Hot start / warm start / restart issues again!
 

Hi Guys

Having had a starting issue not that long ago, about 18 months ago, and put a lot of new parts on the car, since the weather started getting a bit warmer a couple of weeks ago I have a hot starting problem again.

Cold starts I have to push the throttle to the floor and then hold it about 3/4 ways down and then 'catch' her when she fires, this worked well all winter for every start until the weather started warming up. Now restarting after stopping can be a problem. When she won't hot start I just have to sit and wait about 10 mins and then I can normally get her to fire but this is not a great situation to be in sometimes!

The only part I am aware that I haven't renewed is the lamba probe, she last had one of those in c 2015, about 50,000 ago. The throttle body is regularly cleaned and she she is regularly serviced. Its not that long ago since I chucked a bottle of meths in the tank.

Would somebody be kind enough to supply or link to a work through part by part, step by step to eliminate hot starting issues please?

Many thanks

First thing i'd try is switching it to petrol about 5 minutes before you plan to switch the engine off Ellie. The reasoning behind this is that there may be a leaky LPG injector so this would give it time to (hopefully) burn off that excess LPG that's leaking past once the LPG system has switched off. If that improves things, then you know you need to concentrate on the LPG injectors perhaps needing renewal, cleaning or similar.

If it makes no difference, it's likely it's a petrol injector leaking. However, don't discount the possibility of the CTS (Coolant Temperature Sensor) causing rich running overall and excessively rich mixture on start up but that said, there could also be an air leak between the MAF and throttle body although that will normally give other problems like flat spots etc.

Out of interest, how long have the LPG injectors been on the car?

Cheers Dave.

No improvement when running on petrol alone and not using the lpg system at all.

I've already had a new coolant temperature sensor.

I'll get my mechanic to check out the petrol injectors and the possibility of an air leak between the MAF and throttle body

Hi Everybody

I haven't had the time to speak to my mechanic or put the car in the garage but I do have an update on this.

I have discovered that I need to give the car a lot of gas for hot starts as well as cold starts now. For the first 7 years or more of ownership I never had to give her any gas to start, all I did was turn the key. Then I had to start giving her a lot of gas for cold starts and ''catching'' it with the pedal near to the floor. Then I started having trouble with hot starts and am finding that I can get her started most times on hot starts with the same procedure as cold starts - pump the throttle to the floor to start and then hold it near to the floor and 'catch' it as she starts and she starts with a very high vroom at high revs. Air filters and fuel filters are good, throttle body is regularly cleaned, car is regularly serviced. Any ideas please? Fuel pump relay maybe?

Those symptoms to me would make me suspect the ECU temp sensor, you say you have had a new one, when was this and what brand? I would be checking the resistance figures to check that it is actually working. You probably know but just in case it is the rear most temp sensor under the inlet manifold not the one at the front.

If you have a multimeter run the car up to temp then unplug it and check the resistance from each pin to the block/head.

Hi

I bought a Bosch one from an Ebay seller in August 2019

''0280130069 BOSCH TEMPERATURE SENSOR [SENSORS] BRAND NEW GENUINE PART''

I'm beginning to think, after looking at this old thread, that this problem is a re-run of the old one in August 2019 whereby I replaced almost everything and the temperature sensor replacement made no difference but gradually, bit by bit, after replacing everything under the sun the problem was a lot better but she still didn't start like she used to, just on the turn of the key with no gas?

https://www.volvoforums.org.uk/showt...or#post2547734

I'm wondering if your fuel pump is playing up Ellie or perhaps fuel pump relay or CPS.

Silly question, have you checked all the fuses and relays are pushed down fully into their respective homes? Had a weird one on mine some time back where the main fuel pump fuse worked its way out and stopped both pumps running on mine. :err:

Also it's an LH2.4 system on yours so will always turn over a couple of times before firing, rather than starting first turn of the engine.

Do you remember my fuel pump failed and I had to wait two weeks for a brand new one from Sweden back in late 2018 I believe, surely it can't be failing again? Although to be fair all the starting problems came after that was fitted! I have another fuel pump relay, I will fit that. CPS, whats that an acronym for, sorry? Crank position sensor?

I had vague memories of you having the fuel pump changed. Wouldn't have thought it would be failing again so soon but it's a possibility.

Might be better trying the fuel pump relay first though.

CPS is indeed Crank Position Sensor, if that's playing up it won't generate sparks at the coil for the plugs or start the fuel pump (you only have one in the tank i think) running. Got vague memories of you changing that some time before the pump though.