Over fuelling?

[jai1]

Hi Guys!

Have a bit of an issue with the MB at the moment.

Has been running fine for 6 months and then as of Friday it started really coughing and spluttering on the way home from work (about a 20 minute drive @ 60km the whole way). Just made it home and it died in the car port. Really smelt "fuelly".
Anyway, Saturday i took the air cleaner etc. off (which had some fuel sitting in it) to have a look at the carby and it seemed to have a white "jelly" stuck on parts of it. Thought it just needed a clean so used some Carby Cleaner on it all.
Ran sweet again for 2 days and then yesterday the same thing.

Interesting thing though is on the way to work it ran ok 80% of the way then started surging etc. again. Got in it last night and again it was fine 80% of the way home then same thing.

I have bought some new plugs and leads and a new air filter (since the other one was sitting in fuel) but haven't had a chance to do the leads/plugs yet.

Any ideas appreciated muchly!

[Al_Zhiemer]

I'd be going back to where you got your last batch of fuel from to begin with, sounds like you got a bad batch of fuel. Possibly because their tanks were so low when you filled up.

Check all your fuel filters, should only be the one but i have noticed on both the MB's that i have that there is 1 filter in the engine bay and another located near the passenger side rear wheel arch.

Might not hurt to drop the fuel out of your tank and check how clean it is as well.

Cheers.

[Brayden]

Problem sounds like a clogged fuel filter or dirt in the float bowl.

[jai1]

Cool thanks.

Funny you say about the fuel as I did just fill up last week...

The fuel filter is only about 6 months old but for the cost of one I can replace again to be sure.

Some one else mentioned the "needle and seat"? Is this something to check as well?

Thanks!

[Brayden]

Yeah definitely. At the first sign of fuel trouble I always strip down the carby and inspect/clean it.

[Al_Zhiemer]

Possibly needle and seat problem but doesn't explain white "jelly" substance in the carby, it was in the carby right?? Is this still happening??

But it may have something stuck in the needle and seat which is now causing it to over fuel.

Would personally be exploring contaminated fuel. Not sure if just replacing the filter is going to solve the problem as what ever is getting in to the carby is flowing freely through the filter already, unless the filter has a hole in it.

Seems that it may be denser than the fuel once it has gone through the carby and is sprayed in to the inlet manifold as a mist, thats when the foreign matter is seperating (at a guess anyway).

Its the white "jelly" substance that has me beat as i have never seen or heard anything like that in a carby befor or have any idea what may be causing it.

Keep us informed on what the out come is.

[Ralf the RR]

Can't explain the jelly, but I've been having more carby problems with my MB.
Seemed to run for 15-20 mins and then lose all power.
Pull over and let it idle for a couple of mins, then give it a rev, and all is OK for another 30mins.

Turned out to be carby icing.
The tube from the exhaust to air cleaner was missing when I bought the car.
$12 for a hose and no more problems.

[Brayden]

The mystery white jelly is likely to be oil foam from the PCV system. The pipe from the rocker cover bypasses the filter and drops straight down the throat of the carby.

[jai1]

Ok, have had another chance to pull the air cleaner etc off again tonight.

Brayden seems to be right, there is also "jelly" or oil foam on the spigot on the rocker cover with that hose removed.

Inside the throat of the carby it is back again! Only on the front throat, not the back which makes sense as that is the side the hose enters on.

Is this the issue, or a side effect/differnet issue?

There also doesn't seem to be as much (very small amount really) of fuel in the cleaner box this time.

With the comment about the hose missing from the exhaust to the air cleaner, is this the hose that should enter around the same spot as the winter/summer switch? If so, mines missing as well!
I have the F8B engine and not knowing all that much about it all thought this must have just been something not needed on the larger engine. If people are laughing reading that then i am probably wrong....

[Brayden]

Yes that's where the hose goes. If you install the hose and flick the switch to winter, the engine draws heated air off the top of the exhaust manifold. (assuming you also have the flange installed on the exhaust manifold too!)

[jai1]

From memory i don't think i do. I think that is why i assumed it wasn't required on that motor as i couldn't find where to plumb it to.

Although the car has been running fine so far all winter and now this....

Is this hose or the oil foam the issue? Or are these just other issues to deal with?

Probably won't get a chance to pull the carby apart till the weekend to check it out. Is it worth getting a carby kit for it? I believe the carby was "kitted" not long before i bought it (in Jan).

Also, not being 100% knowledgable on all this yet, is their a guide or anything to pulling the carby apart and what to look for and clean?

[Brayden]

Also, not being 100% knowledgable on all this yet, is their a guide or anything to pulling the carby apart and what to look for and clean?

No, but that's a good idea! I should put one together - maybe this weekend.

The oil foam could simply be condensation forming in the motor overnight. If it is only present in the carby in small amounts then it should burn off, assuming your secondary throttle is working properly. It shouldn't accumulate in any great amount.
If the foam also appears on the dipstick, then you have real problems.

In my experience the "winter" hose setup isn't necessary, in Canberra the temp gets down into minus territory during winter but I've never had a problem with "carby icing". Mind you I do let the engine warm up for 5+ minutes before driving.

[jai1]

No, no foam on the dipstick so thats all good. It's not heaps in the carby but it must happen every day as i cleaned it and then it was back.

If you do get a chance to do a guide that would be awesome otherwise i might end up putting it back with more problems than i started with!

It sounds like this will be the next thing to try though pulling it apart and cleaning everything.

Is the carby kit required (for seals or anything) if i'm taking it apart?

I also let the car warm up for 3-5 minutes before driving and it is in a locked garage every night so it never gets as cold as outside.

[ceej]

Much agreed with Brayden and the Canberra climate not having much of an effect in the winter on the carby. I have a pod filter induction setup going straight behind the headlight and I have not had any problems with carby freeze. And it get farking cold here!

I also back up the claim of blow-by being the cause of your "white jelly". When I get blown I produce the same sort of stuff! I mean... err... the ute does the same, though I have an oil catch can setup to catch it. When I used to just have a filter on the top i could sometimes see the foam on top of the sponge filter element.

[Brokenshire]