My 2004 V70 AWD is becoming hard to start. After sitting for several hours, it takes several seconds of cranking, to get it to start. Once it starts, it runs fine & can travel at 75mph for hours with no problems. Is this a check-valve issue, fuel pump pending failure, or something else? Thanks for any help.

I ordered wrong fuel pump initially. Anyone interested in new V70 fuel pump see classified section.

It appears that the pressure drain back is in at least part to a leak in the fuel pump assembly top where the fuel line attaches at 6 o’clock. When I removed the cover, I could see fuel in the depressions in the round plastic casting where the fuel comes from the tank. Replacing the pump assembly should take care of this. Thanks for all the help.

Replaced fuel pump using this info:
https://www.matthewsvolvosite.com/forums/viewtopic.php?f=9&t=67480
Process went smoothly.

How many miles on your car?

Cross the "T"'s and dot the "I"'s first.
1) Battery fully up-to-snuff? Clean engine ground?
2) Spray clean the MAF and allow to air dry
3) Plugs CORRECT and OK?
4) Fuel filter at or well above 100,000 miles?
5) Air filter packed with crud or passing air as it should?
6) Check for disconnected vacuum lines and/or split air handling hoses.

Do a code search
A failing CKS (Crankshaft positioning sensor) can create a hard start condition.

Check fuel pressure at the rail. A failing regulator can effect starting.


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Our 3rd V70

Battery new in Feb. 2019
MAF Cleaned
Volvo plugs <1yr old
Changed fuel filter yesterday
New air filter yesterday
Vac lines appear all connected.
Fuel pressure 56psi bleeding down to 6psi over 3 hours.
After sitting overnight, turning key on to PII did not pressurize fuel line & took several seconds of cranking, short wait (key off), then started right away. Pressure went up to 56 psi & stable even while increasing rpm's.

Kudos for hooking up a fuel pressure gauge! The pressure should go to zero after X hours, but the fuel line should not drain back to the tank, which is what I suspect. The constant pressure you have will not change with rpm's while not in gear, no load on the engine.

It might be your fuel pump, probably original, and not fun to replace. Part of the pump is a valve that closes to keep fuel in the line, plus, if the pump is getting weak...

There is also a fuel pressure sensor up on the fuel rail which is a known problem.

Too bad you can't drive and see the fuel pressure under load.
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Keeping it running is better than buying new

Will adding a marine anti-drainback valve to the fuel line solve this? If the fuel pump is faulty, what will the fuel pressure do when driving?

The anti drain back valve has been added to some cars, but I don't think it is a good idea. If the fuel pressure doesn't fluctuate, the pump may have a sock coated with garbage or is about to fail. The speed of the pump is regulated by the PEM which gets its signal from the fuel pressure sensor on the fuel rail. Convoluted process to say the least.

Unlike the 850 cars, the pump no longer primes the pressure with the key turned to posII.
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Keeping it running is better than buying new

I taped the mechanical gauge to my windshield & went for a drive. Accelerating up long & short hills. Needle was hard to read but appeared steady at 56 psi (maybe +/- 0.5 psi).

I suspect your gauge is reading a little on the high side as 44psi at idle should be normal. I would suspect that the fuel pressure is OK. A really good code reader can check fuel pressure from the engine monitors.

Try this with your pressure sensor still plugged in and the engine ice cold (in the morning). The fuel pressure should be zero. Try your normal start attempt, then see what the pressure is. If it is 20-30psi, the fuel has drained back to the tank and the line was empty. If the reading is 55psi, then the fault could be in the PEM.
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Keeping it running is better than buying new

Turning the key on & off 3-4 times brings the pressure up high enough to start right away. Is changing the entire fuel pump the best or only way to keep fuel from draining completely back to the tank?

Here's a good option, that beats swapping out the fuel pump.

https://www.matthewsvolvosite.com/forums/viewtopic.php?t=38593

Good luck, Bill

BTW, car has 234K on it.

Just curious..... What happens if.....

On the first start of morning you turn the key to Pos II to let the pump prime but DON’T crank the starter. Instead, turn the key off and repeat the process a few times, monitoring the pressure gauge all the while. I suspect you will see a psi increase each time you prime the pump. Once it reaches 50-56-ish psi THEN crank the starter. How quickly will the engine fire up?

Sounds like whatever is supposed to prevent fuel drain-back ain't doing its job. I've never had to repair either one of our P2 fuel systems other than pressure sensor replacements on both cars. So I will have to defer to someone who has knowledge of the pump/check valve end of the system.

Good luck!
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (STILL not road worthy!)

4 off-on cycles boosted the pressure to 50psi. Then it started right up.

After sitting overnight, turning on the key to PII raised the pressure to 18psi. Cranking for a few seconds, but not starting, boosted the pressure to 48, but after that it fell rather rapidly down to 30psi in a few minutes. I turned the key on again to PII & the pressure went up to 48, but again started to fall.