Help! Cold Start--No Idle, Stalling

All of a sudden, my 2004 ST1300 doesn't idle and stalls out before the engine temp reaches 3 bars. It starts up fine and idles for about a minute, then chokes out quickly.

When I start to ride, have to keep the throttle twisted to keep the revs above 1000 or I stall out at stop signs and lights. Once the bike warms up, it seems like it idles fine and doesn't stall.

I live in So Cal so it's never really "cold" when I start it, maybe in the low 60s.

I don't know if there's any relationship here, but I started noticing this issue after adjusting my counter balancers.

Any ideas?

Mandel.

How old is your battery? My '06 did the same thing, only it would give me a FI light too on occasion. They replaced my battery and it has been fine ever since.

This is exactly the same behavior my bike presented, occasionally throwing a FI trouble code "2". Code 2 implicates a bad MAP sensor or a vacuum leak. In my case a replacement MAP sensor and a session tightening all of the throttle body boots did the trick. I also adjusted the cold opening position of the starter jets via the adjustment nut on the SE thermal valve (make sure the starter jets been checked for sync first). The combination of these actions solved my problems.

Others have reported a cracked or plugged vacuum "T" leading to the MAP sensor. Though I haven't seen it reported a bad/stuck SE Thermal valve that does not properly pull the starter jets open when cold could also cause this problem.

There's not likely to be any ill effects from adjusting your CBs.

Mine's done that a few times. I'd yank the air box and make sure the wax engine and its linkages are all in good health.

When do you start to ride? Do you just take off or wait for the temperature gauge to reach one bar?

--Mark

It's not the battery. Just replaced mine a few weeks ago and it's fully charged.

I typically wait for two bars before riding, sometimes more, sometimes less. But now with the idle problem I can;t let the bike sit while it warms up or it will stall. So I just start it up and start riding gently while it gets up to temperature.

Hey Bertrand, where do I find the MAP sensor and vacuum T?

Mandel.

Do you wait for the F1 light to go off before pushing the starter button? My thought is that if not, there may not be sufficient fuel pressure at start up to maintain an idle without wicking the throttle.

FWIW (for what it's worth), Here's what I think.

When the engine is cold, the butterfly valves are closed in the throttle bodies. In order for the engine to start and run, each of the four throttle bodies have a port (opening) that must be in an open position as a result of the solidified wax in the Wax Thermal Switch. This is the normal "cold" position of the ports. As the engine warms up, warm coolant circulates through the Wax Thermal Switch and the wax begins to melt. The WTS slowly closes the ports. At the same time, as a result of the engine warming, the butterfly valves are opening to maintain intake air supply for the engine.

It seems as though your ports aren't opening. Because you are maintaining 1000 rpms with the throttle, you're opening the butterfly valves, and as the engine warms, the butterfly valves will stay open on their own.

If you shut of the engine after it is warm, does it start right up again and idle normally? If it does, then the WTS, or the associate linkage is probably at fault. It could be that the linkage is binding or something is interfering with their movement.

Good luck,

Dale

I guess I can live without the bike idling while it's warming up and just pump the throttle instead.

But is there any danger in riding the bike with this problem? Once it's warmed up it seems to run fine, and it starts right up and idles OK once the bike has warmed up.

Mandel

Mandel said:

It's not the battery. Just replaced mine a few weeks ago and it's fully charged.

I typically wait for two bars before riding, sometimes more, sometimes less. But now with the idle problem I can;t let the bike sit while it warms up or it will stall. So I just start it up and start riding gently while it gets up to temperature.

Hey Bertrand, where do I find the MAP sensor and vacuum T?

Mandel.

Click to expand...

They are both (as well as the SE thermal valve) under the the air cleaner housing.



In this shot (from the right side, front of the bike to the right) you can see the MAP sensor at the lower left corner. It's the black thing with the gray harness plug connected to it. The vacuum T is just off the bottom middle of the picture, you can see two vacuum lines from cylinders 1 and 3 leading to it.

The SE thermal valve can be seen between the throttle bodies for cylinders 1 & 3 below the brass colored fuel rail. Note the plunger extending up toward the center of the shot where it engages with the starter valve linkage. When cold, the wax in the SE valve contracts and pulls the linkage downward against the springs that would ordinarily hold them closed. As the engine warms, the wax melts and expands, extending the plunger upward and releasing the starter valves, allowing the springs to close them.

Adjusting the SE thermal valve for the correct cold idle is a bit tedious. You have to have a bone cold engine and do the adjustment pretty quickly after starting the engine before it starts to release the starter jets, you've only got a minute or so. In order to double check your setting you have to leave the bike to grow completely cold again. I dialed mine in over about 2 - 3 day period.

make sure to check all the other possibilities first before messing the SE valve or you'll end up having to adjust it back downward if something else like a vacuum leak is found. Don't ask me how I know this!

Thanks a lot for your thorough explanation Jeff. This looks like it is beyond my modest capabilities, however.

I'm due for a major service in about 1200 mi. and may just let the STealer deal with it.

Mandel.

Mandel said:

Thanks a lot for your thorough explanation Jeff. This looks like it is beyond my modest capabilities, however.

I'm due for a major service in about 1200 mi. and may just let the STealer deal with it.

Mandel.

Click to expand...

What service are you coming up on?

52,000 mi. It doesn't sound like a service interval, but the dealer said that's my next one.

Mandel.

Mandel said:

52,000 mi. It doesn't sound like a service interval, but the dealer said that's my next one.

Mandel.

Click to expand...

Do you know what they plan on doing?

Sounds like the same symptoms my ST had, it grew more problematic over time until I couldn't get home without keeping the throttle near wide open.....

https://www.st-owners.com/forums/showthread.php?t=62676&highlight=vacum+line+clogged

I think I might found the solution to this problem.
The following were quote from STOC website.

Had the same problem when i got my 06 STX about 2 years ago. Replace autochoke and problem came back. But was then resolved when i sent it back again. The mechanic (Meng Tong) told me that there are 8 small holes in the air filter chamber, that is, if you take out the air filter you can see the 8 holes in the housing. These 8 holes should be clean. After he did that and tune fast idle at 1.5k ok for about 9 months. He said that the cleaning action would usually resolved the autochoke problem for about 9 months to 1.5 year.

When washing my air filter about several months ago, told the mechanic (another one) to do the same, so far been perfect except for only one occasion. Mileage since first cleaning the 8 holes was about 20k so far. Autochoke problem first hit when bike mileage was about 57k.

Hope this helps.

nothing works!!

I even replaced the coolant and flushed the radiator and the problem still around!!!

Having the same trouble with mine at the moment. Started the bike from cold on my way to work and noticed that the bike didn't run the auto choke from cold start and then wouldn't idle it would just drop below 1,000 rpm and then stall, it did seem to take a while though to start idling fine while i was riding to work. Was fine on my way home in the evening but tonight it has done it again and wouldn't idle till it was warm.

Many Thanks

Lee

Did anyone find the problem? My 2007 is doing it. And it has been going on for a month or so.

Replaced the air filter, spark plugs, fuel filter & strainer, t-connection is ok too. I don't know where to go from here. Help.

I'm having the same problem too, posted this on the st1100/1300 facebook page this morning and the Honda pan euro UK facebook page....

Morning everyone, I have a question, I started my ST1300 this morning to warm up and it kept revving as if I was twisting the throttle. And then stalled, so i started it again and the same happened. Any ideas what it could be? In the end I had to get on and keep the on revving the engine, especially when stationary, i.e at traffic lights.
On Friday I put some super unleaded in the tank, could this be the problem?
Thanks
Mike.

I had an issue with mine, But mine on start up would stall ever so often until the 3 bars was showing on the temp gauge. wouldn't do it all the time but would mean when it did you had to hold the throttle open while waiting at light, otherwise it would stall. There would be no Fi light come on neither.

I did a bit of looking on here and brought a new Five way joint, which as we took it off and inspected it one of the holes was blocked. Clean up and unblocked the old one and put the new one on and Job done. So far so good bike is running good again.

Many Thanks

Lee