940 Estate In Tank Pump Replacement

[Steve 940]

Had booked a couple of days off in case the car didn't pass MOT yesterday (ever the pessimist &#128512 I now have two day, so as weather is fine to be grovelling around, I'm doing my in tank pump replacement as I still have a lot of main pump noise, and I just keep putting it off.

Have got all clamps loose, helped no doubt by application of penetrating oil that I have put on probably 3 times in the last few months, when I bottled out of proceeding further!!

Main feed outlet looks a bit different as FAQ indicate a quick release type?? but anyway, before I pull everything out, is it worth putting a spare piece of tubing onto the main outlet routed into a tub under the axle, and connect up the loom to test turning the key for a second???

I know it won't prove its delivering the right volume, but as it stands I'm still not certain if it works or not as I haven't been able to hear any pump noise using tube into filler neck.

Appreciate any thoughts before diving in further, as I am just worried I will knock something when trying to get the whole unit back in and sealed up.

Cheers
Steve

[Forrest]

What you've got there looks very similar to the one on my 1994 940. See picture in post 8 on this thread.

https://www.volvoforums.org.uk/showthread.php?t=312783

I don't see that testing the pump as you suggest would do too much harm since if it does run it will be operating in fuel as it is designed to do. However, if I were going to do that I would disconnect the main pump before proceeding because otherwise you run the risk of running that one dry.

It really isn't as bad as some of the posts make out getting the fuel sender out and from the symptoms you've been describing I suspect you will have to sooner or later. The worst part I found was that some of the hoses get in the way. I have a recollection that the large hose has a branch that connect to the fuel tank. You probably don't want to put that under too much strain.

Good luck.

[Steve 940]

Hi Forrest,

Many thanks, and I am indeed armed with your previous posts and links all printed off and spread around the boot.

Yes I was just looking at the large filler house and was about to undo the rear jubilee type clip, when I saw it has a smaller hose branching off and screw head to undo it is totally inaccessible, think I'll leave that alone and see if I can wriggle the unit out.

Have main large clamp slightly loose, bottom hose has the type of clip where you compress the little tags together to expand, but looks a bit of a so and so to access.

Cup of coffee I think before diving in past point of no return😀

Cheers
Steve

[Steve 940]

Hi,

Got now got everything loose apart from fuel return hose clip as I can't access it to release at the moment.

Just can't see how it's going to be possible to extract the whole unit as the short section of main filler hose looks as though it will get in the way, ideally would be good to remove, but the small branch off this main filler hose has the torx head jubilee clip facing upwards so inaccessible to get to the head??

Does the short section need to come off?? I think in the FAQ photo section it has been removed, but perhaps more for ease of showing the steps etc.

Bit worried in bending it too far and splitting... or do I just have to bite the bullet and wrestle the thing out with the filler hose still attached at the bulkhead under the floor?

Also a bit surprised how tight the main lock ring was, it needed Dave's tip of using batten and gentle hammer to almost undo the plastic lock ring all the way.

Any suggestions / tips appreciated

Cheers
Steve

[Rversteeg]

Not sure if running the pump into an open tub would tell you much, as normally it should be able to deliver fuel under 3 bar pressure. In any case, be careful not to create any electric sparks when testing with petrol in the open. If you have a new pump and have the whole lot out of the tank, I would just replace it, especially since you don't fell comfortable about the old one. All fuel pumps seem to fail one day, even the latest, improved turbine type.
I just took all the clips off and removed the hoses from the cover. The large filler hose I moved temporarily out of the way with a strap. I can't remember access from top and underneath was any problem.

Nothing complicated, I am sure you will manage, especially since you are not in a hurry!

[Forrest]

That large hose is the inlet from the filler neck and the small hose that branches off it is some kind of vent. Where the small hose attaches to the tank you need to be careful not to snap the plastic spigot it connects to. I was unable to undo the small hose too and worked around the large pipe by pushing it back towards the vent branch and wedging it up under the edge of the boot floor. It wasn't ideal and it would be much easier if it were possible to get that pipe disconnected.

I wonder on reflection whether it might be possible to use string to tie it back, but I didn't try that at the time.

[TonyS9]

I just bent the flexible filler hose out of the way, but if you want to do it properly then remove it.

I found getting the sender out fairly easy. But you have to get it orientated correctly so it will come out through the inspection hatch, just take your time and try different positions and angles.

Getting it back in is much harder, but still doable if you take the time to get it right. Hopefully you already know you have to compress the sprung holder with string to get it in. Putting this back in blind and getting it settled in the right place is quite hard.

[Steve 940]

Glad I'm not paying hourly rate for this!!!😀

Finally managed to get short filler hose off that makes access so much easier, and what seems ages ago now, I managed to somehow wrangle the old unit out of the tank, trying to picture the twists and turns etc so that putting it back in was a bit easier.

Amazed at how good everything inside the tank looked, the new in tank pickup hose from Volvo was however around 1" longer than what was on there, and after checking the old one over, decided to not change that. Pump and sock swopped over no problem.

Photos show condition of old unit.

Nightmare getting back in, and I'm pretty sure the sock is still on and the unit lines up with the marks horizontal. Cut the piece of strimmer line I used to hold it compressed and I 'think' its sitting where it should.

Anyway, got the unit and seal back in using Forrests guide of seal into tank, grease inner of seal and outer of sender, and it popped pretty much straight in with seal still in place.

Had now around 2 hours trying to get the large plastic locking ring on, tried soaking in hot water, but to no avail.

Have not lubricated the threads at all as I recall Dave had mentioned this was not a good idea and could lead to overtightening.

Suggestions would be most welcome, as looking at the ring thread, it appears to have just one thread and the usual turn backwards till you can feel thread engage is just not working.

If I can get the ring back on I can then hook hoses up, and just route loom to connector and pop fuses back in to double check it all works before finishing off.

Cheers
Steve

[Forrest]

Well done. That must be satisfying to have got to that stage.

The positioning should be right if the sender unit is fully home and the pipes where you attach the hoses are in the same place as they were when you began. What should be happening inside is that the bottom of the pump and the sock should be pointing pretty much straight down into a part of the tank surrounded by plastic baffles. These are there to maintain a quantity of fuel around the pump when cornering or going uphill with a nearly empty tank. If you pushed the sock fully home when you installed it you would have had to have done something pretty special for it to come away inside the tank. It fits on very firmly and has at least one barb to keep it on.

One of the sources I read before launching into doing mine warned that the plastic ring shrinks if kept off the car for any length of time. This was one of the reasons I kept mine on the tank while I strung this job out over the Christmas period. The solution is to warm it up to make it expand enough to fit the thread. I may have been lucky because it was very cold outside when I did mine which would have meant the tank opening would have been as compact as possible compared to the warm ring. I think I just used hot water from the tap (50-60 deg C) but I guess you could use hotter (but not boiling hot) water from the kettle.

I certainly didn't use any additional lubricant on mine other then the water it had been soaking in. This enabled me to get it tight enough to reseal effectively in one attempt. I reused both the seal and the ring, although I had new replacements available. I have also not had to go back and tighten it again subsequently; and I always keep the tank pretty full so I would know if it was leaking. I appreciate that this goes very much against the grain of others' experiences.

Good luck. Sounds like you're nearly there.

[Steve 940]

A tentative success, after 8 hours since flipping the rear seats up to start this simple job, I have now started her up 😀😀👍👍

Main symptom of noisy main fuel pump, has diminished greatly, although a very slight hum now, probably because it's been working so hard over the last months since getting her. Next job on list.

Many many thanks to everyone who has given me suggestions and input on this topic over the last few months, I really couldn't have done this without you reassuring me it was a pretty simple task.

I'll be honest and when I was faffing with the locking ring I was ready to give up, but a cuppa whilst I reheated the ring yet again in water, eventually proved to work, I think!!!

On firing her up, I was firstly elated it started, and then sudden despair as glanced at gauge and no movement, oh ****, seconds later, joy, as I quickly realised I was looking at the temp gauge, doh !!!😀😀. Working fuel gauge as well and indicating same level as when I started @ 3/4 of a tank👍👍

Just as well the tank was only that full, as when I took the unit out, the tank contents were very very close to the tank rim.

Have knocked on the locking ring and clamped it, and will take it for a run tomorrow to double check for any leaks, and route the loom cabling correctly as just temporarily plugged in for now, also as I've disturbed the short filler hose, I suppose best to fill her up to make sure those hoses aren't leaking anywhere??

Will probably keep the access panel off for a few days as I am still not 100% sure if the locking ring is on tight enough, I was hitting it as hard as I dare. Would the fumes be pretty obvious if it needed a bit more tightening??

Well deserved beverage or three later methinks......

Cheers
Steve