Hot start / warm start / restart issues again!

[Laney760]

Originally Posted by Laird Scooby

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.

I had a brand new CPS as well as temp sensor in Aug/Sept 2019. Isn't there another temp sensor in the engine or won't that affect starting? Is there another inline fuel pump as well or not in the 97 940?

[griston64]

Originally Posted by Laney760

I had a brand new CPS as well as temp sensor in Aug/Sept 2019. Isn't there another temp sensor in the engine or won't that affect starting? Is there another inline fuel pump as well or not in the 97 940?

97 940 only has one fuel pump in the tank

[Laird Scooby]

Originally Posted by Laney760

I had a brand new CPS as well as temp sensor in Aug/Sept 2019. Isn't there another temp sensor in the engine or won't that affect starting? Is there another inline fuel pump as well or not in the 97 940?

There is another CTS in the engine, towards the front of it but that is only for the temperature guage, doesn't effect the running (or starting) at all.

On the 96-on cars, there was only an in-tank high pressure pump instead of an in-tank high-flow, low pressure pump and an underbody high-pressure pump.

I've just had a really horrible thought. What if the pump that came from Sweden was the low-pressure, high-flow in-tank variety instead of the high-pressure high-flow type? That might explain a lot!

***EDIT*** With that in mind it might pay to have a fuel pressure test done, should be 43.5psi but they need to bypass the relay to check it. They should have details of that if they have something like a computerised workshop manual and tuning data.

[Volvo_Utrecht]

There is a (tyre) type pressure valve on the fuel rail that uou can use to check the pressure

[Laney760]

Cheers guys. More things for me to get checked out by my mechanic or check out myself. I can find the Volvo receipt for the fuel pump and check the part number to make sure they sent the right one.

[bob12]

This sounds so much like the difficulties I have with my '90 745 (LH2.4)which I have commented on over many years.

I have replaced everything and once even had the ecu checked. All to no avail. The fuel pressure valve at the end of the rail is also a prime suspect.

I understand that the first ecu's ( xxxx 590) that came with LH2.4 had a 'problem' and were quickly changed/upgraded by Bosch after about 9 months.

I have learnt to live with it. When the car doesn't start immediately I just floor the accelerator pedal and keep cranking until it fires up. Flooring the accelerator stops the injectors working and flooding the cylinders. It did mean that I put a more meatier battery in!

I have a spare ecu that worked well once in the day and if I get a chance this Summer I might swap it over and see what happens but having got used to the starting difficultiy I don't treat it as a problem now .... that is of course until I have to replace the starter!

Bob

[Rversteeg]

Does the engine start on LPG or petrol? Some systems always start on petrol and automatically switch over to LPG after a short while. If it starts on both fuels at the same time the mixture will be far too rich and only a full throttle start could bring it to life.
Rob

[Laney760]

Originally Posted by bob12

This sounds so much like the difficulties I have with my '90 745 (LH2.4)which I have commented on over many years.

I have replaced everything and once even had the ecu checked. All to no avail. The fuel pressure valve at the end of the rail is also a prime suspect.

I understand that the first ecu's ( xxxx 590) that came with LH2.4 had a 'problem' and were quickly changed/upgraded by Bosch after about 9 months.

I have learnt to live with it. When the car doesn't start immediately I just floor the accelerator pedal and keep cranking until it fires up. Flooring the accelerator stops the injectors working and flooding the cylinders. It did mean that I put a more meatier battery in!

I have a spare ecu that worked well once in the day and if I get a chance this Summer I might swap it over and see what happens but having got used to the starting difficultiy I don't treat it as a problem now .... that is of course until I have to replace the starter!

Bob

Hi Bob. Mine is a 1997 late 940. It doesn't sound quite the same as my problem. I have to pump the throttle before I start and then start on almost full throttle and then I have to 'catch' it. If I don't get it right she will not start under any circumstance for about 5 minutes. I can try and restart after first fail with foot on the floor for ever or no gas for ever but she simply will not start unless I catch it first time around using full gas to start. She has to have this 5 minute wait (if I don't get her started first time around), which I used to think was flooding but then it can't be if she will only start with full throttle?

[Laney760]

Originally Posted by Rversteeg

Does the engine start on LPG or petrol? Some systems always start on petrol and automatically switch over to LPG after a short while. If it starts on both fuels at the same time the mixture will be far too rich and only a full throttle start could bring it to life.
Rob

Hi

Mine is the PRINs, starts on petrol, goes over to gas. She always starts on petrol and then switches over to lpg. I can choose to run on petrol alone but she still has the same starting problem even if I run on petrol, even if I have no lpg in the tank at all.

[Laney760]

There is no way this could be linked to throttle cable is there?