Questionive got a 1985 coupe de ville, runs real good, but cuts out now and then, then it wont start for about 2 days,. i dont know if its one of the safety features, shutting off the fuel to the carb or what, when this happens, it is the fuel being shut off to the carb. tried to do the inst panel diag, but couldnt make heads or tails of it,ive changed the fuel filter, taken of the egr it seems ok but it doesnt keep constant hold with suction, it releases the diaphram, even though you keep the vaccum on it, is this a common problem or am i overlooking something, i do get an E12 on the diag. any suggestions or comments-ideas. thanks alot for your time.
jay
AnswerI don't know specifically but I have heard of problems like this on other cars.
First off, it is doubtful the EGR could ever cause that kind of a problem. The face that the valve won't hold vacuum just means the valve is bad and if you want the system to work properly you'll need a new one.
You say carburetor, I assume you're not just mixing words because some people call the throttle body the carburetor, and they are obviously similar but have very different while similar purposes.
If it is indeed carbureted, I would doubt there is any sort of fuel cutoff, that is if it has a mechanical fuel pump. It is possible but not probable that it uses an electric fuel pump, very similar to how stock cars run. If this is the case it may be possible for the ECM to disable the pump. But if it is a mechanical pump the only way I could think it coule cut off is having a solenoid and a bypass so the pressure the pump is generating could be releived without blowing the lines. But this kind of setup is doubtful and it's too complicated, I just made it up.
The only way to know FOR SURE what that code means is to search on the internet for Cadillac ECM codes, and maybe someone outer there has a listing with the proper year car and codes you need. You can also take a look in a Chilton or Haynes repair manual available at most auto shops. The have listings of all the codes for that specific car.
Since you said the EGR valve won't hold vacuum it may just be the code is the EGR code, in which case the fuel problem will be more difficult to diagnose. Bascially you will have to take a look at all the fuel lines and all the electronics involved. It PROBABLY is more of an ignition problem than a fuel problem. If it's carbureted there is not much the computer can do to cause such a problem, unless you have some sort of ignition problem.
Sorry I can't offer an exact solution, I've never experienced such problems with any cars.
