940 having intermittent difficulty starting

[Laird Scooby]

Originally Posted by Laney760

Edited to say that normally, even in winter, I never ever have to give my 940 any gas to start, I don't touch the throttle, just turn the key. Is this unusual? She's been like this since as long as I can remember

That is exactly as it should be Ellie.

Hope your wee beastie fires up soon for you or if it doesn't and gives you an unexpected extra day to the weekend that the sensor turns up so you can get it fitted and be back to normal for tomorrow.

[Laney760]

I got her going after giving her about 10 - 15 minutes for the plugs etc to unflood

When I came out of work I gave her NO gas at all and she fired up fine 2nd attempt, normally when I come out of work this last week it's been a nightmare. So I'm more confident about the starting now, I shan't give her any gas at all tomorrow morning. I think I've been starting off by giving her just a bit as I've not been really sure what's occuring but now I now for sure she's flooding right from the get-go!

I will be interested to see if I see any differences other than normal starting with the new engine coolant temp sensor in, I understand they can affect mpg and idling, etc..

Thanks to all for the advice and help!

[Laird Scooby]

Originally Posted by Laney760

I will be interested to see if I see any differences other than normal starting with the new engine coolant temp sensor in, I understand they can affect mpg and idling, etc..

Thanks to all for the advice and help!

Glad you got started in the end Ellie, the new sensor should make a difference to how it runs in general, improve the fuel economy and idle quality and also starting in general.

You remember driving a car with a manual choke? If you left the choke out, the fuel economy would go down, it would run rough and idle like a bag of spanners.

At the moment, your CTS is telling the ECU the engine is cold so it's running the engine with the choke out for want of a better analogy.

Don't forget to pull fuse #1 before you change the sensor and refit it after - this will clear the fault codes in the ECU so it can relearn the fuel trims from fresh with the new sensor.

[Laney760]

The new sensor is fitted but it hasn't changed a thing, still have the fault but I hadn't seen Dave's post about resetting the codes before fitting it but I've pulled fuse 1 since and put it back and it hasn't made any difference, she still won't start

So much for code readers!?

[Laird Scooby]

That's a pain in the proverbials Ellie!

Couple of questions - when you drive the car normally, you drive off from cold and it changes to LPG once it's warm enough, correct? Then you drive it normally and reach your destination, switch off and go and do whatever you need to do, come back later at some point, start again and whether it's cold or hot, it once again starts on petrol and changes to LPG as soon as it registers it's warm enough.

Assuming this is the normal course of events, can you try switching to petrol manually for the last few minutes of your journey please? I'm really hoping it makes no difference, if it does it would point to a leaky gas injector or similar.

After that i'm wondering if it's possibly a leaky petrol injector causing overfueling. I don't suppose you happen to know if yours has an additional cold start injector?

[Laney760]

After pulling fuse 1, putting it back, getting her restarted then turning her off and reading the codes, the codes have cleared, I get the all clear on ignition and fuel. I suspect more than one thing is wrong. I queried the nearly one year old Volvo fuel pump at the garage but they think they can hear it doing what it's supposed to when I am trying to start and after I stop cranking. I'll see how it goes tomorrow and if no improvement I'm going to replace the crank sensor

[Laney760]

Originally Posted by Laird Scooby

That's a pain in the proverbials Ellie!

Couple of questions - when you drive the car normally, you drive off from cold and it changes to LPG once it's warm enough, correct? Then you drive it normally and reach your destination, switch off and go and do whatever you need to do, come back later at some point, start again and whether it's cold or hot, it once again starts on petrol and changes to LPG as soon as it registers it's warm enough.

Assuming this is the normal course of events, can you try switching to petrol manually for the last few minutes of your journey please? I'm really hoping it makes no difference, if it does it would point to a leaky gas injector or similar.

After that i'm wondering if it's possibly a leaky petrol injector causing overfueling. I don't suppose you happen to know if yours has an additional cold start injector?

I'll try that tomorrow Dave but interestingly I just switched the lpg off altogether and she started 5 times in a row on petrol only 1st time and then got stubborn again. I'll try that with the petrol tomorrow

Thanks so much Dave and everyone, have to go now, big day tomorrow :-)

[Laird Scooby]

I'm glad the fault codes are clear Ellie, i think you may well be right in thinking there was more than one problem causing the same symptom. Interesting it started happily with the LPG off, time will tell and i'm sure you'll work it out.

[Laney760]

Can anyone tell me the Volvo part number for a crank sensor for a 1997 940 B230FK please, I am going to order one, looks a doddle to fit myself

[Laird Scooby]

Originally Posted by Laney760

Can anyone tell me the Volvo part number for a crank sensor for a 1997 940 B230FK please, I am going to order one, looks a doddle to fit myself

As long as you can reach the sensor, the hardest part is not dropping the bolt! If memory serves it's a 10mm head so whether you use a spanner or a socket, tie a length of string round the tool, put a loop in the other end of the string and put the loop over your arm so if you drop it, the loop will tighten and stop the tool from descending somewhere invisible!

Once the bolt is out, move it somewhere safe like your pocket (without a hole in!) and using the "ear" on the sensor, give it a few twists half a turn one way then the other.
If you're lucky, it should pull out fairly easily, if not, use a thin flat-bladed screwdriver to gently lever up each side - you may have to twist it round so you can get good leverage.

Once free of the bellhousing, disconnect the plug (similar to the plug on the CTS) and lift the old one away.

Smear a little Vaseline, silicone grease or red rubber grease on the "O" ring on the new one and on the body (but NOT the tip) of the new sensor and put it in place, gently pressing down with a slight twist if necessary to seat the new sensor and line it up so the bolt hole in the ear is over the threaded hole for the bolt.

Retrieve the bolt from the safe place and carefully fit in the hole finger-tight, give the sensor a final wiggle to make sure it's settled and tighten the bolt with your tool. Finally plug the connectors together and test.

Not sure on the part number and you didn't say if you wanted genuine Volvo (£OUCH!!!) or an aftermarket pattern part - almost always just as good but a lot cheaper!

Your local parts shop/motor factor should be able to get one quickly if they don't have it in stock, they're used on a variety of vehilces besides Volvo. The one in mine is almost the same but the lead is a differnt length and i remember phoning Kia to try and get one - i didn't bother with Ferrari, Bentley and so on. Most parts factors said if i had the 2.3 they had it on the shelf but not for the V6.

I'm guessing this is a hunch/gut-feeling? Normally i'd say test it and make sure but the only real test you could do is next time it won't start, find the cable and give it a shake - that often cures a faulty cable on them which is usually the main problem.

Good luck and let us know how you get on!

This might be helpful if you can't go to parts shops etc :

https://www.ebay.co.uk/itm/Crankshaf...4/372637210085

All similar prices for the same thing on ebay.