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On 13 Oct 2003 at 9:32, Cody Andresen wrote: > My 1970 Fastback has quickly developed a chronic problem with the FI. > The car was difficult getting started so I decided to take it into my > local mechanic. He was unable to figure it out. > > Up until recently, the car would start but would sound like it was > "sputtering" under load or at high RPMs. The mechanic replaced the > vacuum advance with a used one that he claimed was working. The > plugs were replaced, valves were adjusted and the timing was perfect. Make sure the dwell is correct and doesn't vary much with changes in RPM. The vacuum advance on this car doesn't even come into play when starting or most around town driving. > When the car last started (it's dead now), the engine would stall if > the car came under to0 heavy of a load (ie. I would give the engine > too much gas). I was driving in the city, no hills, to avoid a > stall. When the car did stall, I had a heck of a time getting it > started and had to play with the accelerator, got it started when I > had it fully depressed. Sounds like a good time to check the fuel pressure. It might be as simple as a clogged fuel filter. Does your car leak gas below the fuel filler if you top the tank all the way up? > The mechanic I took it to for a second opinion wants to do a carb > conversion. I'm not convinced this is the best alternative. I've > taken matters into my own hands and have been reading up in my > Bentley. I'm also armed with my volt meter from Radio Shack. Good, your mechanic is just trying to take a short cut out of this dilemma, because he doesn't understand your system, he doesn't want to spend any time learning about it, and he isn't paying the bills. > For a newbie who wants to do some diagnostics on this type of FI, is > there a good method of deduction that I should follow (besides what > I've read in the Bently manual)? I just want to avoid stupid > mistakes and not fry any of the electronics. It is very unlikely that you'll fry anything in the FI. Start with the basics. Do you have fuel under pressure? Is the brain getting power? Do you hear 2 relay clicks when you turn the key ON? Do you hear a series of clicks from the injectors when you turn the key on and depress the throttle (you have to be back at the engine to hear these.) Each of these tests verifys a different part of the system. Personally, I'd check the fuel pressure first, or ask your mechanic if he checked it. It should be about 30 psi. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org