hiya guys me again (for a change haha) my car has developed a blooming hissing sound and the fuel pump doesn't cut off on ignition prime and then the fuel smell on top because its leaking any input would be great obviously a fuel leak but have checked all clips and lines i can get too i really don't want to do a plenum pull as it looks like a scary job but at the same time i need to sort it.

Anyone who is local to myself (yeovil somerset) who has knowledge of the zed would be more than welcome to take a look with grateful thanks hahaha any ways i did a video to give an idea of where its coming from...

link..

 

thanks in advance guys :)

Anyone ??

I would guess either a fuel pressure regulator or an injector seal

well you can see the fuel pressure reg from the video and although the noise is in that area im pretty sure its not that how would i check the injectors and can this be done without plenum removal ?? cheers Ben

Sounds like air rather than fuel, the rate of the hiss, if it were fuel leaking you would see it somewhere. But getting air with the engine off is weird.

It could be that the fuel pump is pushing air rather than fuel through the pipe and cos you have a leak, that is what you are hearing, ive not heard it before, maybe jeff my sumble upon the thread and shed some light.

yeah its driving me absolutely potty to be honest and there is a definite fuel smell too i cant find any signs of a leak under the car or around the tank area so its gotta be just a problem engine end unfortunatly although my knowledge of the zed 32 is growing im not confident enough to dig right on in there and i have no local mechanic who is confident with the vg30dett either :/

So it doesnt hiss when the ignition is off? And you can hear the fuel pump prime when you switch on ignition?

Try taking the fuel cap off and see if you have any excess back pressure, also turn on ignition one youve took the cap off, it may be a pressure release issue.

Have you tried taking the vacuum hose off the fuel regulator? Is it possible that the regulator has failed inside and fuel is being pushed through into the vacuum hoses when trying to prime causing the hissing?

This might be complete b****cks BTW:eek:, but just a thought!

no it doesnt seem to hiss when i switch the ignition back off again and yes i can hear the pump constantly running ill try the removing the cap and see what happens ill update with results later :)

which hose should i remove on the pressure reg so i dont get fuel everywhere ?

Does the car start normally or is it difficult to start when cold/hot? Re your fuel pump - it should not run

continuously with the ignition switch turned to on (should just operate for ~1 second when engine not

turning). So there is a problem with the fuel pump control system.

 

http://www.300zx.co.uk/tech/manual/manual/efec/026.gif

 

http://www.300zx.co.uk/tech/manual/manual/efec/150.gif

http://www.300zx.co.uk/tech/manual/manual/efec/151.gif

thanks for all the suggestions its goven me some more ideas as to where to look ill get digging into it and let you all know with an update hopefully a positive one lol

still havent resolved this problem ive really dug deep into the engine bay to find out the hiss with no joy ... someone said that previous owner could have done a relay bypass or something anyone shed some light on this theory please ???

Does the car run? I think fried ecu's have been known to cause the fp to get stuck on prime, after all, it's that the controls the signal to the Fuel pump ecu.

 

Assuming the engine isn't running, so it's not a vac leak, in which case it's fuel related, either the reg is broken in some way or just the sound of fuel going round the system at full speed

its does it with or without the car running its obviously not running at the moment because of the waterpump being done its like it never stops priming i cant really explain it i dont know where to trace back to or from the pump to check all electrics and lines

Swap for a known good ecu first ...

 

If the car runs then unlikely to be a mechanical issue. The fuel pump controller manages the voltage to pump to switch between speeds. On all the time is most likely fault on the ecu side

ok just need to borrow an auto ecu from someone to check this then cheers buddy