Fuel Pump Regulator problems.

[Atocar]

Hi everyone,
I am a new owner of a 1991. 940GL. I am having problems starting when hot. I have connected and tested fuel pressure when not running. 42psi. The FPR seems to hold the pressure then doesn’t. I give it a tap and it comes good.
There seems to be many 740 FPR for sale on the internet much cheaper than a 940 one. From photos they seem identical. Is this the case??
I have ordered a new fuel filter and fuel pump as existing one runs all the time with motor going, with an annoying buzzing under passenger seat. I don’t think this is how it should sound. Using a stethoscope I can hear the pump in the tank humming, so that appears ok.
So my main question do 740 and early 940 use the same FPR.?

[Laird Scooby]

Originally Posted by Atocar

Hi everyone,
I am a new owner of a 1991. 940GL. I am having problems starting when hot. I have connected and tested fuel pressure when not running. 42psi. The FPR seems to hold the pressure then doesn’t. I give it a tap and it comes good.
There seems to be many 740 FPR for sale on the internet much cheaper than a 940 one. From photos they seem identical. Is this the case??
I have ordered a new fuel filter and fuel pump as existing one runs all the time with motor going, with an annoying buzzing under passenger seat. I don’t think this is how it should sound. Using a stethoscope I can hear the pump in the tank humming, so that appears ok.
So my main question do 740 and early 940 use the same FPR.?

Yes, usually. It sounds like the spring inside is sticking or perhaps the diaphragm is perished. Have you removed the small bore vacuum hose from it while idling (put your thumb over the end of the hose to prevent it stalling) and looked for fuel coming out of the small bore stub?

What engine have you got, B230F?

FPR for B200, 230, 234 and B204E is 0 280 160 294, FPR for B204FT is 0 280 160 730

Pg 19 of this pdf shows the above :

http://www.myvolvolibrary.info/Tech_...DataPocket.pdf

As the 740 and 940 are near identical and use similar engines, the FPRs should be the same - also you should have 43.5psi on static pressure so something isn't right on your existing FPR unless your guage is out.