weird eiger fuel problem... - Suzuki Z400 Forum : Z400 Forums
 
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post #1 of 7 (permalink) Old 02-25-2014, 04:07 AM Thread Starter
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weird eiger fuel problem...

Hey all, got a weird problem with a friends 400 eiger.
It happened all of a sudden after it was left in the shed for a week, the bike is used as a spay vehicle for grapes so it kind of needs to get back to good running order soon.

The problem is that is appears to be running very rich.. its hard to start and will only start when full throttle is applied and it still takes a while.

The weird part is that when running the engine with the fuel tank removed and with only the fuel in the fuel bowl it runs like brand new.

I have checked the petcock (fuel valve) and that appears to be working correctly ie. fuel only allowed threw the valve when a vacuum signal is present. apart from when valve set to "pri" I assume that setting is for priming the fuel system??? i could be wrong tho.

I have removed the carby and cleaned all fuel passages and checked all jets, the float level and all gaskets and o'rings for good seal. Ive got nothing wrong with the carby.

The other thing i noticed when pulling stuff apart was that there was a lot of fuel in the air filter box. I'm unsure if the fuel found its way there while i was checking the fuel valve or if its a symptom of the problem.

Any help would be awesome, i'm a engine tuner, engine builder and light vehicle mechanic by trade so 'im not confused by engines and the surrounding systems, but my experience and knowledge of small single cylinder engines is obviously lacking.

cheers Sam form Australia.
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post #2 of 7 (permalink) Old 02-25-2014, 07:49 AM
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Hello,
My suggestion would be remove all the fuel out of the air box and see if the air filter is clean. A dirt filter would cause a little bit more fuel go into the engine than normal. Then see if it still starts hard. That is where I would start.

Good Luck, I hope you get it running again.

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post #3 of 7 (permalink) Old 02-25-2014, 11:12 AM Thread Starter
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hey, cheers for the input, it defiantly has nothing to do with the air filter. Ive ran the engine with and without the air cleaner fitted.. and the air box cleaned.

I dont know if i mentioned before ( a few beers were drunk) but i can get the engine to run beautifully when the fuel tank is not connected to the carby. If i fill the fuel bowl and run the engine with the tank disconnected it runs perfectly.. as soon as i run it with the engine connected it runs terrible.

cheers sam
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post #4 of 7 (permalink) Old 02-25-2014, 03:54 PM
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Did you try to run it with gas cap off tank
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post #5 of 7 (permalink) Old 02-25-2014, 04:40 PM
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Quote:
Originally Posted by Sparksz434 View Post
Did you try to run it with gas cap off tank
I've had that happen to my old dr350. The gas cap got clogged somehow and it left me stranded in the middle of the woods on a short ride. Although this would make the engine run to lean, it is worth a quick check. Another thing to try is to run the fuel valve on PRI. PRI just lets fuel run out of the gas tank without a vacuum needed. The ON position needs a vacuum to let fuel run out of the gas tank. It is possible that the vacuum line is not letting air flow through as well as it should. Again that problem would make it run to lean, but that is all I can come up with right now. Let us know how it goes.

Again, Good Luck!

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post #6 of 7 (permalink) Old 02-25-2014, 05:07 PM
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Sounds like a bad needle & seat. Or at least one that's leaking at times. That's how it gets in the air box for sure. I would get a new needle & seat, and also make sure you check the oil. When a carb runs over, often times gas runs down the intake, on to the piston, and leaks by the rings, down into the crank case.

I have fixed many things with this symptom and found exactly that.
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post #7 of 7 (permalink) Old 03-06-2014, 06:16 PM Thread Starter
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hey all, thanks for the help.. i work away a week at a time and have no internet so i couldent reply earlier.
Yes i have tried running the engine when the fuel valve is in the PRI setting.. no diffrence..
i have also pulled the carby apart and checked all the jets, needle and seat.
Apparently this problem happened after the bike was serviced by the local small engine mechanic in town, as there are a lot of quads used at all the wineries around he is usually very good. He has had some problems lately and as a result his game has slipped ( it happens to us all )
Im going to put the carby back on the engine this weekend and hopefully it is running sweet.
So ill let you all know how i go.. but i suspect it is going to be a hairy problem. I will try running it with the cap off and see how it goes.. that is something i didnt think of..

chees sam
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