intermittent start problem driving me mad

[halfnelson]

Hi All,

My otherwise reliable Torslanda has developed a habit that's driving me crazy. Occasionally when starting it will fail to catch straight away, then refuse to start. Or I'll start the car, move it to get access to the boot. Then it won't restart. Otherwise it's been great, no problems. The thing is, it always happens at the worst time - freezing cold, getting ready for a journey etc. Never when I have time to search down the issue. Then, the next day, starts first time.

My guess is something to do with cold start / fuel pump / sensors?????

Anyone have experience with something similar?

Thanks

Chris

[AlexO]

Halfnelson,

As always the best place to start is your diagnostic box on the inside passenger wing in the engine bay. Go here for the fault codes: https://www.volvoforums.org.uk/showthread.php?t=122391

I've had a similar problem in the past that I've resolved first by replacing the HT leads and distributor cap/arm and most recently by cleaning the MAF with carb cleaner. It's amazing the difference it's made to my overall engine sounds and happiness

Hope thats helpful,

Alex

[Clifford Pope]

Is the orange lambda light on? If not, there's no point in checking for codes.

I had exactly that fault with a Torslanda once, and after replacing everything else I tried the Crank Position Sensor - instant cure.
Apart from that, there's the usual fault - fuses 4 and 6 corroded, and then the fuel pump relay. (Test the relay by connecting a short wire between fuses 4 and 6 to bypass the relay so the pumps run continuously.)

Experience since has been that occasional failure to start is usually the CPS or the fuses, whereas cutting out without warning is the Ignition Amplifier Module on the wing just in front of the battery.

That's always assuming new plugs, HT leads, distributor cap and rotor arm.

[halfnelson]

Thanks for the suggestions. Started with the obvious and easiest just to eliminate them - rotor, cap, leads and plugs. All were new only a couple of months ago for the winter so thought they'd probably be fine. Looking at the arm, fine, but the contacts on the cap looked quite worn. Swapped it over and started first time.

Now my question is - why would a cap only last a couple a months? Could the coil be at fault?

Thanks, Chris

[TheLeeds]

When you turn the key to the ignition position, can you hear the fuel pump priming the injectors ? If not, maybe check the fuel pump relay. Not sure what it's like on 240s.
My 97 model 940 used to do that, but it's been fine since I resoldered the dry joints in the fuel pump relay.

[dan 244]

Possibly the same as my dad had with his 1989 240, would run fine for days, then randomly turn over but nothing happens. We changed the fuel pump relay, which we was sure was what it was. But for some reason there wasn’t a feed to the fuel pump under the car, which I think should be there when the key is turned to the turning over position and when running. So as a temporary fix we put the positive to the pump on an auxiliary feed in the fuse box, really easy as spade connections. It means that if you have the ignition on and the car not running the pump runs through so not ideal, but meant the car started and ran ok. Incidentally you could try cleaning and wiggling all the wires in the fuse enclosure as it is a bit prone to moisture in the door pillar as water drains from the vents under the windscreen down the back there.

[Clifford Pope]

Originally Posted by TheLeeds

When you turn the key to the ignition position, can you hear the fuel pump priming the injectors ? If not, maybe check the fuel pump relay. Not sure what it's like on 240s.
.

I think perhaps that basically depends on how good the fuel pump valve is at retaining pressure when the car isn't running. I've had some that make the little priming noise, and my present car which doesn't.
Hence the procedure in the book for releasing the pressure carefully when disconnecting the pump or pipework.

But I think I've also read that the pump can't run for more than an instant until it gets the signal from the crank sensor that the engine is turning over.

[halfnelson]

Originally Posted by Clifford Pope

I think perhaps that basically depends on how good the fuel pump valve is at retaining pressure when the car isn't running. I've had some that make the little priming noise, and my present car which doesn't.
Hence the procedure in the book for releasing the pressure carefully when disconnecting the pump or pipework.

But I think I've also read that the pump can't run for more than an instant until it gets the signal from the crank sensor that the engine is turning over.

At the last service I had the pumps checked and filters changed so I think they're not the problem. Weirdly I think it's an ignition issue because as soon as I swapped the cap it fired up first time. My theory was that when turning over with a rich start mixture, the sparks were too weak to fire.

What I can't work out is why the cap is only lasting a few months?

[classicswede]

Running on petrol they are not normally so fussy on condition of the cap.

Some cheap caps can struggle from day 1, what cap is it you have been using?

[halfnelson]

Just standard service item... Came in the blue Volvo box.