Cold start issue (only occurs when sat overnight)

[AllHailKingVolvo]

Hi all,
My Torslanda (B200F) has developed an odd starting issue, when it's been sat overnight it will often take prolonged cranking to get it to fire up. Sometimes 20-30 seconds. Once started, it will run perfectly all day and stop/start faultlessly.

I suspect a fuel issue, I haven't changed the fuel filter or underbody pump since I've owned it and I'm curious as to whether it might be suffering from a partial blockage or weak pump which means the car is struggling to make sufficient pressure at the rail for the first start of the day.

Does that sound right, or am I barking up the wrong tree? I've had hot starting issues with the B200F in my 744 which were cured by changing the coolant temperature sensor. Could that be the cause of this issue, despite the problem being the other end of the temperature scale?

I'm keen to diagnose it properly rather than fire the parts cannon at the car as money is a bit tight at the min. Huge thanks in advance for any and all help!

[Clan]

Originally Posted by AllHailKingVolvo

Hi all,
My Torslanda (B200F) has developed an odd starting issue, when it's been sat overnight it will often take prolonged cranking to get it to fire up. Sometimes 20-30 seconds. Once started, it will run perfectly all day and stop/start faultlessly.

I suspect a fuel issue, I haven't changed the fuel filter or underbody pump since I've owned it and I'm curious as to whether it might be suffering from a partial blockage or weak pump which means the car is struggling to make sufficient pressure at the rail for the first start of the day.

Does that sound right, or am I barking up the wrong tree? I've had hot starting issues with the B200F in my 744 which were cured by changing the coolant temperature sensor. Could that be the cause of this issue, despite the problem being the other end of the temperature scale?

I'm keen to diagnose it properly rather than fire the parts cannon at the car as money is a bit tight at the min. Huge thanks in advance for any and all help!

i would connect a fuel pressure gauge and watch it when someone cranks it in the morning , it should go up quickly as soon as you crank , does it prime for a second or two when you put the ignition on?

[AllHailKingVolvo]

Yes I get a couple of seconds of fuel pump buzz when I turn the key. The underbody pump is noisy in general, it runs perfectly right down to the bottom of the reserve so I don't think the in-tank pump is faulty, but I suspect the underbody pump may be weak or the fuel filter partially blocked, causing the cavitation noise.

It's a really good shout to check the pressure at the rail, I have a pressure gauge so will ask my partner to crank it whilst I check the pressure, thanks for the tip!

[Mrbrown]

My car did this and it was moisture getting in under the distributor cap. When I dried the cap inside it would fire right up. Sometimes it’s things like this that you never really think of.

[Bugjam1999]

Try turning the key to make the pump prime about 25 times then try and start it.

My guess is that if the pump is struggling then you’d notice issues at high rpm after it was up and running.

Cheers

[AllHailKingVolvo]

I'm still none the wiser with this. Changed plugs, leads and dizzy cap/rotor arm which seemed to help but it still does it from time to time.

Also, the rev counter is intermittent...could this indicate that the CPS is on the way out, I wonder?