7.4L MPI Stray Vaccuum Line

jayws6 · 05-30-2013, 04:20 PM

Hi guys,

Was installing new bilge blowers last night and noticed a Vaccuum Line that originates from the front of the engine, to the right of the flame arrestor, tees into a small diaphram and the intake manifold, has the other end open. I'm not sure where the other end is supposed to go. Any ideas? Hope I was clear enough in describing it's location.

Thanks!

Jason

Andy b · 05-30-2013, 05:46 PM

A picture is worth a thousand words

jayws6 · 05-30-2013, 05:53 PM

There is only one line off the front of the engine. Figured those with the same engine may be able shed some light. I can grab a pic this evening.

Thanks

Jason

***Hudson River Steve*** · 05-31-2013, 01:07 PM

Jason,
On my 1999 7.4 MPI, there is only one vacuum T. Obviously the T is fed from the intake manifold. The T branches off to the fuel pressure regulator on the "Cool Fuel Assembly" at the bottom of the engine on the port side. The other side of the T goes to a Fuel Pressure Damper which is mounted on the fuel rail on top of the engine. From your description it sounds like the errant vacuum line goes to the fuel pressure regulator.
Hope this helps.

jayws6 · 06-07-2013, 02:44 AM

Hey Steve,

You got it!! I looked to the fuel cooler and sure enough, there was a vacuum line left open that I was able to plug the intake line into. Thanks very much for your help! Hopefully the previous owner didn't have it left open for a reason....

Jason