Adjustable WUR woes

[cmcclain]

I’m having trouble keeping my fuel pressure in spec on my 1980 targa (455000 miles). I made the wur adjustable a few years ago and it worked fine for a while.

Now I have to lower my fuel pressure every week. I have the wur set up correctly so the bimetallic arm does not influence the warm pressure. Triple checked the wur and epoxied the adjustable plug and diaphragm cylinder so nothing is moving.

But almost immediately after I lower the fuel pressure to spec it starts to rise. Control and residual pressure are in spec. Last time I checked control pressure it was 4.5 bar cold and 5 bar warm. Any help would be appreciated.

[cmcclain]

I must have had it set up wrong. When I adjusted so the cold pressure was not affected by the arm hot or cold, the warm pressure stopped drifting. It’s a little harder to start but runs great when it’s hot.
Next step is to go back in and adjust the cold pressure arm.

[boyt911sc]

Originally Posted by cmcclain

I’m having trouble keeping my fuel pressure in spec on my 1980 targa (455000 miles). I made the wur adjustable a few years ago and it worked fine for a while.

Now I have to lower my fuel pressure every week. I have the wur set up correctly so the bimetallic arm does not influence the warm pressure. Triple checked the wur and epoxied the adjustable plug and diaphragm cylinder so nothing is moving.

But almost immediately after I lower the fuel pressure to spec it starts to rise. Control and residual pressure are in spec. Last time I checked control pressure it was 4.5 bar cold and 5 bar warm. Any help would be appreciated.

You have flow restriction in your system. Double check these locations:

• Clogged WUR micro mesh screen.
• Flow restriction some where in the return line.

Start investigating the return fuel line section by section to locate where the restriction occurs. For the control fuel pressure to be as high as the system pressure (5 bar), the return must be totally restricted similar to closing the valve of the CIS gauge. A blockage or a clogged line is the typical culprit.

Tony

[cmcclain]

Thank you for the advice. The return fuel line is probably the culprit. I checked the micro screen and it looks good. Was thinking about replacing the return line anyway(old and cracked).

[BoxsterGT]

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