When I turn the ignition key over, after a longer while (i.e., not immediately) the 20A fuse blows. Usually about 5-10 seconds. This has not happened while the bike is running.
The bike is as-is from 1974, any preventative maintenance or other common flaws that may cause this?
Gt550: fuse blows when engine off
Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan
-
- On the street
- Posts: 46
- Joined: Mon Jun 24, 2013 5:05 pm
- Country: USA
- Suzuki 2-Strokes: GT550, RD350, Lambretta TV175, GP125
- Location: San Francisco, CA
- Alan H
- Moto GP
- Posts: 3172
- Joined: Thu Feb 16, 2012 11:50 am
- Country: England
- Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
- Location: The Republic of South Yorkshire
Re: Gt550: fuse blows when engine off
Which position is the key in when the fuse blows?
Off, On, or park?
Take the fuse out and use a multimeter to narrow down where the drain is then sort out the earth or short circuit fault. There shouldn't be anything that would draw that sort of current.
It's either a wire trapped between something and the frame or a part that is failing 'short circuit'. Without some testing, I can't be any more certain. What model is it and do you have (and understand) a wiring diagram?
This needs sorting quickly as if there is a 20 amp fuse blowing, then there is a lot of heat building up somewhere which can easily lead to a fire.
Off, On, or park?
Take the fuse out and use a multimeter to narrow down where the drain is then sort out the earth or short circuit fault. There shouldn't be anything that would draw that sort of current.
It's either a wire trapped between something and the frame or a part that is failing 'short circuit'. Without some testing, I can't be any more certain. What model is it and do you have (and understand) a wiring diagram?
This needs sorting quickly as if there is a 20 amp fuse blowing, then there is a lot of heat building up somewhere which can easily lead to a fire.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
- jabcb
- Moto GP
- Posts: 4241
- Joined: Mon Dec 13, 2010 4:32 pm
- Country: USA
- Suzuki 2-Strokes: 69 T350 thru 75 GT750
- Location: southwestern Pennsylvania
Re: Gt550: fuse blows when engine off
With this much current you may be able to locate the problem by looking for burn marks.
So check all of the wiring connectors you can find. Including under the gas tank & in the headlight shell.
A short can develop from abrasion of wiring insulation.
Check to see if there is any problem where the wires flex from steering the bike.
………………..
As Alan suggested you may be able to use a multimeter to find the problem.
The wiring diagram will be very useful for this task. (See the wiring diagrams topic.)
First disconnect the battery.
Check resistance at the wiring harness connectors for the battery.
For 20 amps at 12 volts you should get a reading of less than 1 ohm.
If you have less than 1 ohm you are in luck.
Then make changes & look for a big increase in resistance.
Operate the switches (lights on/off, kill switches, …).
Strategicly unplug wiring connectors. Do this one at a time so you don't get confused about what connects to what.
Let us know how this goes.
So check all of the wiring connectors you can find. Including under the gas tank & in the headlight shell.
A short can develop from abrasion of wiring insulation.
Check to see if there is any problem where the wires flex from steering the bike.
………………..
As Alan suggested you may be able to use a multimeter to find the problem.
The wiring diagram will be very useful for this task. (See the wiring diagrams topic.)
First disconnect the battery.
Check resistance at the wiring harness connectors for the battery.
For 20 amps at 12 volts you should get a reading of less than 1 ohm.
If you have less than 1 ohm you are in luck.
Then make changes & look for a big increase in resistance.
Operate the switches (lights on/off, kill switches, …).
Strategicly unplug wiring connectors. Do this one at a time so you don't get confused about what connects to what.
Let us know how this goes.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more
Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
- Alan H
- Moto GP
- Posts: 3172
- Joined: Thu Feb 16, 2012 11:50 am
- Country: England
- Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
- Location: The Republic of South Yorkshire
Re: Gt550: fuse blows when engine off
It also could be something like a diode (or diodes) in the rectifier going/gone down and back feeding through the genny.
Last edited by Alan H on Fri Feb 07, 2014 10:31 am, edited 1 time in total.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
- Suzsmokeyallan
- Moto GP
- Posts: 4326
- Joined: Fri Oct 24, 2008 9:11 am
- Location: Mostly Barbados, sometimes Florida and western Canada
- Contact:
Re: Gt550: fuse blows when engine off
Since the circuit blows only after running look at the socket connections such as the regulator, the rectifier, the under tank main harness connection etc.
You should also move the electrical panel and look behind there where the harness wires come close to the inner rear fender. Its a short to ground so its going to be either of the following, the red battery power wires, an orange wire(or wires), the points harness wires and or possibly the yellow phase wires to the alternator.
Dont discount the black/white earth harness wires getting shorted or pinched onto the red battery power wires either.
You should also move the electrical panel and look behind there where the harness wires come close to the inner rear fender. Its a short to ground so its going to be either of the following, the red battery power wires, an orange wire(or wires), the points harness wires and or possibly the yellow phase wires to the alternator.
Dont discount the black/white earth harness wires getting shorted or pinched onto the red battery power wires either.
Two strokes, its just that simple.
69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
-
- On the street
- Posts: 46
- Joined: Mon Jun 24, 2013 5:05 pm
- Country: USA
- Suzuki 2-Strokes: GT550, RD350, Lambretta TV175, GP125
- Location: San Francisco, CA
Re: Gt550: fuse blows when engine off
Thank you guys for pointing me in the right direction. The rubber buffer under the rear end of the fuel tank was gone when i got the bike (since installed) and the tank may have been rubbing excessively on the loom there. Getting into the GT tonight to also swap the crank seals, so a major project evening!
- Alan H
- Moto GP
- Posts: 3172
- Joined: Thu Feb 16, 2012 11:50 am
- Country: England
- Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
- Location: The Republic of South Yorkshire
Re: Gt550: fuse blows when engine off
I think it'll take more than an evening to change crank seals.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
-
- To the on ramp
- Posts: 254
- Joined: Tue Apr 30, 2013 9:28 am
- Country: Lebanon
- Suzuki 2-Strokes: gsx 750R, GPZ 750, GT380
- Location: Lebanon
Re: Gt550: fuse blows when engine off
when i did the crank seals, my wife actually left me. Two suitcases to her mum's. I;m not kidding you.
mj in beirut
mj in beirut
- Alan H
- Moto GP
- Posts: 3172
- Joined: Thu Feb 16, 2012 11:50 am
- Country: England
- Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
- Location: The Republic of South Yorkshire
Re: Gt550: fuse blows when engine off
I wish I'd known that changing crank seals would make the wife leave.
It would have saved me thousands many years ago!
Did she come back when you finished?
It would have saved me thousands many years ago!
Did she come back when you finished?
Think of how stupid the average person is, then realise that half of them are more stupid than that.
-
- To the on ramp
- Posts: 254
- Joined: Tue Apr 30, 2013 9:28 am
- Country: Lebanon
- Suzuki 2-Strokes: gsx 750R, GPZ 750, GT380
- Location: Lebanon
Re: Gt550: fuse blows when engine off
She did actually. But that's not because i had removed the engine from the kitchen table but more cos --- well, i can't say
Can you help me find the cause of my blowing fuse? there' a short somewhere and i dont know where to start.
thanks
Can you help me find the cause of my blowing fuse? there' a short somewhere and i dont know where to start.
thanks