Mechanics

GRAND .

1993 Mercury Marquis • 100,000 miles

Have taken 2 recent trips of 500 miles. When I get to around 300 miles, the car starts bogging down and will not go over 45 mph. It will snap out of it for awhile, then bog down again. While it is doing this, it uses twice as much gas as usual. When I get diagnostic reading at the parts store, all they can tell me is it's a fuel problem but cannot find specifics. Any ideas
Avatar
Dobybears
November 4, 2011.



So the CEL does not come on? What motor is it?

Tiny
Fixitmr
Nov 5, 2011.
It's a v8

Tiny
Dobybears
Nov 5, 2011.
You need to know the fuel pressure when this happens. Also remove the o2 sensor to check for a pluged exhaust.

Cadieman
Nov 5, 2011.
So it only does this on long trips? Is it all highway (300)?

Tiny
Fixitmr
Nov 5, 2011.
Yes, it is only on long trips on the interstate. It seems to run fine in town. But after driving 300 miles non-stop when it's getting down to about 1/4 tank of gas, that's when it starts bogging down.

Tiny
Dobybears
Nov 6, 2011.
I'm thinking it could be an EGR valve issue? Or fuel pump issue?

Tiny
Fixitmr
Nov 6, 2011.