86 GL1200 SE-I won't start just backfires


Information and questions on GL1200 Goldwings (1984-1987)
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repairman1101
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Motorcycle: 86 GL1200 Aspencade SE-i

86 GL1200 SE-I won't start just backfires

Postby repairman1101 » Fri Feb 06, 2015 9:14 am



been working on this for a week trying to figure it out. Get fuel gets fire new timing belts all timed correctly. Could it be the ECM?



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virgilmobile
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Re: 86 GL1200 SE-I won't start just backfires

Postby virgilmobile » Sat Feb 07, 2015 12:42 pm

Backfiring...in the exhaust or air box.
In the exhaust...Fuel is being ignited in the headers,so you do have fuel,air and spark.Maybe not in the correct proportion ot time.
Being a fuel injected unit,I'd first verify that the plug wires have not been reversed.Then check the compression...expecting above 130 psi,wide open throttle.
is the fuel fresh or old and funky?

repairman1101
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Joined: Fri Feb 06, 2015 8:59 am
Location: somerville, Texas
Motorcycle: 86 GL1200 Aspencade SE-i

Re: 86 GL1200 SE-I won't start just backfires

Postby repairman1101 » Sat Feb 07, 2015 12:45 pm

Back fires through the exhaust. The bike was running down the road fine the stalled and won't fire back up. Fuel is fresh and compression is 135 on all four cylinders

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virgilmobile
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84 GL 1200 I

Re: 86 GL1200 SE-I won't start just backfires

Postby virgilmobile » Sat Feb 07, 2015 6:07 pm

Ok.lets assume that the spark is fine.The bike just stalled out.
This should be gas related.Can I assume its fuel injected.?
Do you have a manual for it.?
As always,when working with a fuel injected wing,I always point to a electrical problem.
The most important part of the system is the 5 volt reference voltage that is fed to all the sensors.This voltage is generated by the ECM module.
Some have had problems with the throttle position sensor.There is a method to test it too.
I have seen this voltage measure low and the "fix" was simply unplugging and plugging back in the ECM.It seems a poor electrical connection upset the whole system.
There is always fuel pressure to consider also.Measure it.Dont quote me but I think it has about 25psi at rest and 55psi while running/cranking.

repairman1101
Posts: 4
Joined: Fri Feb 06, 2015 8:59 am
Location: somerville, Texas
Motorcycle: 86 GL1200 Aspencade SE-i

Re: 86 GL1200 SE-I won't start just backfires

Postby repairman1101 » Sat Feb 07, 2015 6:14 pm

Yes it is fuel injection I do not have a Manuel. How do I test tps ?

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virgilmobile
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83 GL1100 I
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84 GL 1200 I

Re: 86 GL1200 SE-I won't start just backfires

Postby virgilmobile » Sat Feb 07, 2015 6:40 pm

Ill look for a few test points asap.

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virgilmobile
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Joined: Sun Sep 19, 2010 5:39 pm
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78 GL1000
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82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 86 GL1200 SE-I won't start just backfires

Postby virgilmobile » Sat Feb 07, 2015 6:50 pm

It looks like the throttle sensor has 3 wires.the red/white should be 5 volts.The green/blue is ground.The light green should go from 5 volts to zero volts as the throttle is operated.
The fuel pump has 2 wires.Green is ground.Brown is 12 volts during cranking and running.
The voltage across the two wires(red/white and green/blue) needs to be between 4.75 and 5.25 volts.

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virgilmobile
Posts: 7646
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
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78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 86 GL1200 SE-I won't start just backfires

Postby virgilmobile » Sat Feb 07, 2015 6:58 pm

By the way.Fuel pressure specs....34-38 psi key on,engine stopped..28-34 psi at a idle.

repairman1101
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Joined: Fri Feb 06, 2015 8:59 am
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Re: 86 GL1200 SE-I won't start just backfires

Postby repairman1101 » Sat Feb 07, 2015 7:13 pm

Tested the tps by ohm and it rise and lowers smoothly we it out skip and when I checked voltage I could not find and voltage




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