AutoBanter - View Single Post - 84 VW Rabbit GTI

**Jim Behning[_1_]** · September 12th 06, 01:49 AM posted to rec.autos.makers.vw.watercooled

Bad cpr will cause a loss of residual pressure.

On 10 Sep 2006 20:02:27 -0700, wrote:

>The post alluding to vapor lock is probably correct. The CIS system is
>very sensitive to having sufficient residual pressure in the system
>when the vehicle is hot. Often the cuprit is the check valve at the
>fuel pump. If the smallest speck of rust gets caught in the check
>valve it will not close, and the fuel will return to the tank, ergo a
>loss of pressure. Often this can be heard, when the engine is turned
>off, it sounds like a series of pings coming from the area of the gas
>tank outet. It sometimes is immediate and other times very slow
>depending on the size of the speck of rust or debris.
> One can check this by loosening one of the bolts that seure the
>banjo fittings to the fuel filter --- if the check valve is faulty,
>there will not be a sudden release of pressure. if the check valve is
>ok you will get a spray of gas. One should be careful in doing this as
>one can get a facefull of pressurised gas if the check valve is ok.
> On my 81,82, and 83 rabbits there is a hot start pulse relay that
>is not integrated into the fuse panel --- it is in its own separate
>holder, usually affixed to the fuse box by tape or a tie fastener -- i
>have also seen them merely stuffed behind the box or dangling loose.
>Since i do not have a 84, i'm not sure where its located, but when
>functioning property, it causes fuel to be injected on an intermittant
>basis in very short squirts during the initial cranking. Its called a
>hot start pulse relay and Bentley shows its location on page 49 of
>section 4, above the fuse box and say it is identified by its three
>terminals and part no 813 906 064. Every post 1980 rabbit has the
>relay.