Flooding left carb

[Lewes96]

Finally took the bike out for a fast run today and left carb started flooding copiously. Took off the float bowl and full of rusty particles. The fuel in the tank had got quite low and although flushed and cleaned by Motori di Marino in West Chiltington there seems to be more coming through. It has been off the road since 96. Anyway now seems ok but can't help thinking the left carb still has a sheen to it as if weeping fuel slightly. Floats look fine so any other thoughts?

[72degrees]

Float needle.

[smotorboy]

When you have a rusty fuel tank a good fuel filter is in order to keep the carbs from having clogged passages and other issues...

Robert in california

[lambs]

As above, rust particles, etc affecting the float needle tip/seat is the likely culprit. Personally I'd be checking both carbs as they have a common feed from the fuel tap. Probably worth considering an in-line filter - and/or at least a check of the gauze filter at the fuel tap (ie inside the tank), assuming it has one and it's still there (the diagram of the fuel taps in parts book suggests the fuel taps should have a built-in filter, such that it is). The long term solution is to treat the rust as it won't go away.

[3potjohn]

The pin-hole leaks won't be far away. Best thing I've done to a few bikes is to use POR-15 from Frosts. I never get any particles in the fuel pathway. I use the complete kit.Make sure the tank is dry e.g vacuum cleaner on blow, before the final addition of the sealant.
I have in-line filters on the Morini which is however against my philosophy as any muck or water could cause a starvation effect.
John

[MickeyMoto]

Check filters in carb entry.
Check float height
Check float bowl gasket

[lambs]

Check filters in carb entry.

Good point. I forgot that the carbs on these bikes are essentially identical in this regard to the carbs on some Guzzi's, Laverda's, etc. If the stock filters are in place and in good nick there should be no need for an additional in-line filter.

[72degrees]

There are fine filters under the carb fuel banjos and on both taps. If the banjo bolt washer is damaged, or the bolt not tight enough, you can get a weep from that area.

On both my 2C/375s I use an in-line filter in both fuel lines. I'm not bothered about total originality and the glass/stainless ones that NLM supply provide a very rapid visual early warning of any build up of clag. No problem with starvation even with PHBH28s.

I have had to replace a float needle once as the tip had become grooved and it wouldn't seat properly. To be fair, that resulted in more than just a 'sheen'.

If the tank has been left only partially full since 1996 I suspect you may ultimately have to line it. Another vote here for the POR15 treatment.

[EVguru]

Unless you actually have a pinhole in a tank, or know you have heavy corrosion, I'd steer well clear of tank linings. You hear of many more problems with flaking, peeling, or disolving tank linings than you ever do about leaking tanks. Over the years all the various lining systems have claimed to be compatible with pump fuel, but they will keep changing the fuel formulation.

I've removed rust by first using a caustic soda solution to remove fuel varnish, then Hydrochloric acid and a final Phosphoric acid treatment to stabilise any remaining rust. Miniature USB cameras are pretty cheap these days and will allow you to inspect the far corners of a tank.

On my 250 2C all those years ago, I did more or less nothing with the rusty tank, other than giving it a really good wash out. After a few tanks of fuel I stopped getting significant amounts of particles through and in the meantime, I just dropped the float bowls regularly.

Don't forget that sediment will accumulate in the carburettor link pipe.

[penman]

I must support Paul's posting because it is exactly my experience. In recent years I have been advised over and again to use a tank lining as a "precaution", to protect the tank before it starts leaking, and it sounds reasonable. Except that I've also spend literally days trying to get rid of decaying linings. We are not talking about fuel strainers being clogged by rusty particles, this is sticky lumps which will block pipes and taps - and you need very aggressive treatment to get rid of it. The caustic soda, followed by hydrochloric acid does a good job on a dirty /rusty tank and unless the tank is actually leaking, I would tend to leave it at that. All fuel is hygroscopic to some extent, you can't just blame it on ethanol, so if the bike is to be laid up for a period, it's a good idea to drain the tank and dry it out with warm air - OK, that sounds a bit obsessive, but it's only half an hour's work, the fuel you drain can go in the lawn mower and your tank's safe.

[72degrees]

Agreed that best not to line a tank unless pin holes have actually developed. In my experience, however, when that time does come then POR15 does what it says on the tin if the preparation and curing process is followed correctly.

[Lewes96]

Thanks for all the replies. I am going to investigate the needle first, then the inside of the tank and filters. These are in place on both taps, just need to check the condition and go from there.

[Lewes96]

Cleaned both carb float bowls and the issue seems sorted.