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shortcake

VW Enthusiast
Registered: 08/23/04
Posts: 17
Reply with quote  #1 
Hello, I am Shortcake's father and I have just rebuilt and reinstalled the engine (1600 CC fuel injected) in her 1975 Super Beetle.  The engine has new pistons, rings, cylinders, bearings, lifters (cam followers), gasket set, spark plugs and wires, and remanufactured air flow sensor.  The crank was turned and the case was line bored.  The car will start but will only run for a few seconds and then stalls.  If the engine is revved a little it will run for a few more seconds but starts to die as soon as you let off the gas and sometimes will not rev up again when gas is applied.  The car does start on every attempt but stalls every time.  I have set the timing statically (making sure I was on #1 cylinder), checked and corrected as necessary any loose air and vacuum lines, checked the injectors for fuel flow, checked the condition of the coil, checked and rechecked the firing order, and made sure that I had a solid ground connection.  The intake manifold is secure at the head and the intake to air distributor hoses appear to be tight.  I have cleaned but not replaced the distributor cap or rotor, and have not replaced the condenser, fuel filter or pump.  There is oil pressure.  The engine was running prior to the rebuild.

Any suggestions as to what the problem may be.  This is my first VW engine rebuild and I have run out of ideas.

Shortcake's father.

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1975 SB - green - stock
68autobug

VW Guru
Registered: 02/20/04
Posts: 1,907
Reply with quote  #2 
Only thing I can think of, is the fuel filter or condenser....
Both can cause intermittant problems...
I don't know anything about fuel injection as it was never used on Beetles in Australia.. so I don't know how the fuel system works...
 
I hope its something simple...
well, it can't be internal, as the engine does run and start OK....
it sounds quite strange to start every time but won't continue to run....
No loose wires etc.... it has to be something simple.... the engine is getting air all the time, it isn't being cut off..?
Fuel, Spark and air....  One of these? it has to be...When the engine stops check that there is still power to the coil etc..
Wish I could help more..
 
Lee Noonan  -- 68autobug -- Australia --
 
http://community.webshots.com/user/vw68autobug

 

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Marc

VW Brainiac
Registered: 10/19/04
Posts: 183
Reply with quote  #3 
Try removing the air filter and shoving a long thin screwdriver or something into the airflow meter so the flap can't return to the fully-shut position. I'm betting that your problem is caused by it doing so, which shuts off the fuel pump (if you aren't cranking the starter).
If the car now runs, your next mission is to find out why the flap is closing - the engine must be drawing in unmetered air somewhere downstream of the AFM.
If it still dies, you should check the double relay to make sure it's supplying power to the pump with the flap open. Bentley manual shows the pinout and how to check with a test lamp.

You didn't mention it smelling rich; if it does, the cold-start valve may be leaking or something may be telling it to squirt when it shouldn't (like incorrect wiring at the thermo-time switch). If you suspect that sort of problem try pinching off the fuel line to the cold-start valve.
shortcake

VW Enthusiast
Registered: 08/23/04
Posts: 17
Reply with quote  #4 
Thanks to Lee and Marc for responding.

I have checked the wiring and the hoses (I did not do the ether or propane test).  When the car stops there is voltage at the coil.

I propped open the air flow meter flap and the car did stay running, although it was a very rough idle.  If, as Marc states, there is an air leak downstream from the AFM, what is the best way to test for the leak?  Using ether or propane or similar gases is not my first choice as I am working in my garage (it is -10 degrees centigrade outside and getting colder tomorrow).

Once that problem is solved I will need to solve the rough idle problem.  But first things first.



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1975 SB - green - stock
Marc

VW Brainiac
Registered: 10/19/04
Posts: 183
Reply with quote  #5 
The flap's open further than normal at idle which'll cause rich running, that may be a large part of the roughness - but at least it runs so now you should be able to find the leak by squirting a non-volatile fluid at suspect points (carb cleaner, WD-40, whatever you have handy - even water will do).
You might also want to try pulling the plug wires out of the cap one at a time to see if you've got one or two cylinders that aren't with the program - perhaps bad injector(s) or broken wiring at the serial resistor block.
veedo

VW Enthusiast
Registered: 05/16/04
Posts: 49
Reply with quote  #6 
really sounds like a vacuum leak---try checking for splits in the ribs of the intake boot. The safest way to check for leaks is with a smoke machine. It is hooked to the intake and fill the intake system with smoke and it will come out where ever there is a leak. If you dont't have that carb cleaner works pretty well--spray on suspected areas and listen for rpm change. really check all hoses carefully----if they are original they can split and crack. I have seen the oil filler crack from cold temps and cause idle problems as well as a cracked oil cap. These are plastic items. good luck
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57 vert, 67 vert, 75 german look monster.
shortcake

VW Enthusiast
Registered: 08/23/04
Posts: 17
Reply with quote  #7 
I found one leak in the hose at the auxiliary air regulator which I fixed, or at least appear to have fixed.  However, that has not resolved the problem as I still have to prop open the air flap on the air flow meter to get the engine to run.  Unfortunately I have run out of time to work on the car so I will be taking it to a VW mechanic to see what he can do.

I want to thank Lee, Marc and Veedo for their assistance.  It was much appreciated.  Here is wishing you all the best in the new year.

__________________
1975 SB - green - stock
shortcake

VW Enthusiast
Registered: 08/23/04
Posts: 17
Reply with quote  #8 
I am finally getting back to working on my daughter's car.  I had the car inspected by a mechanic and was informed that they found a couple of leaks.  The intake manifold coupling sleeves (boots) are leaking and the area where the throttle linkage shaft enters the throttle body is also leaking (hole has worn).  These will need to fixed.
The other problem that was mentioned was that the distributor was wearing out to the point where the dwell angle could not be set properly.  It was therefore suggested that the distributor be replaced with a Bosch 009 and the two vacuum lines that go to the stock distributor be plugged at the air intake distributor.  In discussions with another individual, I was told that the Bosch 009 can not be (should not be) used on the fuel injected engine and that I should use a SVDA distributor.  Has anyone changed the distributor on a fuel injected engine and if so what is the best one to use?

Doug

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1975 SB - green - stock
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