Combi-relay
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"The combi-relay is the most common failure item in the L-Jetronic system. To test, unclip the airflow meter from the air filter housing. Turn the key to the “on“ position, reach inside the airflow meter, and gently push the flap open. The fuel pump should click on, accompanied by the sound of fuel rushing through the fuel rail. If this does not happen, check the fuel pump fuse. If the fuse is intact, the culprit is most likely the combi-relay. On V6’s, the combi-relay is on the firewall, and the fuel pump fuse is in the fusebox. On Spiders, the fuse and relay are under the package shelf, behind the seats." Say thank you to Centerline.
okay i'm bumping this because my spider died at a stop light and my mechanic replaced that relay and the relay near the ecu because the smaller relay was very hot. This relay though was replaced maybe 4 months ago when i couldn't get the car to start. So over the last couple weeks I've been hearing my fuel pump more often before i start the car. When i turn the key to the on position you really can hear the pump whirring and you also get a sound that sounds like fuel coming back into the tank. Now I dont hear anything when the car is in the on position. Is this normal and I just never noticed? Does the fuel pump turn on when the ecu turns on during startup? And finally do you think I have a short making the smaller relay fail so often or would the failure of the larger relay cause this?
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Normal operation is that the fuel pumps will briefly energize when you turn the key to 'on'. Then they should go silent until you turn the key to 'start'. The drive relay is supposed to get a tachymetric signal (from a sensor wire at the coil) for it to supply power to the pumps. That way the fuel pumps are only energized while the car is cranking or running.
Something sounds not right in your description about hearing the pumps run with the ignition 'on' unless you mean the engine is also running.
As far as the relays getting hot, I'd suggest checking all connections. Loose or corroded connections cause a lot of resistance which causes heat.
Something sounds not right in your description about hearing the pumps run with the ignition 'on' unless you mean the engine is also running.
As far as the relays getting hot, I'd suggest checking all connections. Loose or corroded connections cause a lot of resistance which causes heat.
Okay sounds good. I forgot one other odd thing; when the relay started to go I started to get a VERY loud electrical noise through my speakers, so much so I cant even turn the stereo on. Any ideas? Oh and my description was when the car was in the on position not running. The pump would just whir away and now it doesn't make a sound
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This is when the engine is running. In a start condition, presumably because of insufficient pulse frequency from the coil, there is another circuit that energizes the drive (fuelpump) relay. This is the start signal that originates at terminal #50 of the ignition switch (the same signal that energizes the starter) and terminates at terminal #50 on the fuelpump relay. This same start signal also powers the Thermo Time Switch (TTS), Cold Start Injector (CSS) and provides a start signal to both the fuel and ignition computers (ECUs).
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Yes indeed. I sorta glossed over that detail when I indicated the fuel pumps are energized during cranking (& running) but not by merely switching the ignition to 'on'.
Point taken Professor Neil - I will henceforth be more specific in my replies.
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