Hi friends, I have a S40 2.4i 2010 with a very weird problem, the engine crank and start without problem having ambient temperature (cold condition), when the engine is hot (for example inmediatly after stop the engine), the engine start with any problem as well, but whether I wait 10 minutes after to stop it, the car do crank for 10 seconds and then start. I've checked using ODB the fuel pressure, having this results

Working Pressure: 55 PSI (no problem)

Pressure inmediatly after to stop de engine: 42 PSI (I think the pressure decreases a lot), but with this fuel pressure the engine crank and start OK

Pressure 10 minutes after to stop de engine: 30 PSI, in this case I have the starting problem.

I think that the problem is located in the fuel regulator and I think that component is located inside the fuel pump.

There is another possibility that the problem could be the PCM, but this could be the cause if the pressure decreasing was normal (I don't think so) if the PCM could control the pressure level (after to stop the engine).

What do you think, are normal the pressure values?

Can be the problem the fuel regulator or PCM?

I've changed the fuel pressure sensor, having identical pressure values.

Thanks for your help!!

 

I think you're spot-on. AFAIK, the regulator is part of the pump (and even if it isn't, there's a good chance that the pump is the problem anyway). Having already changed that FP sensor (smart!), you've already picked all the low-hanging fruit. ;-)

 

Our 2008 S40 2.4i has this same problem and the car is with our independent Volvo mechanic for fuel pump replacement. I monitored fuel rail pressure using an analog gauge on the Schrader port and cross checked with a plug-in Bluetooth analyzer. Fuel pressure drops quickly when engine shuts off and it appears that fuel gradually drains back to the tank over time. Car has no problem starting even with 4-5 psi but being a liquid, pressure will drop quickly even with small volume draining back. The headache is that the tank must be dropped (no access plate) to get the fuel pump out and the pump appears to have an integral check valve or similar mechanism (i.e. not a separate regulator). Mechanic is waiting for the pump to arrive but will update once the pump is replaced. As a comparison, I monitored fuel pressure on our 2011 S40 T5 and it was holding 40 psi after sitting overnight. That clearly points to problem with fuel pump. The 2008 idles and accelerates smooth as silk and always starts but the long crank is irritating. Car has 100K miles on it.

 

Fuel pump on our 2008 S40 2.4i was replaced by independent Volvo mechanic. The job is major since the fuel tank must be lowered to access the pump and removal of the plastic retaining ring is difficult without the special service tool. Long crank time issue was solved. Inspection of the old pump (which looked brand new) showed a crack in (what I am guessing) is the fuel check valve (see photo). Luckily, forward fuel flow was sufficient in spite of the crack but fuel pressure could not be sustained when engine/pump was shut off - leading to long crank time.

crack in fuel pump check valve - just to the left of the rid/spring on the right. cause of long crank time.

 

Thanks friends for the tips, I started last weekend the task at home, but when I lowered the fuel tank I noticed that I bought the wrong fuel pump, I had checked codes/part numbers using VIDA and a lot of websites, all those sources show pump with just one out fuel line, but when there is an external fuel filter, the fuel pump must have two lines:

main line out go to the fuel filter and then to the engine
second line returning after the fuel filter, there is a T connection in the fuel line returning to the pump.

This type of fuel pump is not common so I had to order a new one to Germany, the previous was bought it in Rockauto.


Another tip, try to disconect the fuel lines previous to see them, when I lowered the fuel tank, suddenly I broke it the main line (left circle), right circle shows the returning line.

Fuel filter is located close to the rear right wheel (easy access)


The part number for a pump with 2 lines is 0 580 314 051 or 0 580 314 050.