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Discussion Starter · #1 ·
Hello all,

I hope to lean on all of your collective expertise.

My 1976 280z will only start if I manually stick my hand in the AFM and open the flap slightly.

Once it is running, I can make it run better or worse depending on how much I open it. As soon as I let it go it closes, and the car stalls and dies.

I don’t want to just throw parts at this car but I don’t really know what this is telling me. Hopefully someone here may have an idea of what to test next.

Thank you!!
 

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do you know if the afm has been opened up?

I have a ECU that behaves like this, so its possible the ecu is bad as well.
 

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Discussion Starter · #3 ·
do you know if the afm has been opened up?

I have a ECU that behaves like this, so its possible the ecu is bad as well.
I do not believe it have been opened up, that was my next step just to see what it looked like internally.

what exactly do you mean the ECU behaved like this? I figured that because it ran and idled as long as I was actuating the AFM, the ecu should be good.

what do you think I should test?
 

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The AFM has a miniature set of contacts that close when the AFM opens. Lets the fuel pump relay know that the engine is running. I have seen these contacts get a little dirty (oxidation) and cause issues. Cleaning them involves carefully taking the cover off of the AFM. I just polished my contacts (circled) with a paper thin piece of cardboard.

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I do not believe it have been opened up, that was my next step just to see what it looked like internally.

what exactly do you mean the ECU behaved like this? I figured that because it ran and idled as long as I was actuating the AFM, the ecu should be good.

what do you think I should test?
I have a ECU that behaves exactly like that, I can start and even throttle the car up but I need to advance the AFM vane manually (A lot) to keep it running. Just saying its possible, not likely but possible. My you tube channel shows me testing ECU's the last one is the problem. you will see it start but will not run. I did not bother to demo moving the vane manually but that will keep it running.
 

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As far as testing, I would just do what the FSM says, test everything else if it test according to the FSM, then get ECU. they come up on ebay a lot. You have to make sure you have the one that matches the years, IIRC 1978 changes, there is a big sticker on it saying don't use etc....
 

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Discussion Starter · #7 ·
Okay so I opened up the AFM, and it all looks good. I think what’s happening is that I am losing fuel pressure slightly when running, which is causing the flap to close, which is turning off the pump and killing the car.

If I give it throttle, it keeps running fine.

I am losing fuel pressure on the fuel pump side, so I am going to put an inline check valve in on Thursday and see what that provides.

Then I will go through and check the ECU.


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Try this. Unplug the starter solenoid blade and turn the key to start. Do you hear the fuel pump? If not we can narrow this down.
 

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You might try clamping down the return line on the FPR and seeing if it runs better. I was having fuel issues similar like that but a old timer to try that and see if the FPR was bad. In my case it was bad. If yours is you can get any good mechanical FPR on the market. I would recommend Aeromotives FPR and get barbed AN -6 fitting for the factory lines.
 

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Discussion Starter · #11 ·
You might try clamping down the return line on the FPR and seeing if it runs better. I was having fuel issues similar like that but a old timer to try that and see if the FPR was bad. In my case it was bad. If yours is you can get any good mechanical FPR on the market. I would recommend Aeromotives FPR and get barbed AN -6 fitting for the factory lines.
The FPR was replaced right before I bought it, but I will test this for sure. Regardless it is still losing fuel pressure going back to the pump, not at the fuel rail or FPR.
 
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