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1600 starts&stalls on first try, then starts and runs fi


bmw_jeff
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I went through the archives but did not find this same issue. My early 1600 is using the original but fully rebuilt Solex with manual choke, Motor has 166k on the original block and compression was low but even, about 110-120 each but not sure the gauge is good.

I pull the choke out all the way, pump the pedal 3 times to prime. Every time I start it cold, morning or after work, it fires right away, runs for a couple seconds, then stalls like I turned the key off. No matter how much the choke is out or how much I rev the gas. It doesn't sputter or anything, just shuts off.

On the second try it cranks a few times, then fires hesitantly and runs OK from then on with me modulating the choke until its warm. No stalling or idle problems at all beyond that startup issue. It almost never stays running more than 3-5 seconds on the first try. Could it be a low compression thing? All my electrical is new(er) and in top shape. Points/dwell etc is spot on. Thanks in advance.

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It sounds like your float bowl is draining out. Next time you try to start it, take the aircleaner cover of and move the throttle linkage. You should see a squirt of gasoline going into the carb. When it stalls, turn off the ignition and try to squirt again. If no fuel is present it means your float bowl is empty. G

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bowl is emptying. This is unusual for the 1 bbl Solex--they will usually hold fuel for several weeks--much better than the later Solexes or Webers. Thus, something is the matter.

In addition to Gracer's suggestion, try this additional test before you attempt a cold start. Pull the top off the air cleaner and you'll see a small brass tube stickiing up through a rubber grommet on the bottom of the air cleaner can. That's the float bowl vent. Pour a small amount of gas down that vent--no more than a couple of tablespoons--to fill the float chamber. If that prevents the engine from stalling after initial startup, then it'll confirm a dry float bowl.

What's happening now is that you're starting on the gas that's in the accelerator pump circuit; once it's gone, the empty float chamber won't supply gas until the (mechanical) fuel pump fills it up again.

Let us know whatcha find...

mike

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Thanks guys. c.d. - the hoses are new and the pump was just rebuilt, but it had this problem with the old pump too. I think you all may be right on the float bowl, it does run dry when the car sits for a while and I have to add gas manually from the top to start the car. I had the carb professionally rebuilt with a NOS BMW repair kit (did not incl float parts though) and they also tanked and cleaned everthing so it looks new. Fuel squirts normally when I depress the throttle linkage. The question is, why does it run dry and how do I fix it?

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  • 5 months later...
Jeff, or others did you ever figure how to fix this? My 1600 does the exact samething when cold.

Well my main problem is that the float bowl is emptying partially while the car sits, even for a short time. No evidence of leaks on the outside, so it must be leaking inside the chamber and down into the engine. This I have not attempted to locate or repair yet. I have no idea if it can even be repaired.

The second "problem" was that when I got the car I added the typical in-line fuel filter 02's use. Well my '67 car never had one from the factory and the PO never added one for 36 years of ownership. My mechanical pump, even being rebuilt, was evidently having trouble pulling up the gas through the big air gap created by the filter without alot of cranking. After I recently removed the filter so it was abck to original configuration, I can now start the car on the second try most of the time, without having to manually add gas. I guess without the filter in the way the pump is able to prime the bowl on that first failing start attempt, so it can start and run the second time.

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