1999 S70 AWD fuel pump replacement

deano1 · Post by **deano1** » 28 Dec 2021, 17:54

Hmmm
So, original dead fuel pump is in the tank and no longer functions but fuel should still flow through it freely? So if I splice in an Inline pump after the dead pump and regulator is on the rail,, Use original wiring from dead pump to new inline pump, Right?
Makes sense in my head.
Sorry, I'm still fishing here so just throwing ideas around.
cheers

Post by **abscate** » 28 Dec 2021, 18:32

The regulator isn’t on the rail on ME7 cars post 1998. On an AWD, the pump also has to pump fuel over to the other side of the tank and draw the fuel from left side to right side. You have to make sure your solution meets all these criteria of operation

Post by **scot850** » 28 Dec 2021, 19:41

Although I know a fair amount about the AWD P80's, I'm not sure of the answer on this. There is a pressure valve on the top of the tank on the return line from the engine on the RHS. It has a pipe running from there over the back of the top of the tank to the LHS front of the tank to the ejector 'pump' and LHS tank level sensor. The pressure from this helps balance the tank levels and pushes fuel to the RHS where the main pump is. If your fuel gauge is reading ok, then you can assume for now the ejector is ok and does not need changed out as well.

I just don't know if a high pressure (adjustable) in-line pump will work or not. It would be an interesting experiment as it may help others if it works not to have to drop the tank in the future.

You need more than 50 psi on 99- cars. When Volvo checked mine it was measured at 60 psi. I would suggest not going higher than that as old pipes may not like it and there are several on the top of the tank with rubber connections.

Neil.

Post by **abscate** » 29 Dec 2021, 05:04

Here’s the detail on the crossover pipe. The thing on the right side of picture ( left of car) isn’t a pump , but that ejector contraption Neil refers to above. It’s basically a Venturi that duck fuel from left saddle to right saddle so can get the whole tank volume available

deano1 · Post by **deano1** » 29 Dec 2021, 05:56

"It would be an interesting experiment"
I don't have a dog in this fight but in the interest of other members maybe we can try some alternative medicine?
This car came to me because the garage it was at refused the work on it and PO was going to send it for scrap.
So $100. flatbed ride and now it's here with me.

I really don't want to go too deep on this because of the lack of OEM support for this car, but it is a unique model for Volvo history books.
I did pull one bolt that holds sub frame and it was white corroded bad,,Milwaukee impact handled it without issue.
And on that topic,,Does this look like it'll work? Seems awfully suspect?
https://www.amazon.ca/gp/product/B019BT ... U9UT&psc=1
Cheers

Post by **abscate** » 29 Dec 2021, 07:19

You are the Pathfinder on that. 4 years of sales and no reviews.

Here is an idea. Can you undo the torque rod bold, then undo the fuel tank straps enough to drop the tank and then to get access to pull the pump out ?

You need about a four inch drop and/or tilt from my measurement

Post by **scot850** » 29 Dec 2021, 10:42

I am sure I read a thread a few years back of someone doing what abscate suggests. It requires dropping the subframe partially to allow enough drop on the front of the tank to get the pump out. I would support the rear subframe on a jack at the center lift point on the subframe under the rear diff. Remove the shorter center bolts of the 3 on each side, loosen the rears enough to allow the subframe to pivot, and drop the fronts enough to see if the tank front will drop sufficiently.

Neil.

deano1 · Post by **deano1** » 30 Dec 2021, 07:17

Had me some extra time yesterday and did what you guys suggested.
Third picture show corroded wires that are causing the trouble.
So today's mission will be to remove pump from tank and run test see if pump is still alive.
cheers

deano1 · Post by **deano1** » 30 Dec 2021, 12:51

How do those lines come off the top of the pump assembly before i damage them irreparably?
I thought maybe the just lift off once you slide collar up like usual volvo fuel lines of this vintage but no joy yet using curved interior panel lifter.
i'll spray em down and try some more.

deano1 · Post by **deano1** » 30 Dec 2021, 19:19

Okay figured out the fuel line thing,, used this tool

and finally got it out

determined pump is still functioning but wiring simply corroded at tank entrance.
sorry about pic quality

1999 S70 AWD fuel pump replacement

Re: 1999 S70 AWD fuel pump replacement