V70 petrol: Fuel starvation only when hot.Advice needed

[CSCUK]

Thanks. All noted and to be duly applied.

Originally Posted by duke1

the little water temperature sender housed alongside the thermostat :

Where exactly is the thermostat located on my model's engine?

[Luxobarge]

Originally Posted by CSCUK

Thanks. All noted and to be duly applied.



Where exactly is the thermostat located on my model's engine?

Inside the aluminium housing on the engine at the end or the radiator top hose - driver's side of the engine. However, if the temperature guage is reading correctly I'd do all those other things first before fiddling around with the temperature sender. Personally I don't think your symptoms correlate to a faulty temp sender.

[CSCUK]

Yea, temperature gauge is reading completely normally. The needle sits in the same place as always once engine warm.

I'll check the distributor components and plugs first.

As far as cleaning plugs/distributor contacts etc.
Does anyone advise any particular cleaning method other than wire brushing?

[ITSv40]

Originally Posted by CSCUK

Yea, temperature gauge is reading completely normally. The needle sits in the same place as always once engine warm.

I'll check the distributor components and plugs first.

As far as cleaning plugs/distributor contacts etc.
Does anyone advise any particular cleaning method other than wire brushing?

If the plugs are fouled and need cleaning, they need replacing. The distributor cap contacts can be cleaned with some fine wet and dry, likewise with the points, fold a bit of wet and dry in half and pull back and forth between the points. If either the cap contacts or points show any sign of pitting once cleaned they need replacing ingredients. You may find the points will be pitted on one contact and a little pimple formed on the other.

[4x4]

Originally Posted by ITSv40

If the plugs are fouled and need cleaning, they need replacing.

Agree, genuine Volvo plugs for the 2.5N/A are not expensive.

Originally Posted by ITSv40

The distributor cap contacts can be cleaned with some fine wet and dry.

Never use wet & dry or any other sandpaper type product on the distributor cap or rotor arm. If there is build up on the contact posts a blunt screwdriver blade to carefully remove the hard build up is the preferred method, to clean the rotor arm rub on the sidewall of your tyre. No points in the 850.

Aftermarket distributor caps are poor quality, replace with genuine Volvo or Bosch

[Luxobarge]

Originally Posted by ITSv40

The distributor cap contacts can be cleaned with some fine wet and dry, likewise with the points, fold a bit of wet and dry in half and pull back and forth between the points. If either the cap contacts or points show any sign of pitting once cleaned they need replacing ingredients. You may find the points will be pitted on one contact and a little pimple formed on the other.

No points on these mate, electronic ignition - I'm sure a man of your calibre knew that .
Distributor "contacts" aren't actually contacts, they're made of aluminium and usually get a build up of aluminium oxide which is a hard white powdery deposit, which can usually be chipped and scraped off with a screwdriver or other suitable blade. It has to be said though, if there's a lot of muck in there it's probably better to replace it, but only with a decent quality one as 4x4 says. I generally wipe the inside of the plastic casing with a rag dampened with a bit of WD40.

[ITSv40]

Yes, the last distributor I dealt with was on the Silver Cloud - many years ago..

[CSCUK]

Electronic ignition on my model for certain.
I'll use screwdriver for any cleaning attempt
cheers for straightening that out.

[richmac]

Hi,

Everyone check my tech, please, but I would start with what looks like a bodged crank position sensor connector wrapped in tinfoil in your photo, (and perhaps check the other tinfoil wrapped item below the dist).

Otherwise, your dist cap and leads aren't original so should be ok age wise. The fact that it starts so well cold after long lay offs implies the ignition system is fine.

I would go for the temperature sensor next as previously suggested as this is a temperature related issue; it's a multi signal item, ie: not just the gauge but also the ECU so it can hide a fault.

Best regards,

Rich.

[CSCUK]

The tinfoil insulated cables are for the camshaft sensor and crank position sensor.

Both found to be functioning okay 18 months ago, after they were WRONGLY suspected of causing the fault of motor-failing-to-fire (through cable insulation breakdown and interference corrupting single)
The cam sensor itself was renewed.

However, the fault was actually the fuel relay, and after renewing it, the motor started and ran perfectly.

The tin foil was left on the cables from when I had insulated them to attempt to stop interference, after wrongly suspecting the fault could have been insulation breakdown, when the fault was really just the fuel relay.