ST1100

[ian]

Not about FJRs but no help on ST board. My son rides my old 95 ST1100. He met me in AR a month or so ago. About 30 miles down the Interstate after leaving Omaha, the bike died. After he pulled over, it fired up and ran fine for 25-30 miles and it died again. Did this all the way to Joplin, MO. Using my limited knowledge, I checked the bike over and didn't find any obvious problem. I suspected poor gas tank venting causing increased vacuum but got no whoosh when tank opened after riding and the vent hose seemed clear.

The next day, we went to a MC shop south of Joplin. Mechanic also thought the tank venting was OK, there was good fuel pressure out of fuel pump but exhaust analysis was very lean. My son is hideous at maintenance and the carbs were gummed up and out of whack so they were rebuilt, new plugs, etc.

Riding in the twisties at 50-80 mph the next three days, there were no problems what-so-ever. Thought it was fixed. Even riding north on MO19 from AR to I 40 at fairly high speed, he had no problems. As soon as we hit four lane MO65 going north toward I70, problem recurred. Thinking it was caused by riding at a constant speed, he varied between 60 and 80 mph (fun to follow him!). This seemed to work until north of Kansas City (on I29) when it started dying again. After that he kept the speed about 60 and that worked until we got home.

He's going to take it to a shop at home but I wonder if anyone has any ideas. TIA Ian, Iowa

 

[03HiYoSilver]

ian,

Well, if it is not a fuel related problem, I am wondering if the Coil(s) could be heating up and dieing? Or even a Fuel pump could be ready to give it up...especially when running on lower levels of fuel.

Good Luck on your fix.

 

[shuswaper]

ian...when was the last time the fuel filter was replaced? For some reason this item is not mentioned in the owners nor service manual !

 

[Charlie Hoss]

A Canadian friend, I won't mention his name, but his initials are GYPSY, had a similar problem around midnight in southern Maine, had his bike towed 80 miles to a nearby Yammy dealer and I picked him up at 2 AM and brought him home.

Long story short, it was a simple loose battery cable. It was tight enough to work MOST of the time but quit working a couple of times. That really sucks in the middle of the night.

If the ST shuts down suddenly, I would suspect electrical, loose connection, etc. Ign switch? Check all elec connections for corrosion and put some dielectric grease in the connectors before reconnecting.

 

[ahchiu]

I had a 00 ST1100, never had the problem you mention, but someone @ WESTOC 08 had the same problem check your fuel filter, wire connection to fuel pump(top of tank), and fuel pump relay. do you hear the fuel pump go for a few seconds when you turn the key on? have you tried to run some Seafoam through your tank also check your battery connection. how old is your battery?

 

[madmike2]

IIRC, carbureted STs don't have a fuel pump.

Fuel filter or loose electrical connector. I once bought a used car that acted that way and it was a plugged filter.

 

[FJRay]

IIRC, carbureted STs don't have a fuel pump.
Fuel filter or loose electrical connector. I once bought a used car that acted that way and it was a plugged filter.

Tank is lower than the carbs. Has to have a fuel pump . Good thought on a filter issue.

 

[charismaticmegafauna]

IIRC, carbureted STs don't have a fuel pump.

Lots of carburetted bikes have fuel pumps -- especially the latest ones (before the on-set of universal fuel injection).

Both the fuel pump and it's electrical relay can be suspect in any diagnosis... :huh:

 

[Maura]

IIRC, carbureted STs don't have a fuel pump.
Fuel filter or loose electrical connector. I once bought a used car that acted that way and it was a plugged filter.

The ST1100 has a fuel pump inside the tank. On bikes that have been sitting for a long time it is notorious for gumming up and not working. I had mine replaced with a non-functioning used one. Oh joy. Eventually sprung for an new OEM. More f*cking joy. At least it worked. I am by no means suggesting that your problem IS the fuel pump, just throwing in my experience for what it is worth.

Fuel filter and batter cable are easy and cheap to address, would investigate those two first.

 

[BikerGeek99]

I had a mid-80's-ish Nighthawk that would do the same damn thing - it's always a joy to have the engine die when you're mid-turn in traffic. :angry2:

The problem turned out to be the ECU (or ignition controller thingy or something like that). Swapped the flaky one out for a new one and was good to go.

 

[Fred W]

Is the "cut-out" very sudden and complete when it happens?

If so, it might be a flaky connection with the sidestand / neutral safety circuit.

I'm not fluent in ST1100's, but most reltively modern bikes have a side stand switch of some sort that will kill the ignition if the side stand is down when the bike is in gear.

Usually any sort of a fueling problem on a carby bike would cause the engine to stumble some before dying out, like running out of gas. If you are convinced that it is a fueling issue, the tank venting can be eliminated by running with the fill port cracked open (as a test). Of course it would be best to try when the problem is actually happening Also might be worth checking out any fuel petcock devices. Many carburetted bikes have vacuum operated petcocks that like to screw up. These can cause fuel starvation problems.

Just a few random thoughts.

 

[sredder]

I currently have a 99 ST (ABS) and have had several other ST's in the past. What was the temperature during the ride? ST 1100's have a known carb ice issue. When ridden close to freezing (45F or below and dependent on humidity), you can get carb icing like in a private airplane. I now block off the air snorkel with a piece of foam in the front edge of the fairing when the temps are under 45F If you have this issue, you will first notice that the engine appears to be missing slightly and then gets progressively worse until it quits. it feels like the bike is starving for fuel, but it is not. If you let the bike sit for a few minutes, the ice melts and all will run fine for a few more miles until the ice builds up again. One usually notices this more the higher the humidity gets.

Hope that helps!

Sredder

99 ST 1100

02 FZ-1

05 FJR A

08 FJR A

 

[Aasland]

Check (by bypassing) the vacuum-operated fuel valve.

With the plastic cover off (the one over the air filter housing), on the right side, there's a valve. It has three hoses - fuel in, fuel out, and vacuum. This is the petcock valve. Inside there's a rubber diaphram which is known to crack and leak .. resulting in restricted fuel flow. Many ST owners have had problems with this, and many have bypassed it completely.

I was taking care of a friend's ST1100 which wouldn't run at length high speeds or maintain speed on long uphill climbs at 45mph. First I bypassed that valve, and all was OK. THen I bought a rebuild kit from K&L and now it works great.