Ugh...Carb Woes? - Mercedes-Benz Forum

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post #1 of 5 (permalink) Old 02-08-2011, 03:45 PM Thread Starter
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Ugh...Carb Woes?

I have a '71 250/8 that has started giving me trouble. its got 40k on it, Ive had the car about 6 months now without any problems. I went to crank it the other day and it wouldnt start, and it turned over poorly, checked the battery out and it was old so I replaced it. Now it turns over great but wont fire. I smell fuel out of the carbs and there is gas in the tank, its at about 1/4 tank. I pulled the plugs and Im getting spark. After reading the forums a bit, apparently these carbs are notorius for being problematic. The last time I had it out there was a bit of a high idle as it would warm up, but once driven it was fine.

What could cause it not too crank all the sudden ?
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post #2 of 5 (permalink) Old 02-13-2011, 01:54 PM
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You have spark, but is it at the right time? The timing may have moved on you. Another test is to squirt a bit of starter fluid down the carb throat and see if you get some sputter of life out of the car.

If the car runs and quits with the starter fluid, you have a fuel issue. If the car doesn't even sputter or go with the starter fluid, you have a spark issue.

High idle makes me think that you have an air leak. When air leaks in between the carb and the head, it leans out your mix and idles high. Could also have some crud in the carb.
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post #3 of 5 (permalink) Old 02-13-2011, 05:58 PM Thread Starter
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ok on a whim I added another 2 gallons of fresh gas and it runs now. There was definately fuel in the tank, and the gauge indicated 1/4 tank there was def. gas in it when I parked.

Is it possible for the carbs to leak down while its parked? Like a siphon?
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post #4 of 5 (permalink) Old 02-14-2011, 08:58 AM
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Maybe a weak fuel pump, more fuel in tank eases the load on the pump,
These carbs are the best when operating correctly.
All other items must be corrected FIRST before accusing the carbs of not working correctly,
Elect tune-up and valve adjustment, compression test first.

Brian O
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post #5 of 5 (permalink) Old 02-17-2011, 03:54 AM
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Sediment in your tank can block fuel flow as well. Keep it at least 3/4 full to avoid sucking up the crud in the tank. Carb re-build kits are still available if you need them. The Classic Center in Irvine, CA can get them.
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