Had the pump assembly out to change filter and check the condition of the hoses. All good, nice easy job and the inside of the tank is squeaky clean however I’ve put it all back together with a new o-ring and I’ve noticed a gap between the mounting plate and the heads of the retaining screws. Is this correct? O-ring is fully seated as far as I can see and the screws are fully tightened down.
Did insertion procedure with “O” ring go smoothly? No massive force required on one third more than another? The gap is even all round? It looks fine to me, but I guess you could do a leak test before fitting if you felt like going to the trouble of plugging up the feed and return hoses etc.
Installation went pretty well in my view but this is the first I’ve done. I think a leak test may be in order. wish I’d paid more attention before I took it all to bits
I bet all is fine, I remember the first one does feel like a lot of clamp-age to get it home, but I’m sure you checked the O-ring all round as you slowly clamped it down? and as it finally disappears, as long as it doesn’t squirm anywhere around the periphery as it finally goes in, then it’s absolutely fine.
There are no washers under mine but there is also no gap between the plate and the bolt head when all tightened down. The 'O' ring sits internally so doesn't affect the gap but I'd like to see the pump flange be held to the tank if it were me. It doesn't need to be held at any particular torque/tension to get a good seal but if it pulls away slightly it might let the 'O' ring move enough to leak? Assuming it doesn't leak, I'd be looking at fitting suitable washers or even a bolt with a shorter head - are there different thicknesses of base/flange and, if so are they the correct bolts?
If I remember correctly, the hole in the tank where the pump goes has a formed flange on it. The flange has a slight curl on it which is where the O ring sits. As the pump gets pulled down by the bolts, depending on the tolerance of the formed flange, the pump O ring will go past the smallest diameter of the flange and naturally sit in the slightly larger curled part. This can mean that the pump flange sits further in to the tank aperture and beyond the fully tightened bolts. I think this is the situation you have. In my opinion, it should be fine as I have had seen it on a couple of my tanks before and they didn't leak. I hope this makes sense.
Thanks Ricky, makes perfect sense to me and I think that's what is going on here. As the shoulder on the bolts are taller than the material thickness of the mounting plate the plate can never be in contact with the bolt head and the tank flange at the same time. Leak test when I'm next in the garage but feeling like this should be OK.
@Dukedesmo, I think the bolts are correct, they check appear the same as the listed parts online and going by the age of the fuel filter they've been in there a good few years.
and don't forget, standard fixings are ok - the "O" ring sealing correctly does not rely on the fuel pump flange assy making full contact with the tank mounting face, as long as the two faces are totally parallel- i.e. any gap visible is equal for the 360 degrees of the flange that's visible then correct sealing will occur as intended.
Probably so, I doubt there are differences but my OCD wouldn't let it sit with that much gap - can't hurt to stick some washers in.
Make sure the thread under that bolt is clean. The fuel pump requires that bolt/screw to be tight on the flange or it may wiggle loose and cause a leak. I assume you used a brand new seal around the base as the used ones are always a tad too big and will catch on the way in
the choice is your re: new seal - have re-used mine many times, they nearly always shrink back down when left for a day or so, even hot hands will cause swelling, a spell in the fridge prior to fitting helps.
I've re-used the 'O' ring before, as above they shrink down after a few days and work OK (I've never had a leak) but recently I found a supplier that sells the correct sized Viton 'O' rings for a fraction of the Ducati price, I bought a job lot so it's not worth even thinking about it any more.
I got them from Polymax; https://www.polymax.co.uk/o-ring-117-07mm-id-x-3-53mm-cs-fkm-viton-75-sha Part no. BS247V75, currently £1.04 each for small quantities. I think there is a minimum order of £10 (ex. VAT) but with that you get free UK shipping so I bought 12 which, (at my age) will probably keep me going for my lifetime...
Indeed, 12 for the price of 1 from Polymax. Even cheaper if you buy in bulk, though I considered 12 will keep me going for as long as I need, given I probably only change them every 3 - 4 years and I highly doubt I'll be riding bikes (especially a 916) in 30+ years time...
