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My 83zx has been acting up lately. Every time I go above 4000rpm it skips a little and then sputters at idle for a minute. I just read that if your fuel pump is humming it is on it's last leg. Every time I turn the key on the fuel pump hums loudly. Could this be my problem? Also, my tach jumps around for a minute too. Please help!!

thankz
chadzx
 

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On 280ZXs, the fuel pump comes on when the ignition goes on, so you will always hear the fuel pump before the car starts, even if it's a real quiet one. On 280Zs, the fuel pump only comes on when the engine is cranking, so you won't always hear it until the engine is running. In either model, fuel pumps are usually audible when the car is running. As fuel pumps age (actually, usually right before they give up the ghost) they do often get louder. This is usually accompanied by symptoms like hard starting or lack of power.

So just hearing the pump going when you turn the key on your '83 does not mean it's going bad. However, if the pump is much louder than it has been in the past, imminent fuel pump failure is a possibility.
 

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I agree that simply hearing the pump is not a problem. However, you are also describing a problem with how the motor runs.

The problem you describe regarding sputtering at idle after some high rpms could be an indication the fuel pressure regulator is going. Have you checked to see if your fuel pressure is within specs?

Kevin
 

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I agree with everyone, I've also heard that many other folks have replaced a loud fuel pump because it annoyed them (but it really wasn't a problem with the pump). Several years back, one z-car mechanic in S.Cal recommended replacing the fuel pump and the fuel pressure regulator as a unit.
 

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82 - 83 Pump comes on when key is left in "run" position for 5 seconds and then the pump shuts off. The fuel pressure should be 40 PSI. When the key is turned to "start" the pump starts up again. When the key is returned to "run" the pump continues to run. If the engine stalls (no oil pressure and alternator not charging) the pump shuts off.

79 - 80 When the key is turned to "start" the pump starts. The fuel pressure should be 40 PSI. When the key is returned to "run" the pump continues to run. If the engine stalls (no oil pressure and alternator not charging) the pump shuts off.

81 ???? I have seen 3 that work like 79 - 80 and 5 that work like 82 - 83. Would someone with a 81 FSM care to quote that bible.

Wayne Monteath
Masham, Quebec.
 

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On my 78 the loud humming of the fuel pump was caused by plugged intake screen.
I cleaned it twice in two weeks then relinned the tank.
Relinning kit cost about $27 plus a qt. of asatone to clean out rust & gunk.

E me if you want more details.
 

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replace the fuel pump isolator bushings

if they are really hard or cracked. the pump vibrates alot and needs the rubber isolator bushings to stop the vibes from being transmitted to the body
 
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