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Re: difficulty starting, barely running Posted by Gary Stottler [Email]  (#1463) [Profile/Gallery]
(more from Gary Stottler) on Wed, 18 Sep 2013 19:14:13
In Reply to: Re: difficulty starting, barely running, frederickofcolorado, Tue, 17 Sep 2013 20:14:32 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Fred,
I could not see the diagram, the link only seems to lead to the 6 photos. In any event, if you have a wiring diagram that shows the circuits and wire colors for the fuel system (all the parts we've been discussing) that should let you troubleshoot those elements step-by-step. I'm not sure if I can link my documents in my Photobucket site for you or not, but I can try that this weekend (or send me an offline email and I'll just send them to you - sorry if you've already done that, I've been "on the road" since Monday).
A couple of thoughts on your project:
1) Seems like there's another Saab 99 expert/afficianado in SW Colorado, perhaps a house call can be arranged, not that I'm volunteering anyone else :-)
2)I don't think your 1976 car has a throttle switch, so you should not need to worry about that.
3)Fuel pressures are set at the factory and generally not adjustable. The pressure tests are diagnostic. First the line or system pressure (low indicates a pump problem or a restriction on the supply side between the pump and the fuel distributor, for example, a clogged fuel filter. High pressure indicates a restriction in the return line somewhere, for example, a kinked line or bad check valve). Particularly, high pressure can cause the engine to run lean, counterintuitive as it may seem. The fuel pressure gauges are needed to do this diagnosis.
4) Control pressure is produced by the Warm Up Regulator (also called the Control Pressure Regulator in official Bosch terminology)and is primarily responsible for providing a fuel mixture that is richer when the engine is cold and leaner when it is warm. One typical failure is that the Control Pressure is stuck high (equal to line pressure) and therefore the systenm is wayyyyy too lean - consistent with your symptoms). The CPR (WUR) is also set at the factory and not nominally adjustable, although I know that recently one of our intrepid East Coast members took one apart, cleaned it, reassembled it, and then used an iterative process to reset it to proper cold and warm pressures, so maybe he can detail that project for us. For about $250 a replacement CPR/WUR is available on the internet. The fuel pressure gauges are needed to sort that all out.
6) Don't worry about the CO meter unless you have to pass an emission inspection test - the idle mixture can be set "by ear" just fine - once all the other systems are working properly.
My best guess on your car is that once the wiring and base airflow items are sorted, that you will find that you have a bad CPR/WUR (stuck at "line pressure" and therefore way too lean) and/or a restricted fuel return from the fuel distributor to the tank. However, I do think you need to walk through all the basic mechanical functions of the airflow meter per my earlier note to make sure that's working and also methodically ensure that you've got no vacuum leaks.
Keep the faith, you will get it working!
Best,
Gary
posted by 108.95.2...
_______________________________________ Gary Stottler
, Fri, 13 Sep 2013 15:28:50, Sat, 14 Sep 2013 06:55:08, Mon, 16 Sep 2013 14:18:17, Wed, 18 Sep 2013 19:14:13 <-- Viewing This Message, Tue, 15 Oct 2013 18:39:45, Sun, 27 Oct 2013 11:18:09
, Fri, 13 Sep 2013 11:51:12, Fri, 13 Sep 2013 15:14:15, Fri, 13 Sep 2013 15:11:24, Mon, 16 Sep 2013 19:01:12, Mon, 23 Sep 2013 08:46:41
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