What was that noise?
Thread Starter
Le Mans Master
Joined: Aug 2004
Posts: 6,886
Likes: 48
From: Glide Oregon
What was that noise?
03 Coupe Automatic
Came down a fairly steep mountain highway, mostly in 2nd and 3 gear to save the brakes. When I got to the bottom there was a pretty loud noise, similar to a hair dryer or something. I got out and walked around and it sounded like it was coming from the left rear tire well or thereabouts. It would quit a split second after I would turn the engine off. Didn't pop the hood, too late at night and no lights in the motel parking lot. Figured I would deal with it in the morning.
In the morning...no noise, no problems. Any ideas? Is there a trans cooler or something back there? Thanks.
Came down a fairly steep mountain highway, mostly in 2nd and 3 gear to save the brakes. When I got to the bottom there was a pretty loud noise, similar to a hair dryer or something. I got out and walked around and it sounded like it was coming from the left rear tire well or thereabouts. It would quit a split second after I would turn the engine off. Didn't pop the hood, too late at night and no lights in the motel parking lot. Figured I would deal with it in the morning.
In the morning...no noise, no problems. Any ideas? Is there a trans cooler or something back there? Thanks.
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
Yep, the fuel pump is located inside the left fuel tank. On the older C5 fuel systems (non-FFS), the fuel pump/sender unit is located in the side rear of the left tank, just in front of the left wheel well, and these have been known to be noisy at times. I and a friend heard another guys pump running the other day from at least 30-35 feet away.
Part way through the 2003 model year, GM totally redesigned the C5 fuel system to accommodate future LEV 2 emission requirements. Our '03 vert has the newer fuel system (with FFS) and I haven't noticed the fuel pump in it being as loud as some in the older design fuel system. One way to tell if your '03 has the newer design fuel system is to check the Service Parts Identification (RPO) Label on the inside of the glove box lid. If yours has the newer fuel system, you'll find RPO code "FFS" on this label. Also, here's a link that talks in more detail about the newer system should you care to read more. Too, this link also talks about the redesign including more isolation and noise control for the electric fuel pump:
Fuel Tank System
Too, I've noticed that the sound of many C5 fuel pumps tends to get louder as the fuel level in the left tank drops. Next time you hear the sound, see if you can determine if this is from where it is coming.
Hope this helps.
Part way through the 2003 model year, GM totally redesigned the C5 fuel system to accommodate future LEV 2 emission requirements. Our '03 vert has the newer fuel system (with FFS) and I haven't noticed the fuel pump in it being as loud as some in the older design fuel system. One way to tell if your '03 has the newer design fuel system is to check the Service Parts Identification (RPO) Label on the inside of the glove box lid. If yours has the newer fuel system, you'll find RPO code "FFS" on this label. Also, here's a link that talks in more detail about the newer system should you care to read more. Too, this link also talks about the redesign including more isolation and noise control for the electric fuel pump:
Fuel Tank System
Too, I've noticed that the sound of many C5 fuel pumps tends to get louder as the fuel level in the left tank drops. Next time you hear the sound, see if you can determine if this is from where it is coming.
Hope this helps.
Last edited by GrayC5; Oct 16, 2005 at 02:35 AM.
