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Discussion Starter · #1 ·
I have been working on a '77 280Z fuel injection system that will run intermittently. It seems to run out of fuel after a 40 seconds or less. I pulled the fuel line off the fuel rail after the fuel filter and placed it into a bottle, the fuel pump will begin to pump fuel when the ignition is turn to start, and stops pumping fuel when the ignition switch is in the on position. Is this normal or should it begin to pump when the switch is on position. If this incorrect would suspect the ignition switch or the fuel injection relay. Any help with this would be greatly appreciated the car was going to a driving school in Feb.
 

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For a explanation of the fuel pump saftey system:
http://www.zcar.com/forums/read.php?f=1&i=229844&t=229837

Pull the electrical plug off the cold start injector and see if it still starts, it could be that the main injectors aren't firing at all and that the engine only runs while the cold start injector is on. In that case you're battling a more serious problem.

Having the FSM (Factory Service Manual) would help the situation.

ConorP
 

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that era of z cars are equipped with fuel injection relay(s) it is mounted in the drivers side kick panel..... it has two plugs going in to it. check the connection first if you still lose fuel pump power replace . i had to replace mine before for the exact opposite reason, my cars' fuel pump wouldn't shut off. i found a good one at a wrecking yard thank god since they sell for around 100.00 + dollars
 

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Discussion Starter · #4 ·
Thanks for the information. This mess began with a hole in the boot between the throttle body and maf. I replaced the boot and had the injectors cleaned and calibrated by RC Engineering. I can get the car to run with the cold start valve pulled completely out of the manifold. When I plug the hole or replace the cold start valve the engine dies. I thought that it was the one way valve under the manifold that connects the manifold to the engine block, seems to be ok. It seems more like a vacume problem? The BMW driving school looks like a long shot.
 

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The 77 has the switch in the afm to control the pump after the engine starts so if you would get fuel when the key is turned to 'start' but if the engine doesn't start and run then the fuel pump will shut down when key returned to 'on' or 'run'. Try pushing the afm flap in a bit to actuate the fuel pump switch when checking to see if fuel keeps flowing. This is better checked with a fuel pressure gage 'T'd into the line by the fuel filter. If you remove the csv and have such a large hole in the manifold and the car runs then but dies when you plug it, it sounds like it is running MASSIVELY rich. Apparently the csv is not continuing to pump or leak when it is out of the manifold or I would think you would mention it. Since it is shutting off and running extremely rich, I would double check the connector to the AFM. I have been able to get a 78 to run with the afm disconnected but it was creating huge clouds of gasoline smoke! (it does not have the switch in afm so it could run, very richly). So you could be running on excess fuel from disconnected afm and losing fuel pump switch signal too. I would always go back to whatever was disconnected to double and triple check that I had not created a problem. If the car was running fairly ok before, and this is new, go back over all you disconnected.
 
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