Purchased a 03 ST1300 with a toasted alternator, I have replaced the alternator and the thermostat. Rode for approximately 150 miles with no issues. The last ride was at 30-50 mph and after 1/2 hour the engine started to cut in and out at lower speed but fine at higher speed. then it progressively got worse in the higher speeds. Has anyone else had this issue? Knowing how hot the engine area gets my first guess is that a wires insulation has melted off and is contacting ground, next guess is the on/off switch, the last item would be the kickstand switch/wiring circuit. Any other ideas would be appreciated.
ST1300 Engine bucking at low speed, cutting in and out
- Thread starter Wrencher
- Start date
diferg
Dan & Ingrid
do you have a cruise control? If yes check for vacuum leaks. if not possible fuel pump problem.
No cruise. It’s a hard very abrupt miss not a softer miss like a fuel starve. Also with hard acceleration there is no miss at all, goes like a jackrabbit.
Sounds like your fuel pump is on its way out.
- Joined
- Nov 20, 2005
- Messages
- 949
- Location
- Cedar City, Utah
- Bike
- 12/04/AZ05 ST 1300s
- 2026 Miles
- 000616
You mean like this:
Bad fuel pump!
I replaced with one off eBay. just make sure the hoses that you put in it are rated for being in the fuel.
Bad fuel pump!
I replaced with one off eBay. just make sure the hoses that you put in it are rated for being in the fuel.
sirbike
Site Supporter
You are having the same performance, symptoms and thoughts as I had.
I didn’t want to throw parts at a problem but throwing a fuel pump at it, a bike with 96,000 miles, would at least be preventive on a model know to lose fuel pumps. The fuel filter was changed at 60,000 miles.
Anyway a new fuel pump solved the problem.
By the way, the abruptness of the cutouts had me thinking ignition but if that was the case it would have popped unburned gas when the ignition would cut in.
I didn’t want to throw parts at a problem but throwing a fuel pump at it, a bike with 96,000 miles, would at least be preventive on a model know to lose fuel pumps. The fuel filter was changed at 60,000 miles.
Anyway a new fuel pump solved the problem.
By the way, the abruptness of the cutouts had me thinking ignition but if that was the case it would have popped unburned gas when the ignition would cut in.
As @SupraSabre said, make sure you use the proper fuel hose. Many of the hoses provided with fuel pumps purchased from Amazon are not rated for direct immersion in gasoline and will fall apart if you use them, leaving you stranded. Your best bet is to throw away the hoses that come with your new pump (unless you buy the pump from a reputable source) and buy hoses from an auto parts store.
diferg
Dan & Ingrid
PS: 
Welcome to the forum from Southeast Georgia USA.
Welcome to the forum from Southeast Georgia USA.Thanks for all the info! I took it out yesterday naked and it ran great. I am not sure if the fault was that the pump got warm and started misbehaving or something else. I do have a fuel pump coming and will change it out as a preventative measure. Thanks for the note regarding the fuel hoses, I have seen them disintegrate if emersed in fuel.
Diferg: thanks for the welcome
Diferg: thanks for the welcome
If there is a problem with fuelling doesn't that show a FI light with attendant code? The symptoms described by the OP sound very similar to those I experienced with my 185,000 mile A9 1300 a few years ago and I was assured by those who knew more than me that the problem was electrical because any fuelling problem would result in an FI light. New spark plugs, HT leads, coils and a crank sensor were tried to no avail, the bike becoming more unrideable every day. Because it was a work bike I could not spend ages trying anything else so it was sold to a breaker. After six years on other bikes I am now back on an ST1300.
The FI like is Fault Indicator - not a Fuel Injection indicator of some sort.
Andrew Shadow
Site Supporter
The ST1300 is to old to be that sophisticated. Modern vehicle ECM's can monitor any combination of fuel flow, fuel pressure, fuel temperature, fuel alcohol content, etc.. The ST1300 ECM is based on cutting edge technology from the late eighties. It has no direct knowledge of what the fuel system is doing.