[meridianfrost]

1996 Thunderbird 900 1350 miles

Ok, this may be a little wordy, but I hope that someone else has gone through this, and can help.

Last week I decided to put some sea foam in the tank to help clean the carbs from their winter slumber. I have run the bike every week, and it has always started right up without any problem. The next day, I decided that I would drain the old gas, and put in a gallon of new. The bike started right up, ran for about a minute, and gradually the rpms started to decline, and the bike stalled. I tried to start it again and again. Occasionally it would sputter, but did not start again. REmoved the battery to charge it.

I know I know. Gunk in the tank has blocked the petcock screens.
Nope.

Seafoam dislodged gunk in tank, and clogged in line filter.
Nope.

Bike somehow miraculously lost spark.
Nope

Fuse is blown.
Nope

All silly stuff, is it in neutral? Yes. Is the side stand switch operating properly? I dont have a clue. Dont know how to use a voltmeter.

Here's what I have done:
I removed the tank, and took a look at the fuel system. I didnt remove the float bowls on the carbs. I checked all lines, and momentarily thought that the roll over valve could be malfunctioning, causing vacuum lock, removed it, still wouldnt start.

I removed the in-line fuel filter and replaced it. Still wont start. Gasoline flows freely through the petcock on "ON" and "RESERVE" valve settings. I know that gas is getting where it needs to be, but it wont start.

I am at a loss. The only thing that could have happened is that it isnt getting air because overnight a mouse crawled into my airbox. Highly unlikely.

The only other thing I can think of, is that while sitting, a colony of ants decided to make my fork and battery storage box a colony. When I started the bike the previous day, It sent them scurrying all over the bike, carrying little eggs in a frantic bid to escape my thundering motor. Could ants have made their way into a critical spot on the bike? I dont think so. And in any case, the bike ran fine before I drained and refilled the tank. As I said, gas flows freely through the petcock. Also, it is worth mentioning that I cannot remove the plugs. I have all sorts of plug sockets, and none of them fit. It is very odd, but I cant get em out. So I havent checked the plugs to see if they suddenly became so clogged up that it would cause them to lose spark (I checked for spark with a new plug). I have no idea, and I am losing my marbles. Any help anyone can offer would be greatly appreciated. Thanks again.

meridian

 

[Tbirdnz]

Sounds like petrol starvation, carb jets blocked, I'd look at them first, you could have dislodged gunk into them.


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Ride on !

 

[buxtonmick]

I'm with Tbirdnz - the gradual decline in revs that you describe would be the jets becoming jammed up (most likely the minute bores of the pilots) either with gunge freed by the Seafoam or rust from the tank. From what you say about the plugs the bike sounds like it may not have been maintained very well; it has certainly been stood quietly decomposing for some time looking at the mileage!
The carbs will have to be stripped down and cleaned extremely thoroughly at least once, paying particular attention to the jetways and jets but check the conditon of your tank's interior - if this is rusted then you're wasting your time cleaning the carbs without sorting it out. For the plugs you'l need an 18mm thin wall socket to get down past the valve cover seal. Best of luck, Mick.

 

[ssevy]

Fuel filter condition

The petcock and duckbill filters remove sediment of a certain size, but unfortunately, the smaller stuff passes through and takes up residence in your float bowls and pilot jets. It does not take much to really plug things up. You may as well learn to remove the carbs and clean them, as I have found this to be the most common procedure on my Legend (at least until I can get my Caswell tank sealer job done and cover up the rust in my tank). Bottom line: clean petcock and duckbill filters are no guarantee of clean carbs, especially if the bike has sat for awhile, as the once fresh gas in the float bowls themselves can break down and get nasty, regardless of what is coming down from the tank once it gets restarted in the spring.

 

[cafetbird]

I also support the popular opinion here. You should pull the carbs and clean them thoroughly. Pull the pilots out completely and clean them. With that low a mileage, the bike has most likely collected some gunk in the bowls over its 13 year life.

 

[faffi]

When you say you know fuel is raching the carb float bowls, is that because fuel is running freely out the drain pipes? Sometimes, for reasons I dont fully understand but have learned to accept, fuel can vapourlock and the floats simply won't fill.

Regadless, a complete carb clean sounds like a good place to start, if for nothing else than preventive maintenance.

 

[meridianfrost]

thanks to all for the advice

I have worked on the bike all day, and it is running. I removed the petcock, and recognized something that I hadnt when I had it off the first time. The reserve screen sits a little below a rubber gasket, and is basically enclosed in a metal sheath. For some reason, one of the little plastic supports on the reserve screen was inwardly bowed. Turns out (to my great dismay, and embarrassment) that the metal sheath comes loose. It was so clogged with crap that I thought that it was a solid piece. When I finally freed it up, there was an immense amount of grudge built up on the screen. While it was true that gasoline was coming through the petcock on reserve, it apparently was constricted so much that gravity couldnt do its thing, and the flow just was not enough to keep the bike running. Bah. Cleaned it and it fired right up. It is still a little sluggish, so the carbs still need to be cleaned most likely, but it is ridable, and that is the extent of my concern for the time being.

Alos, I found the tool kit that came with the bike, and it has a spark plug spanner in it. Doh! I pulled the plugs, cleaned em up, and threw em back in.

Thanks to all who responded. I really appreciate your help!

meridian

 

[Tbirdnz]

Glad you're up and running, thanks for the update.


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Ride on !

 

[ssevy]

Glad you found it. If there was a hall of fame for missing things while doing maintenance, it would be the largest building in the world, and I would definitely have a plaque somewhere! We have all "been there, not done that"