Hope someone can help.
I have a 1987 polo with a 1B Pierburg carb. It appears to not be delivering any petrol during the starting process and therefore not starting. I have benn all over it like a rash, with electrical testing and strippping it down etc, I have even swapped it with a scrap yard 1B but still no fuel.
Is the fuel supposed to drip down from the jet that comes up from the reservoir and appears out of the top of the body and hooks over the choke flap? If it is, neither of my carbs do it...I cannot fathom what pushes fuel up the jet as it appears to just dangle in the reservoir. I have blown all jets and holes through that I can see.
I have spent hours on this and it is driving my nuts, the car is only worth £100 quid but it runs lovely. I have seen other forums say that Pierburgs are pants but it used to be perfect.
Many thanks
Kilotank
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>>Is the fuel supposed to drip down from the jet that comes up from the reservoir and appears out of the top of the body and hooks over the choke flap?
No - fuel should only come out of this jet at very high engine speeds - you should see nothing from there during cranking.
Have you made sure that you have;
A camshaft that rotates during cranking (i.e., cambelt OK)
Good cylinder compressions
A good spark at the plugs?
fuel being delivered from the fuel pump to the carb?
an activated fuel cut-off solenoid (if fitted)?
*** These are the basics - check them carefully. Pierburgs are OK, the people who say they are pants just don't have the wit to understand them.
Number_Cruncher
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Yes-even the EEIT could be made to work but it was called a Solex in those days.
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I agree with Pierburgs receiving unjustified bad press. IMO this is from people who don't understand them. They are quite complex and I think yours is the 2E3 rather than 1B carb.
I would replace the fuel pump - these are cheap to buy from places such as GSF. They can develop intermittent problems, one day they are fine, the next they play up. I think they are about £30 - worth a go before you start on other things.
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Do a search on this Forum, you will find a lot of accumulated knowledge.
Whilst not your carb yo u will also find some relevance at
www.clubgti.com/forum/showthread.php?t=36156
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pmh (was peter)
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-Is the fuel supposed to drip down from the jet that comes up from the reservoir and appears out of the top of the body and hooks over the choke flap-
Accelerator pump-this shpuld give a spray of fuel when the throttle is opened sharply.
If two carbs don't work-it isn't the carb at fault,fuel pump,fuel line,fuel filter,there isn't anything else it can be.
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Thanks for all the feedback. These are the things I have done so far so hopefully it may give you some clues.
Fuel pump tested - pumps out volumes
Took whole carb off and tested suction through inlet manifold by placing paper over hole and turning engine over - plenty suck
swapped cut off solenoid (assume this is the largish solenoid at bottom of carb poitning towards cylinder head)
tested solenoid off car - works
tested wiring loom on car - works
even jammed solenoid open and reinsterted into carb
tried pouring fuel into throttle body (i know it will flood etc) - but did catch once (luck i guess) and ran perfectly if i kept reving it (assuming timing good then) - could not restart
carb sprays fuel nicely from stickyoutbit further down throttle body when accelerator pushed
one thing is wierd .... there is an electrical connector underneath inlet manifold - no idea whatit does - tested loom and ok but could this the culprit
hope you guys can keep up with the ideas ...i am desperate, and dont like to give up!!
cheers
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one thing is wierd .... there is an electrical connector underneath inlet manifold - no idea whatit does - tested loom and ok but could this the culprit
This is not weird it is the hedgehog!
My money will be on dirt in the jets. Old Polos are well known for corroding flaking fuel tanks.
Is the rubber mount on the inlet manifold sound? Does it leak air?
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pmh (was peter)
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"Is the fuel supposed to drip down from the jet that comes up from the reservoir and appears out of the top of the body and hooks over the choke flap?"
No, I don't think so.
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rubber mount - i cannot tell whether it leaks - is there a test, it is just the old one
dirt in jets - I assume that if I try blowing these again, then I could be forcing dirt harder in. Are there particular jets, holes in body that control the choke.
Should I now assume that the choke mixture emmerges from the hole beneath the throttle flap(I originally thought this was something to do with idling). If so, is there a clever way to test if fuel is getting through to there. I have tried filling the reservoir off the car and seeing if it drips in but no sign, but may be it needs suction??
thanks
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Idling mixture does come out below the throttle (and some drillings just above when your throttle is slightly open)
Fuel should not drip out of a full carburettor unless there is airflow through it (not suction!)
Once the engine is running quickly, the fuel should come out of the opening near the venturi.
Only at really high speed should fuel come out of the pipe at the top.
The will also be a jet which squirts fuel as you open the throttle.
From what you say, and the tests you have done, it sounds like the idling system is completely blocked - So,
With the ignition on, when you unplug, and plug-in the stop solenoid, does it click loudly? If not, you need to sort that out carefully and completely.
If it does click, you need to dissassemble the carb, and check the fuel route all the way from the float to the idle drillings by the throttle. You will find the fuel must pass through an idling jet, and the stop solenoid - there is also an air corrector near the top of the carb which must be free of obstruction.
By the sounds of your post, you aren't too familiar with carbs - get a haynes manual for your car (possibly from your local library?), and read up on the carburettor section - Haynes are usually quite good in this regard.
Number_Cruncher
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a meaty reply, many thanks
I will go an get a Haynes and do the things you suggest, hopefully I shall return to the forum after the weekend with triumph or tears.
...I have always found carbs and electrics a bit of a dark art!!
All contributions have been greatly welcomed
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Does the choke flap close off the the the hole in the carb to restrict the air to the engine and hence richen the mixture?
Try pressing he accelerater pedal to the floor 4 or 5 times and see if the car starts
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If you listen carefully you should be able to hear the flap 'click' shut when you press the pedal.
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I have fitted a cheap in-line transparent plastic fuel filter to more than one older (carb) motor, they really helped the slow running jets stay clear of fuel tank muck. Also WD-40 with the red spray pipe is very useful in clearing out the various jets and drillings in the carb body (watch out for spray back in your eyes). Good luck!
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