TheSamba.com :: View topic - Help with hard start/rough running 78 FI Westy

Tue Apr 08, 2014 4:18 pm

Greetings all,

My 78 FI Westy is hard to start, and hard to keep running. I read through Bramley90's thread on his Bus' issue. http://www.thesamba.com/vw/forum/viewtopic.php?t=5...c68b1d4f3f It sounds very much like my problem. It does run somewhat better after it warms up, but definitely not the way it's suppose to. When I'm driving it'll bog and sputter, sometimes it's worse than others.

I checked the vacuum lines. Everything looks good. I tested the double relay's current supply and relay function following the Bentley instructions on page 8 of section 10. The double relay is good. Given that these two items were what solved Bramley90's problem and were suggested as first things to check I'm wondering what to troubleshoot next.

Any and all advice is greatly appreciated!

Tue Apr 08, 2014 8:44 pm

Temp sensor II controls your mixture. Easy to replace. I would start there. New fuel filter and a check of fuel pressure to cross that off the list. Is it cold enough where your at for the cold start items to operate? TTS, cold start valve, and AAR valve bypass. If u check or replace these items and your problem continues then a check of your ignection would be next. Just sounds like your not getting enough fuel caused by a faulty signal from the temp sensor.

Tue Apr 08, 2014 8:47 pm

Agreed, or a vacuum leak you just haven't found yet.

As always I have to ask, what's your fuel pressure readings?

Wed Apr 09, 2014 4:55 am

XXX/Rx/RnR wrote: Temp sensor II controls your mixture. Easy to replace. I would start there.

As I look through the Bentley I only see a temp sensor I (p. 16 section 10). Where do I find the info on temp sensor II?

Quote: Is it cold enough where your at for the cold start items to operate? TTS, cold start valve, and AAR valve bypass... Just sounds like your not getting enough fuel caused by a faulty signal from the temp sensor.

It is cold enough. In fact I bought the Bus in California and had no issues until after I drove it to Indiana. It ran fine until winter when the temperatures dropped. It has been running like crap all winter long. I assumed it would start running better when the temps got a little milder, but it hasn't. After I check out the temp sensor II I'll follow up on the these cold start items.

Thanks for the help.

Wed Apr 09, 2014 5:55 am

I have a Haynes manual. Follow your FI harness to the very end. Bundle of wires to the double relay and resisters, but there will be one black wire where the lead goes to the temp sensor II at #3 cylinder. Bout the size of a dime and screws into the head bout 3/8 inch deep. Should have a spade connector. 13mm I think. I carry a spare.

Wed Apr 09, 2014 9:46 am

Is there a test to see if it's bad?

Wed Apr 09, 2014 10:07 am

Do you own an ohm meter?

http://www.ratwell.com/technical/TempSensorII.html

Wed Apr 09, 2014 10:12 am

Temmett wrote: Is there a test to see if it's bad?

The test is given in the Bentley or Haines. With the engine hot, you can also take the wire to the sensor and ground it to the block and see if it the problem goes away.

Fri Apr 11, 2014 4:35 am

Randy in Maine wrote: Do you own an ohm meter?

http://www.ratwell.com/technical/TempSensorII.html

Yes, and thanks for the link.

Fri Apr 11, 2014 4:36 am

Wildthings wrote: Temmett wrote: Is there a test to see if it's bad?

The test is given in the Bentley or Haines...

I finally found it in the Bentley. :D

Sat Apr 12, 2014 8:38 am

I just tested the temp sensor II and it's resistance was at 3200. I'm guessing that this is a little beyond the Bentley"s "approximately 2500." I also went ahead and tested the terminals for the temp sensor I and it reads 2800. Since this exceeds 2500. The temperature is definitely not 68 degrees. I think I'll replace the temp sensor II first and see if that solves my problem.

Thanks again for the help.

Sat Apr 12, 2014 11:49 am

Temmett wrote: I just tested the temp sensor II and it's resistance was at 3200. I'm guessing that this is a little beyond the Bentley"s "approximately 2500." I also went ahead and tested the terminals for the temp sensor I and it reads 2800. Since this exceeds 2500. The temperature is definitely not 68 degrees. I think I'll replace the temp sensor II first and see if that solves my problem.

Thanks again for the help.

When the engine is at operating temperature the resistance of the TSII should only be a hundred ohms or so.