280zx Fuel Pump Question

[sek8031]

So I've had this 1980 280zx for a little over a year now, and a while back the fuel pump started making a really annoyingly loud humming sound, especially after the car had been running a while. I ignored it mostly because after searching around online I read reports of other people complaining about the fuel pump being really loud and I thought it might just be normal when everything gets hot, and it was driving just fine.

Last week though, I had to drive the car to work 4 days in a row (I usually just take it out on weekends) and on the last day, noticed loss of power that got worse the more gas I tried to give it.

I took it to the shop and apparently the fuel filter is way dirty, so there's probably some gunk in the tank, and they recommend replacing the tank, fuel pump, and fuel filter. That's all fine and good if that's really what it takes to keep the issue from returning.

When the pump is making this horribly loud noise, I can turn the car off and the second I start it back up, the noise comes back. My real question is, why doesn't the pump make noise when the key is turned to the on position before the car is started? It was my understanding that the pump is supposed to come on for 20 seconds or something in that position so there would be fuel to start the engine with. Is it possible there's something bigger going on that the mechanic is missing?

[evildky]

when dealing with the older Z's corrosion in the gas tanks can be a real issue, if you pull the tank you can take it to a good radiator shop and have it cleaned and sealed for a lot less than replacing it, the filter is a no brainer, replace it! the pump is external and a pretty simple job

but yes the fuel pump should click on when the key hits the "on" postion, this is a function of the AFM, if it's not coming on then you might have a bad afm, or it could just be sticking, the test procedure is outlined in the FSM ust takes some time and a multimeter

[sek8031]

I have a copy of the '83 FSM that I found online - will the test procedure for the AFM be the same?

[evildky]

I think so, I beliee the only difference in AFM's were the turbo vs n/a