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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: Starquest on February 05, 2020, 06:48:38 PM



Title: Loud backfire, engine quits.
Post by: Starquest on February 05, 2020, 06:48:38 PM
Hello, everybody. After some months of maintenance and recovering from my leg, I run the bike last weekend. Nice weather here in Fl, in the 50s. I had encountered a few problems. The speedometer bounced a little bit above 65mph. I did put a new cable and greased up good. The tachometer started bouncing above 5000 rpm as well as the fuel gauge. Under this speed everything is rock solid. On the way back I stopped at the restroom . I felt a little miss for 1 sec. Next backfire and a miss. Five seconds later another backfire and engine quit running. Took the seat off to check for loose connections, nothing wrong I could seen. Push the star button, fired up and went home. The only thing I did electricaly was put another earth cable from battery to a bolt in the subframe behind the resistors. Carbs are rebuilt, new plugs, checked coils, cleaned coil ground and main ground and some connectors including the kill switch. Thanks to everybody here. I did a lot of reading and I learned a lot. Thanks Robert RPM. The bike runs very good with the rebuilt carbs.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on February 09, 2020, 05:36:36 PM
Update: I took the bike this morning for a ride. I rode it for ten min on the highway at 4000 rpm. All the gauges were fine. I took it past 5000 rpm and the tach, fuel gauge started bouncing. Then a miss. The bike started to cutting off. I managed to take it home at lower speeds. Took the tank off, checked spark plugs, wires, coils 3.6 ohms both. The Haynes manual says 2.7 ohms. My fault. I routed the fuel line above the other two and after riding a little bit and high speeds ,pinched the line. I will try next weekend.


Title: Re: Loud backfire, engine quits.
Post by: balky1 on February 10, 2020, 09:36:50 AM
Before I reached the end of your post I wanted to say to you to check the fuel line routing. Sounds like fuel starvation problem.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on February 11, 2020, 06:21:16 PM
Ok. Thanks. I’m busy this week. I will check Saturday. I’m going to take the fairing off and check all connections at the gauge cluster and run the line under the other two. I can’t believe I made that mistake. Last year I run it under the fuel lines and I didn’t have any problems.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on February 23, 2020, 11:27:56 AM
I went for a ride this morning. I routed the fuel lines correctly, clean the ground coils,lube the speedometer cable,check the coil pick up resistance (162 ohms, orange to black and grey to black) year 1986. I have done the fuel cap mod last year, safety wire the petcock. When I did put the line today,the fitting moved a little bit. Need to order a new one. So I took it to the highway for a short ride.I went to 80 mph. The speedometer was not bouncing,the tach was good and the fuel gauge was not bouncing. The bike run awesome for 5 mins until I went off the highway. Started cutting off and 5 mins later died. I started with not problems and went home. I checked again the pick up coil and went to 205 ohms. It's normal?


Title: Re: Loud backfire, engine quits.
Post by: Pat Conlon on February 23, 2020, 12:16:17 PM
Pick up coils: 149 to 182 is the proper ohm range when the coils are heated up to 68*F
If you took your ohm reading right after your ride, your coils should be toasty warm...

205 ohms is definitely out of spec.  You have 2 pick up coils on your ‘86.
Are both coils reading 205 ohms or just one?
If one coil reads within spec, and the other coil reads 205, then you have a bad pick up coil.

If both coils read 205, then, I would be suspicious....the chances of both coils going bad, at the same time, are slim.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on February 23, 2020, 03:21:22 PM
Before I took a ride today, both coils read 162 ohms. After the ride both coils read 205 ohms. The bike run very good for the first 5 min, then started cutting off even at low speeds.


Title: Re: Loud backfire, engine quits.
Post by: Pat Conlon on February 23, 2020, 03:55:54 PM
Hmmmmmmm...We know as the temperature increases, so does the coil resistance, but by how much?

 Those coils are much hotter than 68*F (ohm test temp.spec.) after your ride, so when the pick up coils are toasty hot, is a resistance of 205 ohms acceptable?

I *suspect* your coils are ok...because both coils have the same reading when hot.

Let’s ask the group....

Something is interrupting your ignition, hence the backfire.
Use a jumper wire to bypass your side stand switch (close the circuit) go for a ride, see if the problem goes away.
Clean your stop/run switch on your handlebar.....you might have a dodgy switch interrupting power to the ignition box.
Perhaps your keyed ignition lock is acting up? Hot wire it....go for a ride, see what happens.

Do not do these all at once. Do this step by step, ruling out each component as they pass the test.

Intermittent electrical gremlins are a bitch.



Title: Re: Loud backfire, engine quits.
Post by: aviationfred on February 23, 2020, 04:43:05 PM
I had a similar fueling issue with my 95 awhile back. I would ride a mile or so and then it would act as if it was running out of fuel. The problem ended up being the Main Control Relay and the fuel pump power contact in the relay. I know your 86 does not have a fuel pump, but the issue could still be your main control relay. Unfortunately Yamaha no longer has any new ones. I did a quick ebay search and there is a NOS one from Germany.

Fred


Title: Re: Loud backfire, engine quits.
Post by: Starquest on February 23, 2020, 05:48:00 PM
Thanks for the input guys. I took another reading 20 mins ago at the connector for the pick up coils. 75 degrees, bike is cool. 168,170 ohms. That relay control is located at the left side on the front fairing? I did disconnect and clean some connector over there. Replaced ignition switch connector, was melted and alternator connector. Now you mention the kill switch. I did notice something today. Bike in neutral,sidekick up. Hit starter button,nothing. Hit it again and started. I broke a little tab on the red connector on the kill switch few months ago before I started to ride the bike this year. I don’t see anything out of place but I’ll try bypass the side stand switch.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 01, 2020, 04:38:14 PM
Update: I was busy this week. Yesterday I took the tank off after I tried to run the bike early. The bike was sputtering,cutting and quit running. So, I found out that the fuel line was pinched at the curve section on top of carb 3. The line I put it 3 months ago was too soft.I replaced with a 3/8 fuel injection hose. The ones that came in 2-3 foot in hard plastic case. The end of the line is curved so I did put it on the t connection and under the 2 lines. I rebuilt the peacock just in case even it was no leaching. Took a 100 mile trip today. Bike was perfect. No even a hiss. Pat, Fred: I tried the sidekick bypass and the control unit that I bought but make no difference. Thanks for the suggestions. I think I’m going to buy the unipods so I can have more room for the lines.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 22, 2020, 02:38:48 PM
I rode the bike last weekend. It ran good for 20 minutes. After filling the tank,I took a ride and the bike cut it off. Wait for 1 min and the bike started and run for the rest of the trip. I was hearing a noise from the tank. I was surprised because I took the little 2 rubber grommets last year from the gas cap. I took it appart and I found out I did put it backwards.The next day I rode it for 2 hours. No problem. Today something weird happened. I was ridding at a constant 5000 rpm and the needle started bouncing 500 rpm down every 5 or 6 seconds,sometimes up. May be a coil or ignition box. I rev the engine pass 7000 rpm and it no make power. Too much fuel?. The bike has 4 to 1 exhaust, unifilter on ope stock airbox, 5 degree advance. 117.5 mains,40 pilots, needle on middle groove.


Title: Re: Loud backfire, engine quits.
Post by: FJ_Hooligan on March 22, 2020, 07:49:29 PM
Check the main ignition connector and the coil connectors under the the front of the fuel tank.  Clean any corrosion and apply dielectric grease


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 23, 2020, 08:47:10 AM
I replaced the connector and pins last year on the main switch. I cleaned the coil connectors too.Where did you get the rpm signal from?


Title: Re: Loud backfire, engine quits.
Post by: Carson City Paul on March 23, 2020, 10:00:33 AM
Take note... dielectric grease is an insulator and should never be applied to metal connectors. 


Title: Re: Loud backfire, engine quits.
Post by: Carson City Paul on March 23, 2020, 10:12:17 AM
After further investigating I have found... 846 Carbon Conductive Grease would be the proper grease on metal connectors after they have been cleaned.


Title: Re: Loud backfire, engine quits.
Post by: T Legg on March 23, 2020, 10:46:31 AM
Would conductive grease cause shorting between terminals on a multipin connectors ?


Title: Re: Loud backfire, engine quits.
Post by: Carson City Paul on March 23, 2020, 11:16:12 AM
Good question, I'm not sure... but I would imagine if you over greased that might be a problem.
I would use the 846 sparingly on the metal components and dielectric grease in the areas water and moisture can penetrate.


Title: Re: Loud backfire, engine quits.
Post by: copper on March 23, 2020, 12:41:21 PM
A good read www.w8ji.com/dielectric_grease_vs_conductive_grease.htm (http://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm)

Conductive grease is at the end


Title: Re: Loud backfire, engine quits.
Post by: Carson City Paul on March 23, 2020, 02:08:55 PM
I don't deny dielectric grease works and has for years. Companies that make these products continually look for ways to improve on their products.
If this were a gimmick and a way to charge more money for a product that did the same as a less expensive product, I might buy what that fellow had to say, but it doesn't cost more and I actually think the manufacturers put the time and effort into producing an improved product that best suits the application. Otherwise it would have been cheaper for them in the long run to just keep selling the same old product.


Title: Re: Loud backfire, engine quits.
Post by: fj1289 on March 23, 2020, 11:35:26 PM
Would conductive grease cause shorting between terminals on a multipin connectors ?

Yes it can!  That’s because it is ”conductive” !

I really like the product Ox-Guard when making battery post connections, ground connections, crimping connectors, etc.   But I was warned to never use it on multi-pin connectors.  I’ve never had a problem on a multi-pin connector because I heed the advice not too!  


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 24, 2020, 03:13:32 PM
The main ignition switch and alternator connectors were melted. I replaced both last year,along with the terminals.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 24, 2020, 03:16:05 PM
More.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 24, 2020, 03:26:54 PM
 :Facepalm:


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 25, 2020, 05:42:54 PM
May be this was the reason for the backfire along with the pinching of the lines. I broke the white tab when cleaning the stop switch last year and I glued it with epoxy. You can see at the picture up left and the pieces of epoxy. I think what happened was that the black piece lifted up and not making full contact or intermittent contact. I switched today with a good one. Contacts were pristine clean. Let’s see Saturday. May be my tach was acting weird because this.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on March 28, 2020, 01:50:19 PM
Ok. I went for a ride this morning. Everything was fine. No jumping on the tach. The speedometer where ok until later on was bouncing a little bit. I did changed the stop switch and starter switch yesterday. Also I did put the pick up coil plate to original position. I think I did advanced too much (slotted plate). I took it to 8500 rpm first time, no problem. Second time and the clutch slipped. Overall I was happy. Time to get parts from RPM. Second gear started to slip. That’s another story. Little by little, one thing at the time. Thanks to everybody. Time to get parts from RPM.


Title: Re: Loud backfire, engine quits.
Post by: Starquest on April 23, 2020, 12:53:49 PM
Sorry.I was busy.After I found a fuel line pinched at the curve section on top of carb 3, I cut a 3/8 hydraulic line that I had at work ad conected to the fuel hoses with safety wire.I ran the bike next day. No problem.The next day I went to start the bike and it was running in 2 cylinders.I touched the pipes,1 and 4 cold.Took the tank off and checked the connector.Connector was a little loose.So I bent the connector terminals and that was it.End of my problems with fuel starvation,cutting off,backfire.I also changed the start kill switch.