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emissions and fuel issues S70

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

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emissions and fuel issues S70

Post by DirtyDan14257 » Mon Apr 08, 2019 10:17 pm

ok guys this is a bit of a post but i really could use some help!!

i have a volvo s70 awd turbo that has been having issues with the fuel and emissions and i'm trying to solve them and make it a daily again.

this all started with a leak at the fuel pump a looong time ago, I mended the leak with new fuel line ends and called it good. the car then ran into an issue where it wouldn't fill up with fuel. when ever tried to fuel it up the thing would just kind of bubble all the fuel back out the filler hose. this issue has since resolved itself and you can fill it right up to full just fine.

the new issue or rather on going one is that the car seams to not start at all when the tank is under 6 gallons. the car still has issues starting while full but it would at-least start after a couple turns on the key or turning the starter over for a longer period of time then what should be necessary. i assumed that because the car was awd and from what i thought i knew that it was one of the fuel pumps went out and was only getting one side of the tank pumped out and that the whole reason it was having issues starting was because it was getting a weak prime.

well long story short i went out to the car and i took the "second fuel pump" out and discover that it does only have one fuel pump the other one is actually the sender unit with a couple fuel lines to draw gas from that side.

soo i went back to the parts store today and returned the extra pump i bought and bought some more fuel line ends because I'm pretty sure i botched the old ones up. i plan on getting back into it tomorrow and actually replacing the pump putting the sender back in and trying that out to see if it wants to fire right up or if its still going to act like its getting a bad prime, but what do you all think do you think i'm on tract or am i missing something obvious what would you try? i will add that once the car is running it runs just fine its just it wont start right away and it wont start at all at under 6 gallons

this post here: viewtopic.php?t=69887

is what got me to this site in the fist place and ahs alot of helpful bits on what under the car

thank in advanced to anyone who can offer insight on my issues
Last edited by matthew1 on Mon Apr 08, 2019 10:53 pm, edited 1 time in total.
Reason: Edited title. Please, no "HELP"s in titles.

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Re: emissions and fuel issues S70

Post by Sommerfeldt » Tue Apr 09, 2019 2:32 am


First off, throwing parts at these things without rigorous troubleshooting first, gets expensive really quickly. :)
Read out your error codes before you do anything else. It might not tell you anything, but it might tell you a lot.

Then, find out what kind of fuel pressure you have at the rail.
Having to crank/prime several times does point in the direction of low fuel pressure, which could be both a probem with your pump, and/or your pressure regulator. You don't mention when the filter was last changed, but it might be having issues as well.

See if you have any codes, and check fuel pressure, and then tell us what you find. We'll figure it out together. :)

- S
'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.

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Re: emissions and fuel issues S70

Post by MDK » Wed Apr 10, 2019 6:19 pm

You may have a vent issue (clogged) or fuel charcoal cannisters is plugged...maybe. MDK

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Re: emissions and fuel issues S70

Post by scot850 » Thu Apr 11, 2019 12:30 pm

The cars have only one pump as you are correct in saying (the other is an 'ejector' pump which is a name only), and it is on the RHS of the 'saddle' tank. What may be the issue is that you either have a blockage or leak which prevents the fuel being transferred from one side to the other. The LHS (drivers side) 'pump' is actually a pressure balancing unit which helps to transfer the fuel from one side to the other side where the actual pump is.

My post you have a link to should help but if you need any more info I will try to help but in the middle of 2 house renos so will check back when I get time. Either that or PM me from MVS as I will see the e-mail notification for the PM.

If you have not had the courage to drop the rear sub-frame, then if you do you may find a broken pipe in the emissions part of the system on top of the tank. There is a weird pipe with stepped rubber ends that rots out with time. It is now an N/A part. It may be hard to replicate.

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Re: emissions and fuel issues S70

Post by wizechatmgr » Fri Apr 12, 2019 9:25 pm

Check and recheck fuel pressure at the rail. Could still be a bad fuel pump...

I believe in VIDA you can get tank sensor readings for both sides individually, if you can and you see both sides majorly different from one another than you likely have the line between the tanks filled with gunk.
Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD - ~187k miles

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