850 acts like running out of gas!!!

David Scherrer · Post by **David Scherrer** » 30 Aug 2007, 00:17

I have replaced fuel filter, idle air injector motor unit, fuel pump. Checked all vacum lines. What could it be?
When full tank is down (from full) just 3.5 gal.(with 14 remaining) car stops as if running out of gas!
I fill it up, top it off and runs ok for a while.

What can it be.
Help

David- WA state-

volvoaddict007 · Post by **volvoaddict007** » 30 Aug 2007, 01:00

I have been working on a mysterious electrical problem titled Wierd 850 Electrical Problem and had to take a break before I continue my investigation. I have a situation that if I leave fuse #31 in the fuse block the car will run for about 13 seconds before stumbling to a halt. It feels just like running out of gas. After installing a fuel pressure gauge I realized the pressure was fine.

I had to remove the throttle cable support to get the gauge on the schraeder valve at the end of the fuel rail at the fuel injectors. To get that off, removing the multiple vaccuum line junction jiggerabob made things a lot easier. All parts facilitated w/ a 10 mm socket on an extension, after a torx bit removes the cover of course.

My initial guess is that the full tank is allowing a poorly functioning fuel tank pump to deliver the fuel to a properly functioning in line pump. There are 2 pumps in case you didn't know. Unlike many other vehicles, the in tank pump on an 850 may be removed from under the trunk floor panel ( no tank removal required

) behind the rear seats once you fold them forward. I've never removed one but a special tool may be required once you are in there but I would guess that a determined person could make something else work.

Wouldn't it be something if pulling #31 was a temporary fix for you as well ( and filling my tank would allow me to use my ECC )

Welcome to the board...

va007

mistercrunch · Post by **mistercrunch** » 30 Aug 2007, 08:12

Have you checked the fuel line relay? Someone I know had a similar problem, which was caused by this. It's located with the fuses under the bonnet, remove the 4 screw holding down the cover.

-Pieter

CarVolvo · Post by **CarVolvo** » 30 Aug 2007, 11:13

yes two relays you should check. One in the fuse panel and the other one on top of the radiator sill.