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i have a 76 280z that is running rich.the fuel pressure regulator make a hissing sound when the car is not running but with the key on.i was told i could check the regulator by takeing the vacum line off and see if gas came out with the key on.i tried this and no gas came out.i unhooked the cold start injector to see if it changed any thing and it did not.could the tps make it run rich like this.i put a new cap and rotor,and plugs and wires on it.the car ran good for about 5 minutes then it slowly got worse.if the regulator is bad would it run rich or lean.from what i can tell there is no gas leaking past the regulator in to the intake.the car hesitate when you give it gas but clears up at about 3000 rpms.is there any way to adjust the air/fuel mixture on these cars.could my ecu be bad.can some one give me some thing to check or try.could a weck coil make the car run bad or act like its running rich.when i pulled the new plugs out the where black.sorry to bother you about this problem again.any help would be greatly appreciated thanks


what can i say i got the car for free

thanks freez
 

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on mine, the water thermostat had a resitor in series with it. removing it made a **** fo a difference. if it was disconnected or something that would cause the symptoms you describe. if you fuel reguylator is making a hissing sound that is not good. it operates between the inbound and outbound gas lines. in this car gas circulates around constantly. the regulator ensures that the pressure is a certain amount above the intake air proesure, hence the vacuum line. if it fails, gas may or may not be leaking in the vacuum line. if gas is leaking there, then it isdefinitely gone. testing it is difficult. i would get a mechanic's opiinion, but replacing it would be my bet. i would look for other things first however, notablke tyhe water temp sensor. it is on the front of the car just under the thermostat, where the top radiotor hose comes form the engine.
 

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you need to use an inline pressure gauge on your fuel line to see if the pressure valve is good. anything over 32lbs is to much.
 

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Go to the coolant temp sensor (at the thermostat housing) and clean the connector there. Then follow the wiring from that connector back up into the wire harness about a foot. There will be 2 bullet shaped connectors there. They are likely sort of green colored right now. Take them apart, clean them and swab them with some copper grease before you reassemble. You COULD have a bad regulator but you need to check pressure with a GAGE before you go replacing the regulator. Pressure at idle s/b @ 36 psi and about 40psi at say 3000 rpm.
 

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On my '75 there is an adjuster on the air meter/throttle body covered by a
rubber plug. It is on the outside of the box and has a slot for a screw driver.
You can adjust the air flow here. Mine was running rich when I got it, soot all
over but I adjusted the air flow and all was good.
I don't recall which way to turn it but play with it, it should give you an imediate
change. All the soot will go away in a few days.
Good luck!
 

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Just for future info, all that screw adjuster does is adjust for 'idle mixture' and not running mixture. It is fine tuning to get correct mixture and CO readings at idle.
 
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