Volkswagen: 1978 VW Westfalia tarting Problem, fuel pump relay, vw westfalia

Question
Hi,

The engine start fine but stop after few second. Below is a list of different
things and I hope it will help you to give me some advice to solve the
problem.

- First, the van always run great, except for:

- When I turn on the key, the engine star for few second, then stop. I have to
do that process for 5 to 10 times and sometimes more until the engine finally
start.

- It look like it burn what it is left of gas in the engine or else then stop.

- One morning the engine start at the first time when I turn one the key.

- It happened more when the engine is cold (morning) but it did happened
when the engine is been stop for an hour or so.

- The light into the dashboard is on when the engine stop.

- When I drove for a while and I slow down for a stop, sometime the engine
Idle to fast. This append sometime not to often.

- Beside that it run very great,

Can you help me? Hope you can understand my English, french is my first
language.

Thank you for your help

Daniel Séguin
Québec, Canada

Answer
Daniel,
 From your description, I believe this is a COLD STARTING problem, not a RUNNING problem.  
One possibility is the fuel pump is not staying ON during initial startup. The way the fuel system should work:

- The key is turned to start.
- 12VDC from the key ignition is applied to the fuel pump relay (part of the double relay.)
- The fuel pump is turned ON by the relay and delivers fuel to the 4 injectors and the Cold Start relay.
- The cold start injector opens to add extra fuel during cold starts.
- The starter is turning simultaneously and the engine starts.
- The flap inside the airbox opens by air flowing because of the running engine.
- The fuel pump switch inside the airbox puts another source of 12VDC to the fuel pump relay.
- You release the key.  
- The 12VDC from the key is stopped, but the 12VDC from the airbox switch keeps the fuel pump ON as long as the engine is running.
- The Cold Start injector closes after the engine is warm (controlled by the Thermo-Time switch.)

Now the possible causes for abnormal fuel pump operation:
- The air box switch contacts are dirty or worn. (clean or replace)
- The air box flapper is sticky and opening properly. (clean and lubricate)
- The fuel pump side of the double relay has burned/oxidized contacts or bad closing coil. (replace)
- Poor connections of these. (Check and clean as required)


There are several other things which could be faulty:
- The Cold Start Injector. (Stuck closed, or the turn-on signal  from the Thermo-Time switch(ground) or the ignition key(12VDC) is bad.)
- The Aux Air Valve. (Stuck closed or the internal heater circuit is faulty)
- Temp sensor II is bad. (located on left engine cylinder head)

Let me know if you want more explanation of these circuits.

Check out this web site for more tips.  Scroll to the bottom of the page.  
http://www.type2.com/bartnik/tech1.htm

- Rick