Occasional loss of power.

[Delta66]

A good few months back, maybe about 6 months, I put in an additive "Wynns Dry Fuel" to deal with lumpy running, probable/possible water in the tank.

As soon as I put the additive in, I would experience a loss of power for a few seconds, which I presumed was the additive/water mix going through and not burning like the petrol does.

At first I got that loss of power quite regularly (every second day during a commuting week). Then it tailed off, but occasionally it still happens, such as today.

Is it possible the additive water mix is still in the system after so long and at least a dozen tank fulls of petrol?

[Dirty Rooster]

Originally Posted by Delta66

Is it possible the additive water mix is still in the system after so long and at least a dozen tank fulls of petrol?

I think not.

Did you change the fuel filter? Not suggesting you do, just asking if you did.

[Laird Scooby]

Originally Posted by Delta66

A good few months back, maybe about 6 months, I put in an additive "Wynns Dry Fuel" to deal with lumpy running, probable/possible water in the tank.

As soon as I put the additive in, I would experience a loss of power for a few seconds, which I presumed was the additive/water mix going through and not burning like the petrol does.

At first I got that loss of power quite regularly (every second day during a commuting week). Then it tailed off, but occasionally it still happens, such as today.

Is it possible the additive water mix is still in the system after so long and at least a dozen tank fulls of petrol?

Not a hope it will still be in your fuel system now! How much fuel was in your tank when you added it?

After looking into the MSDS and other references for that and similar products, i can confirm the main ingredient is methylated spirits and for the amount you get in the tub/bottle it's vastly overpriced.

Much better off buying this :

https://www.toolstation.com/shop/Pai...+Spirit/p99550

Buy the 2L version, it will treat up to 4 gallons/18L of fuel - anymore than that and it won't be effective.

Chances are you've still got condensation in your tank and will have until you get the level down to about 1/4 tank or less then add the 2L bottle of meths, drive it until almost empty and then top up with fresh fuel.

Try to use branded fuel, BP, Shell or similar, most supermarkets (except Sainsburys) use a variety of suppliers and the quality is variable.

This should eliminate fuel as being the source of your problem.

Then if the fault continues or gets worse, it could be time to investigate other things like the RSR, CPS and so on that can also cause loss of power.

Also when do these power losses occur? Is it always after turning or on the over-run or when driving gently or what?

[Delta66]

Originally Posted by Dirty Rooster

I think not.

Did you change the fuel filter? Not suggesting you do, just asking if you did.

No, I was thinking that may be the next job to get done. For about 20 years the car was owned by someone who worked abroad. It did a few thousand miles a year, most of which was over a few months and then it was garaged.

Could there be crap in the filter that sometimes gets through to the engine and that causes the problem?

[Delta66]

Originally Posted by Laird Scooby

Not a hope it will still be in your fuel system now! How much fuel was in your tank when you added it?

About a quarter of a tank.

.....


Then if the fault continues or gets worse, it could be time to investigate other things like the RSR, CPS and so on that can also cause loss of power.

Also when do these power losses occur? Is it always after turning or on the over-run or when driving gently or what?

It happens during normal running, so if I am on the move there is a loss of power, or if stopped at lights or in traffic, it stalls. On the move the loss lasts for 10 seconds or so and then the power comes back. If stalled it takes a few turns of the engine to get going again.

That is why I think it is fuel related.

[TonyS9]

Its also possible your fuel pump is failing, thats how mine went. Faily intermittent total power loss then no start.

Check how it sounds on priming, should be a nice high pitch whine and not grindy.

[Laird Scooby]

Originally Posted by Delta66

About a quarter of a tank.



It happens during normal running, so if I am on the move there is a loss of power, or if stopped at lights or in traffic, it stalls. On the move the loss lasts for 10 seconds or so and then the power comes back. If stalled it takes a few turns of the engine to get going again.

That is why I think it is fuel related.

I'd try the meths treatment as described in my post - that way it eliminates fuel as being the problem.

There could be other problems such as a weak fuel pump, overheated fuel pump fuse in the fusebox, failing pump or relay, faulty CPS (does the rev counter completely die when the loss of power occurs?) or something else, even a broken HT lead somewhere.

You need to start somewhere, as you think it's fuel related, do the meths thing first and we can go from there.

[Delta66]

Originally Posted by TonyS9

Its also possible your fuel pump is failing, thats how mine went. Faily intermittent total power loss then no start.

Check how it sounds on priming, should be a nice high pitch whine and not grindy.

No grinding noise, but if it does fail and refuse to start, I will remember that as a possible. Thanks.

EDIT - did some checking

https://www.volvoclub.org.uk/faq/Fue...blemsDiagnoses

"Symptoms that may indicate low fuel pressure include hard starting, rough idle, hesitation, stumbling, loss of high-speed power, lean misfire (which may set an OBD trouble Bosch Under-Car Fuel Pumpcode) or pinging/knock due to low fuel pressure."

The only symptom is loss of power under normal driving. I borrowed a code reader a few months back and there was no code related to the fuel pump. That would suggest it is OK.

[Delta66]

Originally Posted by Laird Scooby

I'd try the meths treatment as described in my post - that way it eliminates fuel as being the problem.

There could be other problems such as a weak fuel pump, overheated fuel pump fuse in the fusebox, failing pump or relay, faulty CPS (does the rev counter completely die when the loss of power occurs?) or something else, even a broken HT lead somewhere.

You need to start somewhere, as you think it's fuel related, do the meths thing first and we can go from there.

Since Dry Fuel is basically meths, the problem started after I added the Dry Fuel and the consensus is that there will be no more of that additive left, I think I can rule out it as the cause and would be reluctant to add more.

The revs do drop as the power drops, the car will not rev and even foot to the floor with the accelerator produces nothing, the car keeps slowing. I am now careful about foot to the floor, as the power returns all of a sudden and the car will shoot off.

I replaced the HT leads a while back when trying to sort uneven idling.

[Stephen Edwin]

Delta. I can't advise. I am wondering in case it helps any advisers. Is it a loss of power as in total loss of power, or a significant reduction of power, a refusal to accelerate, a slowing down of the vehicle perhaps?

Reading between the lines I'm guessing a reduction of power.

Dave. You mentioned the possibility of an over heated fuel pump fuse. Do the 700/900 cars have fuse boards designed for ceramic bodied fuses as per the 240?