Bonneville America Forums Forums Technical Forums General Tech Runs like crap - fuel starvation?

Well, first it was the bad tank of gas I bought, then the plug wire to the coil shook lose. Now its just intermittant crappy -loss of power-feels like its out of gas-gonna die behavior. Some backfiring and RPM surges when you stop throttle. I searched the archives and found a bunch of clogged petcocks/filters, where should I start?
I hate to wrench on Charlize 'cause I'm sure I'll scratch her. I added Jims Spacers and caught the fender with the drill bit -yikes (still can't believe BOTH nuts stripped).

thanks in advance,

Custus

Hi Custus,
How many beers from the top yoke to the fender, there bud?
I think you need to synch the carbs, but other problems may exist. Be patient and wait for a reply that rings your bell, then start there. This site has many sages that I respect. One will be along soon enough.
Are you talking about full throttle at high RPMs? Maybe you're reaching the rev limiter? Could be the hidden mystery filter in the fuel line "T"? Keep searching until you find it. Once you acheive your balance (back to synching carbs) your Triumph will run like a dream.
Ride Safe,
Dennis

Sounsa like you have a vacuum leak. Check that all your caps are on and don't have little cracks in them. Then pull the mystery gas filter and clean it.

Custus, sounds like we have same problem, here's what I've tried:
checked all vacuum leaks with ether --OK
new pick up coil-- not it
new ignition coils-- not it
checked both petcock and inline fuel filter-- both clear
tore apart and cleaned entire fuse box-- not it
experimented with jets -- nothing
checked float level-- good
eliminated sidestand switch-- not it
dielectric grease on all connectors in 30 amp circuits-- not it
checked needle wear-- ok
I think thats it but im sure i forgot some tests i did so if you find anything keep us posted good bloody luck

I had a similar problem. After I reseated all of the electrical connections, including the coils, the problem vanished. Might be simplistic but it worked for me.

Custus,

Try dropping your main jets, the main jet holders and the collars. Ensure the main jet and each main jet tube holes are clear. One problem a member had was his Main circuit not having a collar. Make sure both your main circuits have this collar.




Regarding what Benkolb wrote about his troubleshooting, I too had the same problem. Once when Vera was new and once after I used cotton.

The carburetors were plain dirty re the first occurrence. A piece of cotton was obstructing the right carburetor’s main jet the second time (after going nuts trying to find an electrical problem much like Ben has done). The first occurrence speaks to the need to not only remove and inspect the jets, but to also blow out the internal passages of the carb. You might want to pull the tops off and examine the slides for debris and the needles. Heck a complete dismantling may even be in order. Any stuff in those passages will obstruct the fuel/air flow enough to give you that “intermittant crappy -loss of power-feels like its out of gas-gonna die behavior”

Be real careful removing the air mixture screws. Little o-rings, washers and springs.

Archived quotes:

Chy:

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Is it a stumble type feel or more like a "fish Bite"? If it's a stumble or fade at speeds, it's likely fuel related.. if it's more of a jerky sensation, it's likely ignition. If it is secondary ignition (coil, wires, or plugs) it would likely do it under load (low RPM, hard pull). Since the engine isn't under a real load at that speed you may have a problem with your primary ignition circuit ( pick-up, throttle position sensors or igniter module). I'm leaning more toward the fuel system from your description so you might try loosening the gas cap (weird little check valve problem). Also, have you tried pulling out the choke a bit when it's doing it? If it goes away or gets better, it's fuel related. Hope some of this rambling helps.

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Greybeard:

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A really cheap neon type timing light will tell you if it is in the electrics. Hook it up, tape bungee or somehow place the light so you can see it, and take a look when the engine starts missing. If you still have a nice steady flash and the brightness doesn’t change, the spark is fine. If it gets a little brighter, the sparkplug is shorting or fouling. Try this on both sides because Triumph uses 2 coils.

If it’s a fuel flow problem, the bike will run fine until the carbs run low on fuel, and it will run fine again for a while if you slow way down, coast or stop long enough for the float bowls to refill. When it first starts having problems, a little bit of choke will usually help for a while.

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Redondo Ron's: A Carburetor Primer

Thought of a couple of other things I did. The first being to dissassemble the carbs and used a little can of air from a computer store to blow everything out and I actually found a paint chip in my main jet holder (have no clue how it got past both filters) but that made no difference anyway. I also eliminated the check valve on the end of my fuel overflow tube -- no change. Took it out 80 miles today and I think the ignition coils were the problem because electrical cutout seems to be gone now it did it only at idle and after I coast down a hill then get back on it. So I think my jets are just screwy now from where I was experimenting. For three years I ran 42\132 with drag pipes no snorkles now Im at 45\150 (because the cutout made it act lean) so I think mine may be cured when I get some time to get jets back to normal. Only problem is now I have to spend a month at Betty Ford clinic from all the beers it took to work through this.

Plus double check your battery connections. Several months after i bought my TBA, it was losing power upon acceleration. I would crack the throttle and you could just feel the lack of power. I know it sounds unlikely, but i remember reading somewhere (probably here) to check battery terminals. When I did, they really didn't look bad. I could move the negative terminal lug, but it wasn't loose or too easy. It was essentially tight in my opinion. But, I wire brushed the terminals and reconnected the battery. The difference was immediate, it ran great. However, mine did not backfire nor surge. But these electronics don't like bad grounds, etc.
Jay

Whoa, thanks jay I cant believe I didnt try the most obvious first. That may not have been my problem this time but it has been in the past and I'm sure it will be in the future. Oh well as long as I keep finding things wrong with the bike I can suck down 12-packs of problem solvers out in the garage.