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Fuel Pressure Regulator leaking?


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I have discovered what appears to be a fuel leak on the fuel pressure regulator.  When you disconnect the small bore hose from the regulator, it points towards the front of the car, there is a slight weep of fuel coming from it.  Is this normal?  The hose is probably a 1/8"-3/16" dia bore. See yellow arrow on the photo pointing to the hose.

Fuel Pressure Regulator.JPG

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  • 6 months later...

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I opened up the fuel pressure regulator on my car and found the rubber diaphragm was like hard leather.  I have found out you can buy a replacement for about 15 pounds and even a new spring.  I will be replacing mine.

Just thought I'd share as this will save buying a new regulator for 55 pounds or so.


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  • 1 month later...

This weekend I replaced the diaphragm.  Photos attached of the difference.  I haven't driven the car yet, but it seems I will have to check the fuel pressure is correct.  Maybe time caused the old one to harden, or maybe the newer ethanol fuels?




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  • 2 weeks later...

I set the fuel pressure regulator per the service manual to 4-4.5psi with the ignition on but the engine not running.  I have test driven the car and it feels 'flat' on hard acceleration (I did post about this on the Lotus Esprit FB page).  The car is getting boost, well at least the boost gauge shows full boost under hard accel and I hear a whooshing nice in my right ear.  The car takes off but it seems to lack the thrust I think it had before.  Now, I have attached snippets of the service manual and I think I see a discrepancy in the notes, perhaps you can concur?  In the fuel system General Description (USA cars) section it says the fuel pressure is set to be 4-4.5 psi under light load conditions.  In the later section about the fuel pressure regulator it says to set the regulator pressure to 4-4.5 psi with the ignition on only.  Then it says run the engine and make sure the pressure is under 3.5psi.  When my engine is idling its reading about 1.5psi.  If you snap the throttle open it runs up to 4-5 psi.  So, my question is should the idling pressure be set to 4-4.5 psi or the ignition on only be set to 4-4.5 psi?



Fuel Pressure 01.JPG

Fuel Pressure 02.JPG

Fuel Pressure 03.JPG

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  • 3 years later...

Gordon:  I'm not sure if you still have this car or not, but thanks for all that great info. I have the same problem on my 85T, and NO they are not supposed to leak there. Where did you buy the part? I am going to order a whole new regulator from STJ in the U.K. and then switch out the diaphragm so I can keep the original part that says Lotus on it. Thx, Lee 

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