I have a 98 s70 volvo with 133K miles on it. Recently while driving it seems to lose power: e.g. RPMs would just go down from 2.5 to 1 and lower and the car would stop accelerating. After a few seconds (20-30) it would pick up again and might exhibit the same behavior right away or might just drive fine for a while.

First I thought it’s the dirty air filter and possibly spark plugs. Replace both 2 weekends ago and the car was ok for city driving. Then I took it on a long freeway ride, and on a way back the this symptoms stared reoccurring. It lost power 2 or 3 times like that and on the 4th time it decided to stall. Had enough momentum to get the car off the freeway, but power and power steering was totally dead.

Once on the side of the road the car started fine, but I decided it would be safer for all to tow it. Any idea what usually causes this intermittent power loss?

Thank you,

Henry

 

did the check engine light come on? Have you scanned it for any codes? That would help diagnose it.

 

Sorry, should have mentioned this: no engine light, no error codes.
The guy who towed me said it might be a fuel pump or some circuit. Any ideas?

 

Symptoms sure sound like either the fuel pump relay or the fuel pump itself is dying. Lots of good threads here on how to diagnose; google is your friend.

I just tried; think this site is updating their DB or something; will try again later.

 

ETM failure. kinda sorta. No lights doesn't mean there's not a code.

Fuel pump relay failures usually happen on hot starts (heat messing with resistance properties). Fuel pumps usually just go out all together, very rarely do they gradually "loose pressure" ither pressures there or its not.

 

See post #8 in this thread:
https://volvoforums.com/forum/volvo-...estions-55124/

Lots of good links there for diagnosing fuel related issues; if it's not that then you will eliminated that as possible cause of your problem.

 

Could it be a fuel filter? I don't think it has been changed in a while. Would it be able to cause this behaviour?

 

I doubt it's that filter. People go many years and miles without EVER replacing their fuel filter. They are due changes every 100,000 miles. It would not be intermittant.

When I had a fuel relay problem it was very random. I'd be driving down the street and wham, the wind (or fuel) would just go out of the car like someone pulled the plug on the thing. It would spudder for a few seconds and sometimes die, sometimes catch and drive on. Sometimes it wouldn't start, sometimes start and drive for 150 miles. The relay is somewhat of a cheap fix. I think I'm just going to change mine every 10 years.

 

Based on your comment it might be a fuel relay. From what I heard, the pump usually starts emitting a high pitch noise, but I don't hear it - only some noise on cold engine when I turn a wheel, but then the noise disapears (so that should be a different problem). Do you by any chance know where they are located on S70 (I don't think my manual lists it, or not under fiel relay) and how expensive are they? Is it easy to install, or do you need special tools and special equipment?

Thank you,

Henry

 

Found these two links:
https://volvoforums.com/forum/volvo-...p-relay-61442/
and Compression Test - Volvo S70 GLT, 1998 which are useful. Will check my car this weekend.

 

That 2nd link if from my repair site. I think they cost about $60. As I said before, I think they should be changed every 10 years. I also believe they cause fuel pumps to go out because of all the cutting out and back on they cause while they are failing.

 

Got the part - it was 56.60, about $61 after tax at local dealer. Installed it, the car starts. Will try riding it a bit later today.

 

put 20 miles with the new part in. So far works well - will see how it behaves on the longer trips.