Deesta

Hi, I have just completed the intake refresh on my 86.5 following Scott's detailed post (thanks Scott it was terrific). Anyway everything tested well with the exception of a fuel leak in the fuel damper at the front of the engine. The fuel lines aren't leaking so I assume there must be a faulty diaphragm. Any advice on how to diagnose it further? Thanks.

Mrmerlin

spray PB blaster on the B nuts,
get a 15 mm and 19mm wrench and remove the lines,
then remove the 24mm nut holding the damper and replace it.
NOTE once a damper is leaking its best to replace all of them, both dampers and the FPR.
NOTE if the fuel lines are original its time to replace all of them in the engine bay

Deesta

I suspected as much, thanks for the advice.

dr bob

The diaphragm includes a vacuum hose that causes leaked fuel to be drawn back into the intake. If the engine has just been run, a "sniff" test of that hose right at the damper will help identify if it's leaking back. Similarly, you can test for a leaking diaphragm using a hand vacuum pump. MitiVac is a popular brand of tool. Mine suffered after it was exposed to fuel, so was replaced with a metal-barrel hand pump. Regardless of what you use, the diaphragm should easily hold vacuum for "a while". Like minutes or more, subject to leakage in the tester rather than the diaphragm. Test the fuel pressure regulator and other vacuum "clients" the same way.