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Some thoughts... Posted by Dana [Email]  (#2822) [Profile/Gallery]
(more from Dana) on Sun, 25 Feb 2001 11:56:24
In Reply to: Spark, no fuel when car is warm or ambient temp is > freezing, johns, Sun, 25 Feb 2001 03:15:19 Members do not see ads below this line. - Help Keep This Site Online - Signup |
85 SAAB
The fuel pump relay is a little more than just a plain relay. The overboost switch provides the main +12 VDC to the control section of the relay via fuse #22. Make sure that fuse is really good... The fuel pump relay is actually an electronic device which also monitors the ignition pulses, etc. so that it will shut down the fuel supply and injection if there is no ignition pulses to the tach. Thus when the boost switch kills the main control power to the relay...you could have weaken the internal electronic components of the relay (rapid on/off power application. The relay which when operated for a while...heat...then fail thus shutting down the fuel supply. The tach twitch during starting attempt indicates the electronic ignition module is working....
First......wait until you can not start the car. Then unplug the fuel pump relay and put a volt meter between between pin 15 and 31 of the relay socket and try to crank. If you see the 12 VDC then it is not the boost switch. Chances are good it is the fuel pump relay then....especially if you feel you have spark...you could jump the pin sockets 30 to 87 with a short piece of wire as a test...on the fuel pump relay this is the terminal which is not parallel to all the rest of the relay pin (90 degrees)you will heard the pump come on...if the car starts that's most likely it....
Your fuel pump relay socket probably looks like this...the lines indicating the spade terminal "pointing directions"
___ #87,green or green/red
#15,green | #31 | #31b | #50, yellow/red (turbo only)
| ___ | |
| #30, Brown
|
On this relay, the relay power contacts are #87 to #30 which closes to directly power the fuel pump from fuse #30. Pin #15 gets 12VDC control power from the boost switch (turbo only) via fuse #22 when you run the car. Pin #31 is connected to your car body....SO....when there is 12VDC from #15 to #31 to power the relay, power contacts #30 to #87 close to power the fuel pumps. You are only a few minutes away from telling what is going on....
, Sun, 25 Feb 2001 11:56:24 <-- Viewing This Message
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