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Hi, I've found some threads using search to help me, but I still have a question or two. My 86 Veloce ran fine until I parked it for an hour, then it wouldn't start. It seems that the remaining fuel in the line started the car, then it died when it ran out. Not even a cough, since. I thought she was flooded, but when I took out the plugs they were dry.

So, after looking through some good threads, I checked the voltage on the fuel pump while cranking. Volts at main pump is only 6.8V, not steady. Another observation is, when the key is switch on but not to start, the pump doesn't prime the system. If I put my hand on it, it 'kicks' momentarily, but that's it. Voltage on the pump leads with with key switched on also gives .9V.

I had to stop for dinner at this point; I still need to measure voltage across the pump leads, unbolted from the pump. My question:

If I then get 12V across the leads with pump unhooked, is the pump at fault? If not, could the starter be suddenly drawing too much, and not giving the pump enough voltage to run? The starter has been slow since I bought it, but has never failed...battery is new.

I've looked at the LJet troubleshooting page, and it seems (to me) that the drive relay may not be passing enough voltage to run the pump- is this worth looking into?

I really am getting tired of throwing new parts at a problem until I find what's wrong, so I'm holding off on buying a new main pump until I get more advice. It's hard though! I think it's the pump...what do you guys say, given what I've looked into already?

Thanks :D
 

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Volts at main pump is only 6.8V, not steady. Another observation is, when the key is switch on but not to start, the pump doesn't prime the system.
The fuel pumps only get powered on under two conditions - 1) key in 'start' position (cranking) or B) the engine is running. There is no circuit to prime the system when you turn the ignition on. (It just happens that the way the relay functions the pumps will get power for a moment when the ignition turned on.)

First thing to do is measure system voltage - best/easiest is right at the battery (i.e. don't use a dash gauge if your car has one - they are not meant for this sort of troubleshooting). Connect your voltmeter to the battery. With everything off it should read ~12.6v. Now make note of what it reads when you crank the engine. It must be above ~10.5V for the computers to power up & send the make spark/squirt fuel signals. The fuel pumps should be seeing close to system voltage under those conditions when they should be powered on. If more than 1/2 volt less then check for loose/dirty electrical connections - including in the in-line fuse holder for the fuel pumps.
 
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