Euro market Berlina on the road. It has solex C40 DDHs and a mechanical fuel pump. The PO had it for many years off the road and only did minor work on it. I had the carbs serviced enough so it could be driven onto the transport 1 1/2 years ago. After some work I got it to start and run OK last week. Now it won't start. It will fire briefly on a good shot of ether starting flluid, so I assume I'm still getting decent enough spark and that timing didn't mysteriously change. I checked down the throats and there is no "squirt" in either carb when actuating the throttles, so I assume a fuel problem (plugs are also dry). There is fuel (with pressure) at the inlet hose from the filter and fuel in both float bowls. The needle valves work and the little filter screens are clear. I changed the fuel filter in the glass bowl and the fuel level is an inch or so up from the bottom in the glass bowl after cranking.

So, I have fuel into the carbs and in the float bowls, but it's not making it out into the engine, either through the acc pump or by engine suction. It fires on ether and it ran last week. What gives here? Any ideas? A solution that did not require two separate simultaneous failures of both carbs is more sensible, but the common elements (fuel pump, filter and lines up to the front carb) check fine, and there is fuel in both carb float bowls. It's acting as if there is no atmospheric pressure on top of the fuel in the carbs. The bowls must be vented, right? Any chance those could both be blocked? I'm tired of staring at this and could use another brain on it.
Thanks!
 

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Discussion Starter · #3 ·
Thanks for the suggestion. I forgot to mention that there is fresh gas in the tank. And it did run last week.
I also figured out how the float bowls are vented to the atmosphere: through the air box... no obstructions there.

Just to check my troubleshooting: I should get a squirt of gas into the barrels when working the accelerator, right? Neither side does.
 

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Discussion Starter · #5 · (Edited)
Does anyone have a shop manual for these specific carbs? I have an exploded diagram in one shop manual, but nothing else. Nothing turns up on the web, either. Nice to have some guidance before I go mucking around in the guts.
NEVER MIND, Brooklands is coming out with a Solex book, available MAY 1. I've pre-ordered mine!
 

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Discussion Starter · #7 · (Edited)
The PO (who imported it from Italy, worked on it some, but never made it roadworthy) evidently replaced all the rubber fuel lines. They look fresh and the hose clamps are your basic 'merican parts store versions, not original, so those seem fine. I've got fresh gas in it now, a new filter in the glass bowl (old one was nasty and there was fine sediment in the bowl. The little cylindrical screens in the carb intakes are clear. The guy who got it running enough to drive onto the transporter replaced the acc pump diaphragms and other gaskets. And it fired up and ran 3 weeks ago. But not now.
Only thing I can do is check the float levels (although hard to imagine they changed on their own in the past 3 weeks) and clean the jets (although with the filter screens clean, it's hard to believe that the jets are fouled.) But there is nothing else to do.
I'd just like to be sure that I have eliminated "the one stupid thing I missed" before I go tearing into the carbs.
 

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Discussion Starter · #9 ·
Update

Wanting a second set of eyes on this before I started surgery, I enlisted a good Alfa buddy. We repeated what I'd done, finding the same thing: fires on ether so spark, compression and timing are OK. Fuel to the carbs and filling float bowls, but no gas squirting when throttle linkage actuated. As pointed out above, this looks like problems in the carb guts being blocked.

We were able to get the engine running, but just on the "enrichment" circuit. Depressing the accelerator leaned things out and it would start to die. Shutting off the enrichment would kill it too. So gas is at least getting out to the enrichment circuit, but not to the acc pumps or main circuit. If I can get decent diagrams of the circuits, I could figure out where the blockage likely is, I guess.

So although I logically preferred a common cause of the problem, rather than two independent failures, it does seem to be two gunked up carbs, the common cause being the same fuel. I guess I managed to get the last gasp out of it a few weeks ago when I got it to start, but not again. The gas although "fresh" looked like dark yellow urine, not gas. I had removed all but a gallon or so before I put in fresh gas, but now it looks like I need to empty the tank and start from there. And it's carb renewal time. As I noted in a post above, I had the carbs rebuilt when I bought it 1 1/2 years ago, but, my bad, I then let it sit, regunking things. So I'll be on the phone in the morning to Centerline for a rebuild kit. A lesson, not expensive in parts, but in time. But, hey, now I get to learn about my carbs!
 

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Discussion Starter · #11 ·
Just remembered that Centerline does not stock Solex kits, just weber and dellorto. I think my choice is probably Highwood, unless someone has a reference to a US supplier?

Yes, I see in my cross section diagrams some ball checks. Now I just need to find that calibrated hammer... hmm all my hammers are standard, do you know the metric conversion factor from ft-lbs to newton meters?

Maybe I'll give the Gordon Raymond insitu carb soak a try, first.
 
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