1991 FXSTS ( EVO )

Sudenly started to backfire

Topics on all other models that fit in no other section
Post Reply
neilw
Member
Posts: 352
Joined: Sat Dec 20, 2008 3:24 am
Bikes: 1995 Roadking(still brand new)
1991 HD springer
1959 pan (I'm reassembling)
1991 BMW 75RT.
Location: Calgary
Has thanked: 91 times
Been thanked: 18 times

1991 FXSTS ( EVO )

#1

Post by neilw »

I have been riding my 1991 Springer quite a bit this summer, yesterday it started to backfire when gearing down . I had never had this before .It still has the stock carb.
It still runs good other than that. In my search for a cure I took the bowl off the stock carb ,and blew air through the slow jet, and high speed one . With the air cleaner off I started the bike . When I quickly twist the throttle it back fires through the carb, fire shot out ..To me ,this sounds like timing ,I've been told it maybe running lean, but I had not done anything to make it suddenly run lean, I sprayed started fluid by the intake as the engine was running , it made no difference ..Not being a mechanic, I am thinking it may be timing ,and caused by an electrical malfunction somewhere. maybe the VOES ? One thing electrical that happened a few days ago , the signal lite canceler stopped working , Would this be connected to the ECM and possibly be related ? Any advise will be appreciated .
Mongrel505558
Senior Member
Posts: 1418
Joined: Thu Mar 26, 2020 5:46 pm
Bikes: Rigid Panhead bobber, 68 Shovelhead, 2000 Road King Police bike, 2000 Dyna Wide Glide
Location: Rhode Island
Has thanked: 991 times
Been thanked: 701 times

Re: 1991 FXSTS ( EVO )

#2

Post by Mongrel505558 »

I don't know if this has anything to do with it, but my 2000 Dyna stopped running because of a turn signal circuit board gone bad. In my case, the TS board also contains a bank sensor that shuts the motor down if it detects that the bike is leaning past a certain angle for a certain amount of time (like laying on its side from an accident or tip-over). One of my rear turn signal wires was pinched in the fender and it cooked the board. My ECM wouldn't allow the bike to start because it thought the bike was laying on its side. So at least by 2000 the turn signal board was tied into the ECM. Can't give you any more than that. I know a lot more about pans and shovels than I do about anything more recent.
neilw
Member
Posts: 352
Joined: Sat Dec 20, 2008 3:24 am
Bikes: 1995 Roadking(still brand new)
1991 HD springer
1959 pan (I'm reassembling)
1991 BMW 75RT.
Location: Calgary
Has thanked: 91 times
Been thanked: 18 times

Re: 1991 FXSTS ( EVO )

#3

Post by neilw »

Thanks , I'll check the wiring ..
As for the back fire , my other bike ,a BMW died on the highway, I got it home and drained the full tank of gas out , then removed the fuel pump looking for clues , I put it back together and the bike started. Being the bike died half a mile from where I gassed up, could it have been water in the fuel I wondered . I saved the gas and used some in my lawn mower ,after 15 minutes it quit after sputtering, I changed the fuel filter ,and it ran good until next time to mow, I used the same gas from my bike. Back to the BMW ,now at a shop ,after it staring again I took it fior a ride close to home because I had no idea why it quit . I had put a bit of the old gas in,and went to the gas station and filled up. 25 kilometers it died after sputtering.. I gave up on looking for answers . THEN my Harley that was running great started back firing and I had added some of that old gas from the bmw, I'm just thinking the whole thing may be water in the gas.. I don;'t know if water would cause the bike to back fire . I'm going to get a fuel filter and run the old bmw gas through it ,then see if my mower works , if so I drain the Harley tanks . What a nightmare ,everything dying at once , and all had the old gas in some amount in the tanks ..
RooDog
Senior Member
Posts: 5327
Joined: Tue Oct 31, 2017 1:00 pm
Bikes: 1950 Panhead, Resto-Mod
1968 90", 5 Speed Shovelhead,
1984 Home Built Custom Evo 100" Bagger
Location: Knoxville, Tennessee
Has thanked: 2801 times
Been thanked: 2158 times

Re: 1991 FXSTS ( EVO )

#4

Post by RooDog »

1) A filter will nor remove water.
2) Drain your gas into a clear glass jug, I know, it's not a safe thing to do, but how else are you gonna see if, after resting over night, if water has settled to the bottom of that container.
3) Drain all your gas out, and put in fresh gas from a different dealer. Can you get 100% gas somewhere, eh?
neilw
Member
Posts: 352
Joined: Sat Dec 20, 2008 3:24 am
Bikes: 1995 Roadking(still brand new)
1991 HD springer
1959 pan (I'm reassembling)
1991 BMW 75RT.
Location: Calgary
Has thanked: 91 times
Been thanked: 18 times

Re: 1991 FXSTS ( EVO )

#5

Post by neilw »

WATER IN THE GAS !!
Yep all my problems are from the gas I got when I fueled up my beemer . As I mentioned ,using the gas I drained from my beemer ,my lawn mower quit, my Harley srtarted back firing for the first time .
Long story short... I bought 2 fuel filters ,one clear so I could see the fuel. and drained the bad gas into another container . I put some of the cleaned gas in my lawn mower and it works great ,next I drained the Harley tanks and float bowl and added the cleaned gas . it runs great now . As for the beemer at the shop, I dont like working on stuff with EFI, and computers ,and ABS . So I'll let them drain the tank and what ever else they do .. I had my lawn tractor loaded on my trailer and tied down ,hooked to my suv and ready to take it to the shop when I decided to drain the tank and put clean gas in.. Good thing I did !
Mongrel505558
Senior Member
Posts: 1418
Joined: Thu Mar 26, 2020 5:46 pm
Bikes: Rigid Panhead bobber, 68 Shovelhead, 2000 Road King Police bike, 2000 Dyna Wide Glide
Location: Rhode Island
Has thanked: 991 times
Been thanked: 701 times

Re: 1991 FXSTS ( EVO )

#6

Post by Mongrel505558 »

Glad you got it sorted out. Coincidently, when I had that issue with my Dyna from the fried turn signal board it didn't quit all at once. It ran crappy and I was able to limp it home. First thing I did was empty the tank thinking I had bad fuel. I had just filled it at a station I had never used before.
Post Reply

Return to “Other models”