The fuel pump is switched by the airflow sensor flap in *some* L-Jet cars (e.g. GTV-6), but not, to my knowledge, in Alfa Spiders. IIRC your fuel pump is switched by the ECU based on a (crank position Hall sensor??) signal that the engine is turning. Your measurement of 9 V at the pump while cranking would seem to confirm this, but begs the question--why only 9? If that's the actual battery voltage under cranking load (as opposed to being symptomatic of bad wiring/connections/grounds to the pump), it's possible that the ECU has shut down to protect itself and isn't firing the injectors. (Again I don't know the specifics of the L-Jet Alfa Spider, but Bosch Motronic ECUs, for example, will shut down below like 10.5 V.) Try a fresh battery.
-Joe > Date: Sun, 4 Jan 2015 15:38:35 -0800 > From: "John and Deb Dohrmann" <[email protected]> > Subject: [alfa] Testing fuel pump in '86 Spider Quad > > My spider was running OK until it died at an intersection and since them > won't start, cranks fine but doesn't fire at all. Compression, fuel and > spark, right? > I read online that the fuel pump should come on if I turned the key to run > and then pushed open the air flow sensor flap. Put a remote mic on the > pump, > turned key on and opened air flow flapper, nothing from the pump. Ran a > wire > to a meter from each wire at the pump, tested against ground with key on, > flapper open, no volts. Fuse by the brain box is good, I can hear the main > relay click when I turn on the key, so makes me suspect the drive relay. > Just to be sure, I put everything back together and cranked the engine > listening to my mic on the pump - all I could hear was the starter noise. > Again, makes me suspect the drive relay. > > But just to be sure, I hooked a jumper from each side of the pump and > measured against ground while cranking the engine, now I have 9 volts to > the > pump. So the article saying that opening the air flow flapper with the key > to on will run the pump is NOT correct. And if I have voltage to the pump > but no pump whine, then it is the pump, not the relay. > > Any suggestions would be appreciated, especially how to test the fuel pump > function while in the car without cranking the engine. > > Thanks > John Dohrmann > 1986 Spider Quad -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
