Crap in fuel tank - some sort of resin like substance

[Nipedley]

Hi guys,

I've been chasing a fuel starvation issue on my GS500 for a while now. She runs perfect at any rpm and at any speed, until you go over 70 mph for over 25 seconds or so, and then what I presume happens is the float bowls are draining faster than they fill up and she chokes and coughs and splutters until they catch up again.

First I cleaned out the carbs, all good, then I cleaned the fuel tap, all good in there too. So I thought I'd drain the tank, clean the filter etc. Drain went fine, filter was pretty clean for a 25 year old bike and also fine, then I go to move the fuel tank and hear a load of clanking.

There's bits of this stuff in there ranging from finger nail sized thin pieces, to a massive clump of it that knocks around inside that is probably 8x8cm and about 4cm thick - clearly none of this stuff is doing any good. I got a lot of it out by shaking, but some is larger than the fuel cap hole and will never come out and I don't want to spend eternity shaking my fuel tank. Is there something I can put in that will disolve this crap and then I can flush it out with something? Also, any idea what it is?

TL;DR resin shit in fuel tank how can I get it out

Many thanks!

[Amber Phoenix]

Probably some kinds of tank seal to fix a leak or just tackle rust.
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[Az]

Why don't you just fit a fuel filter instead of cleaning out the tank?

[Nipedley]

I just fitted an inline fuel filter, and the tank petcock has a filter on it that will stop this stuff getting through, but I'd still like to get it out.

I seem to have ruled out all other possibilities for my high speed fuel starvation, perhaps that massive clump of it is sitting on or near the tank petcock and blocking it

[Robby]

It does look like an old tank sealer. Instructions for getting rid of it, and then de-rusting the tank if necessary, are here: https://www.realclassic.co.uk/techfiles/petrol_tank_cleaning_and_rust_removal.html

I've de-rusted a good few tanks, the method there is the best and cheapest one that I have come across. Just bear in mind that strong acid will attack aluminium alloy, so remove the fuel tap and cap.

[-]

If a bike is stood for years, the fuel in the tank evaporates eventually into a varnish. If you can trace the mot history, it might explain it.

I don't know what Petseal looks like, but have heard similar stories to yours. I've always used POR15 as a tank sealant and this looks like a thick silver paint.
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[Nipedley]

[mudcow007]

could you not just make a blanking plate (for where the tap goes) from a bit of scrap metal, use a cardboard gasket. that's what i used when i sealed my tank