fuel tank...what's this

[136388]

My 1997 R850R's fuel pump suddenly went out and I ordered a complete kit from Beemer Boneyard for around $150.00. When I removed the tank I discovered this primer red colored coating on the internal walls of the fuel tank was peeling off.

What in the world do I do now? Is this something to be concerned about and have a shop 'recondition' the fuel tank? I'm at a total loss on this one and there is no mention of the fuel tank's inner-construction in the Hayne's shop manual.

Your comments will be very appreciated! I'm planning on a 5 day trip next week.

[Andy VH]

That red coating is the original BMW coating that keeps the tank from rusting. It is still visible and intact on my 76 BMW R100RS.

But, the fact that it is peeling "could" cause problems for you. One is fuel tank rust, as is evident already. Which likely means the coating will continue to peel as the rust progresses under it. Second, the peeled off pieces of the coating could clog the strainer for the fuel pump. Reduced fuel dilevery and a fuel pump working harder than it should.

Yes, I say you need to get it cleaned out and re-coated. Kreem is one good product to recoat a fuel tank. POR15 also makes a similar product. There was a recent article in Motorcycle Consumer News specifically about refurbishing a BMW fuel tank for this issue. It was an airhead fuel tank, but the product, technique and results certainly apply to what you have here.

[danielroth]

i have had "luck" cleaning these with an hour or so of back breaking work by filling the tank with pool cleaning acid and handfuls of odd old sae nuts and bolts then tapeing the thing up REAL good.
flush and repeat.
don't even try this if your not up for it as this is strenuous and a bit dangerous.

be sure to replace all of the lines in the tank and be darn sure all the clamps are in good shape. wiggle the wiring that runs the pump and be sure that the shielding is not cracking and flaking off.
do not just replace the wires with regular radio shack wire. use the right stuff for gas.
be sure to clear the drain and vent ports in both ends.
also a good idea to replace the big oring and put the proper torque on those nuts.

the bike was likely to have sat around for a while. this is very common in arizona when bikes sit with fuel for more than a year.

i suggest taking the tank to your local independent bmw specialized shop. they will have all the correct tools and knowledge to quickly and safely return the tank to you running.

[88bmwJeff]

You do need to get the tank re-coated as previously indicated. As far as your five day trip is concerned, it depends on how bad the coating is peeling. If it's flaking off in a lot of areas, you probably should get it done before you leave. However, it is not flaking off that much, I think you could wait until you get back. But, I would thoroughly rinse out your tank to make sure all of the loose coating is out of the tank.

Just my $0.02

[stevenmi]

Though I don't know about adding 'Pool acid' to the process, the former post is correct in throwing in 20-30 small (clean) nuts (from your spares collection), then add a quart of fuel (or pool acid), close it up and shake like h*ll.

Empty, clean, and re-line with a Kreem-type product.

This is a job I'd do myself, figuring a shop rate for it would be high just for a labor process. I mean, nothing is technical here. Though some of us can afford to hand it off just for the mess/labor reason, I prefer to save my dealer-$$ for technical things I cannot do.

Have fun. Ride fast, ride safe.

[dougfollett]

My R100RTl airheads tank looked a lot worse than that and I had a eight hundred mile trip coming up. Fortunately for me I didn't know how bad it really was. I just put the gas cap back on and went on my trip figuring that it had run perfectly fine up until now. My luck held and I was able to do the tank overhaul when I got back and had some down time. It's a fairly easy job but takes some focusing in on details. I prefer the Por15. It comes in a kit with everything you need from stripper to primer. I decided to do it myself after I got a quote of $250. When I asked if the external paint on the tank would remain intact the answer was "no". With the Por15 the original paint was not damaged in any way. I did get some of the liner goop on the outside and thought I had ruined my paint job but discovered that acetone removed the liner goop nicely, even after it had dried. Follow all of the instructions religiously and you won't have a problem. It's more time consuming than anything else. A good winter project.

Doug

[136388]

Thanks to all who responded to my question regarding the fuel tank liner. I went ahead and used the Kreem tank liner product with reasonably good results. Just a couple of notes on the Kreem product. I coated the entire external fuel tank with vasoline to protect the finish from the chemicals and did not encounter any damage to the finish. Second, the tank liner needs to be thinned out...it's way too thick to apply an even coat on the tank. Also, a pressure washer helps with removal of the existing liner and chemical residue. Otherwise, a fairly simple process but somewhat time consuming.