Engine won't rev and hunts

[ANDTWENTY]

Originally Posted by Laird Scooby

Probably something along the lines of this then :





First pic is the "virgin" crimped hose fittings, second is what it looks like when it's done. They withstand a lot of pressure, i've used them on hydraulic hoses with 2000+psi in them.

That looks very much like a hydraulic line, it's nothing like that, it literally looks like a rubber/plastic hose just pushed on, kind of worried me that there's no clamp on it but saw in a video that someone else's was identical so must me normal.

[mocambique-amazone]

Don't try to remove the fuel hose from the fitting. You will never get it sealed again.
You will need adapter parts.
The fuel hose of a volvo 700/900 ist special one, a compound made of plastic and rubber.

The kink at the fuel line between pump and filter is a common problem at not very good workshops.

Good luck, Kay

[Laird Scooby]

Originally Posted by ANDTWENTY

That looks very much like a hydraulic line, it's nothing like that, it literally looks like a rubber/plastic hose just pushed on, kind of worried me that there's no clamp on it but saw in a video that someone else's was identical so must me normal.

In that case, don't touch it. There are two main types of flexible fuel line on the Volvo, one is rubber that is secured with clamps, the other is a form of nylon that is a "one time fit only".

The nylon stuff could also be described as "semi-rigid" - if that is the one you're referring to then find a different place to fit the pressure gauge.

[ANDTWENTY]

This hose feels and looks like rubber, not like the one under the car. It's got some decent slack in it, if I can't pull it off I could cut it just after the rail and there's enough slack to push back on after and attach with a clip.

[Clan]

Originally Posted by ANDTWENTY

This hose feels and looks like rubber, not like the one under the car. It's got some decent slack in it, if I can't pull it off I could cut it just after the rail and there's enough slack to push back on after and attach with a clip.

Don't ruin that plastic shrunk on pipe ! (that screw joint is where you fit the volvo gauge ) As i said before if you are going to tamper with a volvo fuel pipe , the one coming out of the fuel pump is the ideal place to fit your gauge as it is already ruined, I would recommend you get the proper volvo plastic pipe for the pump when you have sorted your problem as rubber pipes will fail one day and spray fuel everywhere underneath and you will never notice when driving along until it catches fire .

[Laird Scooby]

Originally Posted by Clan

I would recommend you get the proper volvo plastic pipe for the pump when you have sorted your problem as rubber pipes will fail one day and spray fuel everywhere underneath and you will never notice when driving along until it catches fire .

You mean like the nylon one did on mine? Bosch no longer make that link pipe, despite the fact it is used on countless other cars, Fords, Vauxhalls, Saabs, Mercedes, BMWs, Porsches to name but a few.

It only takes one kinking episode to create a weakness in the nylon pipe - reinforced rubber petrol hose is a better solution long term as it is more flexible and forgiving.
Also any of the new ones Volvo still have in stock will now be "New, Old Stock" so the nylon tube will be several years old to start with. Not a good point to start from!

Periodic inspection of the fuel lines is meant to be a service point and many garages "forget it" as do many owners.

[Clan]

Originally Posted by Laird Scooby

You mean like the nylon one did on mine? Bosch no longer make that link pipe, despite the fact it is used on countless other cars, Fords, Vauxhalls, Saabs, Mercedes, BMWs, Porsches to name but a few.

It only takes one kinking episode to create a weakness in the nylon pipe - reinforced rubber petrol hose is a better solution long term as it is more flexible and forgiving.
Also any of the new ones Volvo still have in stock will now be "New, Old Stock" so the nylon tube will be several years old to start with. Not a good point to start from!

Periodic inspection of the fuel lines is meant to be a service point and many garages "forget it" as do many owners.

what was the fail reason on yours ? These plastic pipes last forever , i should know i've been working on them for nearly 50 years going back to when they first appeared in 1973. Previous to that volvo used mainly metal pipes joined with flexible fabric covered rubber hose . and due to that that's why i say the rubber pipes will fail at some point , I have seen people's bodges fail on a few occasions out there in the real world . certainly before a nylon one fails . The nylon one will fail where it has been tampered with or damaged by something not time ..

[ANDTWENTY]

So I grabbed another gallon of fuel and a 2L bottle of meths, chucked in half the petrol then mixed the meths with the remaining fuel and put this in. Left it for a while while I changed the MAF and took the fuse out, left it for maybe 10 mins then started the car. Let the car idle for a while and revving it occasionally, the problem still persists. Would the meths have had time to react or should I leave it longer?

Going to try disconnecting that hose on the back of the pump and test the pressure.

[Clan]

Originally Posted by ANDTWENTY

So I grabbed another gallon of fuel and a 2L bottle of meths, chucked in half the petrol then mixed the meths with the remaining fuel and put this in. Left it for a while while I changed the MAF and took the fuse out, left it for maybe 10 mins then started the car. Let the car idle for a while and revving it occasionally, the problem still persists. Would the meths have had time to react or should I leave it longer?

Going to try disconnecting that hose on the back of the pump and test the pressure.

i always remember in the official green volvo manuals for the 240 that they recommend a pint of turpentine in the tank to emulsify any water droplets which then get injected into the engine and burned , meths evaporates very quickly . ( and might give you a power boost for a while :-) )

[Laird Scooby]

Originally Posted by Clan

what was the fail reason on yours ? These plastic pipes last forever , i should know i've been working on them for nearly 50 years going back to when they first appeared in 1973. Previous to that volvo used mainly metal pipes joined with flexible fabric covered rubber hose . and due to that that's why i say the rubber pipes will fail at some point , I have seen people's bodges fail on a few occasions out there in the real world . certainly before a nylon one fails . The nylon one will fail where it has been tampered with or damaged by something not time ..

Manufacturing defect causing a pinhole in the wall of the nylon tube. The nylon can and does fail after time, after all it's a petro-chemical polymer so will decay over time as well.
I've known many nylon pipes to split/burst even when just used for compressed air which thankfully didn't spray any "nasty" liquids around.
The majority of those were in a more aggressive environment to be fair and nylon is a long-lasting plastic.

Looking at the OPs post it's easy to see how his failed, some spanner monkey tightened the fuel banjo without a backing spanner to prevent counter-rotation, almost certainly at the other end of the filter.

Something that has crossed my mind and i'm sure it can't be done as the banjos are different sizes but the filter could possibly have been fitted back to front. I know Saab use the same filter (and pump, link pipe etc) but they use Dowty seals instead of copper or aluminium washers on the banjos and if memory serves, one is M12 and the other M14 on the Dowty seals, could be wrong though.
However, if they are different sizes then in theory it should be impossible to get the filter back to front.

Turps being oily tends to float on water, rather than emulsify with it as meths does,

The engine needs to be running for the meths to do its work and does take a bit of time. When i get condensation in my tank(s), i usually drive to Toolstation and get a 2L bottle of meths, do my food shopping and then add the meths to the tank before adding petrol.
Usually it's still fluffing at idle/pick-up most of the way home (12 ish miles) and the next time i use the car then improves fairly quickly after that. It won't evaporate in a tankful of more voltaile fluid such as petrol unless the petrol is able to evaporate quickly as well.