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Old 06/03/2012, 08:06 PM   #1
NosAvrenim's Avatar

Location: Burke, VA
Joined: May 10
Posts: 103

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My Garage
Fuel Filters & A Disaster Averted

Since last fall (or maybe a bit longer), the gal has been running a bit rough -- particularly at idle in gear and just after a cold start. I'd tried adjusting the carb (a Holley 650 DP) but just couldn't get it running the way I wanted it to.

After a bit of thinking and working on some other small side projects on her, it hit me that I hadn't ever changed the fuel filter since I picked her up two years ago (it's such an easy part to overlook). So I ordered replacement Holley in-carb filters and waited for them to arrive.

Well, they arrived last week and I found some time today to swap them out. I did the "exhale test" on both the new and old sets and what a difference! The front filter was clogged with small bits and I had to strain to get air to go through (the back filter wasn't much better). Needless to say, this was a major component of the rough idle and slow throttle response. I put everything back together (with my 3yr old standing beside me the whole time and taking it all in -- he's already a Mustang fan and jumps at every chance to work on her with daddy) and tested the throttle -- no issues from a cold start and she idled well once she warmed up a bit. Just a little tweaking of the carb and she's running beautifully now. Just goes to show you what an impact a dirty fuel filter really has.

As a side note (and I'm sure most of you already do this), I tested the carb and throttle from the engine compartment and found a fuel leak from the back inlet that was dumping gas onto the intake manifold. When it comes to flammable fluids, I always check (and double-check) before calling the job done. As busy as we all can get, it's tempting to short-change the testing steps and "just get it done". If you get to that point in the project, just stop and come back later -- finishing "on time" just isn't worth the potential problems. I don't want to even think about what might've (correction...most certainly would've) happened if I'd just put everything back together without testing the connections. Needless to say, I'll be checking the connections one last time before I take her out on our next drive.

Safe driving all!

Raven Black '68 GT/CS 390 X code
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