Fuel starvation problem?

[97tiger885]

I bought a '97 steamer with 28k in May.  It has a stalling problem  It begins to stumble and then stalls.  I have power to the gauges the entire time.  It does this with a full tank, a nearly empty tank,  at highway speed, at low speed, in cooler and hotter temperatures, 3 or 4 times in quick succession and not for 250 miles. After 5k, the one thing I have determined is that if I switch to the reserve pipe when it begins to stumble the mc recovers.  The mc then runs fine when I switch back to the high pipe until the next time.  I have eliminated the following: Coils, as the mc stalls; venting, as I have snaked a wire through the gas tank vent, replaced the one-way breather valve, and run with the gas cap open; Ignition sensor, as I have replaced that with no effect; and Petcock, as I have replaced that with no effect.  My last guess is that the stock in-line fuel filter is clogging.  Anybody have any similar experiences with this?  Is it possible to remove the stock in-line filter without removing the air filter and carb assembly?  (Brilliant placement of that filter.)  I have put in an in-line-off-the-petcock fuel filter and plan to toss the stock in-line filter when I can manage to reach it.  Anybody else doing this?

[Mustang]

John is this you  ?

Sounds like the inline filter is clogging , but it could also be just the plain stupid way triumph routed the fuel hose , it works much better if you run it down under the carbs rather than up over the top . you have to buy a new pc. of 5/16ths hose from the auto store and at the same time you can get rid of the inline filter btween #2 and #3 carb just the aftermarket filter instead .
And if it's any consolation my wife's tiger needs to be switched to reserve from time to time with the same syptoms .

[BR]

97tiger885,

A couple of things...
Tank Vent.  If your bike was orig sold as a non California bike (ie, 49 state), then you likely have just one vent fitting at the bottom right of your tank?  And that should be your tank overflow from the gas cap filler neck.  I'm wondering, do the non-CA bikes then vent thru the gas cap?
Inline Filter: if you have the OEM fuel line (it's pre-formed, goes over the carbs) then you might be able to remove it without yanking the carbs.  The little filter is inside the hose near the end where it connects to the T-fitting on the carbs.  Just yank it out and toss it.  I moved my carb T-fitting from between carbs 2/3 over to 1/2 just for easier access and hose routing.
Coils:  you say you eliminated the coils?  They might test good but they can still give you trouble. Replacing them with the Nology or late model Triumph coil sticks is the best way.  Do that and then you can forget about them.

Regards,
Brendan
'98 BRG Tiger, (CA model)

[Dr. Mordo]

If you can fix it by switching the fuel 'supply', then it certainly has something to do with the passage of fuel between the valve inlet and the intake manifold.  

I would certainly pull the filter, but I am sure Mustang has done that to his wife's bike, so it may not be the problem.  You do have to pull the carbs to remove the stock inline filter.    

I might also pull the fuel valve and try pulling the sock filter off of the primary inlet tube.  Mine was clogged and I pulled it and cleaned it, although as I recall the reserve inlet was worse.  However, the valve itself was bad so it all got replaced anyway.  I don't think you need it with an inline filter; I'd just pull it and set it aside to see what happens.  You don't have to drain the fuel if you set the tank on its side, but don't smoke a cig while you're doing this!  I know you replaced the valve, but maybe it's clogged again?  Maybe you need to flush the tank?

I can't imagine that any part of the carb could be the problem, unless the infinitesimal difference in pressure due to the lower reserve fuel tube could make a difference.  Sounds pretty unlikely to me.

What does it do if you run on reserve all the time?  Mustang, what does your wife's bike do if you run on reserve all the time?

[Mustang]

Her 95 is bone stock and she doesn't let me modify anything on it . :shock:
her bike in the hot summer days , when she has been riding awhile , (fuel level doesn't seem to matter) will act like it is running out of fuel , and switching to reserve it will come right out of it , she doesn't even pull over to the side of road . After a few minutes she will put it back on main pipe and bike will continue to run fine . this only seems to happen when it is warm out IE mid 90's for air temp .

I am convinced it is the way the fuel pipe is run to the carbs  ...BUT she don't let me modify  anything on her bike , it took me forever to convince her to try Tourances instead of those shitty T 66's for tires .(she's a stubborn Maine girl )  

I ran my fuel line from the petcock straight down to an inline aftermarket filter and then the fuel line goes under the float bowls to the "t"  between #2 and #3 carb , fuel flow is much better this way and when all 3 carbs want a drink at once , one is not waiting on the other to finish .

With the stock triumph fuel pipe set up I can almost gaurantee that one out of three carbs is waiting for fuel to be available . Like when you run onto reserve , usually one carb runs out of fuel before the other s do .

rerouting the fuel pipe made a huge diff. on my 98

[JetdocX]

Mustang, your wife's steamer fuel problems sound a little bit like vapor lock.  

A re-routing of the fuel line could possibly solve that.

[Mustang]

read the first sentence in the above post of mine  

and the friggin thing is never home long enuff to work on anyway !

[Dr. Mordo]

97Tiger885, clearly you need to re-route the fuel line.  If it fixes the problem, Mustang can lord it over his wife that he's been right this whole time about the fix.

[cascadetiger]

I had a stumble, bad running, 2 or 3 cylinders problem last summer on my  98 Steamer, had 20,000 miles then.  I took the fuel filter out and cleaned it.  There was a minute black particle in it.  Put it back together and the bike ran perfect.

The filter is a pain to get to.  It can be reached without taking the carbs off.  I call the filter a "mouse condom".  Its very small.

[97tiger885]

Thanks for the great advice.  Rode it to Vintage Days.  The problem gets worse with heat.  At lower temps, the switch to the reserve inlet immediately cures the problem.  At higher temps, it takes some time for the engine to recover.  And at really high temps, it might not recover without pulling over and restarting.   I have emptied the tank a few times and the gas looked fine.  But I didn't use anything to rinse the tank as I have no experience with plastic.  And you can't see or reach into the tank for check for gunk.  Any recommendations on cleaning the inside of the tank?  The coils have been replaced with the Noxology product.  My plan is to reroute the line underneath the carbs and discard the filter.  This may take a while as I hate to fiddle as long as the mc is running.   My mechanical fixes tend to create as many problems as they solve.  I'll let you know how it goes.  

Having lived with this machine for a few months now, I must say it really is a fine bike, especially for my style of riding.

+++++
Jon

[97tiger885]

I lied.  I went ahead and fiddled.  Sorry Ken, rerouting the gas line had no effect.  I did not remove the OEM filter.  I now have a new theory.  The primary intake on the petcock has a long tube with a screen filter stuck on the end.  The reserve intake has a very short tube which is only long enough to attach the filter.  I am now thinking that the heat is causing a vacuum in the primary tube which is drawing in gas so quickly that it is collapsing the filter screen and that the screen is fine enough that doubling it cuts off the fuel flow.  Switching to reserve cuts off flow to the primary intake which allows the screen to "re-inflate".  The reserve screen is not collapsing because there is no tube and gas flow is never exerting enough pressure to collapse the screen.  I have removed the filter screen from the primary intake.  I will let you know how it goes.  

+++++++++++++
Hoping that in-line filter I bought works,

Jon

[Mustang]

Keep us posted on what you find cures it . Because the wifes 95 does exactly the same thing but she is quite content to just flip to reserve for awhile . It's been this way for years ! :shock:  

[97tiger885]

I now have 225 incident free miles.

+++++++++++
Jon

[Mustang]

I wonder what Triumph changed here because my 98 has never not once had this problem , the wifes 95 has been like this since as long as I can remember .

[JetdocX]

I wonder what Triumph changed here because my 98 has never not once had this problem , the wifes 95 has been like this since as long as I can remember .

95's have Mikunis, right?  My 98 has Kehin carbs. 8)