engine wants to start, but won't. - Page 2

Superman · 12-02-2002, 10:44 AM

Nope. If the rubber boot at the top of the CIS unit (the one between the throttle body and the sensor plate) is off, then your car will start and run only as long as the CSV is spraying. The six regular injectors will not spray and the car will not run longer than a couple of seconds. May be a few seconds in a really cold environment. If your car runs without that boot on, then there is something really wrong.

johnco · 12-02-2002, 11:09 AM

I'll have to tell that to my car. actually, the sensor plate was set too high after slipping off the little spring clip. but it did start and did run. right into the sawhorses and washing machine in front of the car before I got the key off. a few seconds that seemed like an hour. I wasn't actually trying to start the car, just powering up the pump and turned the key a tad too far. you can raise the sensor plate with your hand and the engine will run without the boot. I've done it many times and my car runs fine

bigchillcar · bigchillcar's Garage

Boys, boys....!

Holding up the sensor plate will manually cause the plunger in the fuel distributor to rise. This allows pressure from the bottom chambers into the top ones of the FD, thus equalizing pressure. This means that the springed diaphragm in the FD may then travel downward opening the valves leading to the fuel injectors.

Or maybe it's just because the '74 was such an awesome car! Easy killers, easy...

Ryan

Superman · 12-02-2002, 12:48 PM

Well, I think you guys understand these things at least as well as I do. That little incident with the washing machine and sawhorses perhaps was due to the cold start valve alone. Again, I think you guys know how this system works.

I've done this before too. Boot off (or some other major vacuum leak). Engine goes VROOOM die. VROOM die. VROOM die.

johnco · 12-02-2002, 01:24 PM

bigchillcar,
like you said, must be the 74. I can leave my car idling with the boot off. only when I raise the plate up too high or push it down too low, does it die. damn middle year cars! haha Then again, I had a 924 20 years ago that would start and run with 3 injectors disconnected after an engine fire burned the fuel lines. never figured that one out either.

Superman · 12-02-2002, 02:02 PM

I think you guys are pulling my chain. If the boot is removed so that the air flow sensor plate stays at rest, then there is no way the main injectors should be spraying. I'm going to have a cup of coffee now, so be careful what you say.

Tyson Schmidt · 12-02-2002, 06:27 PM

If the electrical connector is removed from the fuel pump shut-off switch, then the fuel pump will run even if the sensor plate is fully closed. So, it is possible that a car could run with the boot off, and the mixture set rich.