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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: RockyMountainRider on December 27, 2011, 07:12:52 PM

Title: Damn bike won't start
Post by: RockyMountainRider on December 27, 2011, 07:12:52 PM: So, the bike sat for years, but the previous owner had it running a month or so ago when I bought it. Now I can't get it started again.
Battery is charged.
Air filter is clean
Fuel filter is clean
Drained old gas and put in a gallon of fresh gas.
Fuel pump whirrs for a second when key turned to on position.
Brand new plugs and I tested and I am getting a spark.
Bypassed the side stand switch.
Removed fuel line from fuel rail and there is fuel there (not sure if it's pressurized or not of course).

So, ideas? Anything funky about these bikes that I'm missing? If the motronic had an issue, would I be getting a spark in the first place?
Title: Re: Damn bike won't start
Post by: frankenduck on December 27, 2011, 07:16:02 PM: Kill switch?
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 27, 2011, 07:18:39 PM: kill switch was in middle position
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 27, 2011, 07:31:02 PM: I guess I should be specifically asking if the motronic or anything else can stop the bike from running if it's getting spark and gas?
Title: Re: Damn bike won't start
Post by: frankenduck on December 27, 2011, 07:59:56 PM: Pull the plugs. See if they're wet. (flooded) Not usually as much of an issue as it can be on K75s but I suppose it's possible. You shouldn't need much, if any, "choke" (it's actually a throttle advance so the engine if FI'd) or throttle when starting it.

If you're getting spark and the fuel pump whirs when you turn the key the it's probably not a Motronic issue but can't hurt to reseat the Motronic connector and double check the fuses.

Probably not your issue but checking the TPS positioning can't hurt: Adjusting the TPS (Throttle Position Sensor) on a 4V K bike (http://www.motobrick.com/index.php/topic,1521.0.html)
Title: injectors clogged?
Post by: kennybobby on December 27, 2011, 09:28:31 PM: If the pump is working then the fuel rail would likely be pressurized. If the Motronic is getting all the necessary sensor signals then it would be firing the ignition and the injection pulses, so there would be voltage pulses at the injectors if you have a volt meter or scope. But if the injectors have set up and gotten clogged and gummed up with old alkyhol fuel, then they would prevent the bike from running. i think you could loosen the bolts on the fuel rail to pull the entire rack of injectors, then see if fuel is actually coming out the injectors when you crank it.
Title: Re: Damn bike won't start
Post by: frankenduck on December 27, 2011, 10:19:06 PM: It's a lot easier to pull the spark plugs then to mess with the fuel rail. If the cylinders are getting fuel and the bike isn't starting then the plugs will be wet.

He also stated that it was running a month ago. I doubt the injectors would clog up in that short period of time.
Title: Says he has spark...
Post by: kennybobby on December 28, 2011, 12:08:22 AM: Quote from: RockyMountainRider on December 27, 2011, 07:12:52 PM
So, the bike sat for years, but the previous owner had it running a month or so ago when I bought it. Now I can't get it started again.

Brand new plugs and I tested and I am getting a spark.

If the motronic had an issue, would I be getting a spark in the first place?
By all means it is much easier to pull the plugs than the rail, and if they are wet with fuel, then they are fouled and will need to be replaced.

And if the plugs are wet, then fuel is getting past the injectors--maybe they are stuck open and flooding the cylinders with too much fuel and it is too rich to start. You will have to pull the rail to troubleshoot if the injectors are stuck open.

It's probably not likely that the previous owner might have spiked the intake with some fuel in the airbox just to get it to run and get it sold, but it wouldn't be the first time that sort of thing has been done...

No. if the Motronic had an issue it wouldn't be firing the ignition (so that tells me that the hall sensors (crank trigger) are working).

But if the engine temp or intake air temp or engine speed sensors are not working then Motronics will not pulse the fuel injectors. If you measure a voltage pulse at the injectors connector then the motronic is trying to work, which implies all the required sensors are working to allow it to start. Other sensor failures can cause a limp-home mode when running, but it will still start.

So if it is firing spark and is pulsing voltage at the injector connectors and still not starting, then it may not actually be getting fuel thru the injectors. Either the rail has no pressure (fuel pump) or the injectors are open circuit or the injectors are clogged.

Measure fuel rail pressure, if okay then you can measure the electrical resistance of the injectors to determine if they are open circuit. If they measure within spec then you have to pull the rail to troubleshoot possible clogging of the injectors.

Or the motor is worn out and has low compression (leaky rings) and will not start even with fuel and spark present... (do a compression check)
Title: Re: Damn bike won't start
Post by: BrickFlyer on December 28, 2011, 03:39:19 PM: Here's a very helpful diagnostic tool that will teach you alot about the bike's system. The author did a super job of explaining how all the elements of the motronic system work together and it has a nice color schematic if you have to dig deeper.

[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm (http://[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm)
Title: Re: Damn bike won't start
Post by: frankenduck on December 28, 2011, 04:24:13 PM: Quote from: BrickFlyer on December 28, 2011, 03:39:19 PM
Here's a very helpful diagnostic tool that will teach you alot about the bike's system. The author did a super job of explaining how all the elements of the motronic system work together and it has a nice color schematic if you have to dig deeper.

[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm (http://[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm)

That's for a 2V K100 with an analog L-Jetronic. The bike we're dealing with here is a 4V K1100 with a digital Motronic contoller. There's some similarities but there's lots of differences too.
Title: Re: Damn bike won't start
Post by: sup on December 28, 2011, 04:26:40 PM: Excuse my poor english, please :embarass:. My suggestion is to check the multiple connector on the motronic unit. Sometimes it seems to be fixed well but it is not. Then the effect is as above described. Ciao :2thumbup:.
Title: Re: Damn bike won't start
Post by: motodude on December 28, 2011, 05:41:56 PM: Quote from: frankenduck on December 28, 2011, 04:24:13 PM
Quote from: BrickFlyer on December 28, 2011, 03:39:19 PM
Here's a very helpful diagnostic tool that will teach you alot about the bike's system. The author did a super job of explaining how all the elements of the motronic system work together and it has a nice color schematic if you have to dig deeper.

[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm (http://[http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm)

That's for a 2V K100 with an analog L-Jetronic. The bike we're dealing with here is a 4V K1100 with a digital Motronic contoller. There's some similarities but there's lots of differences too.
Quote from: sup on December 28, 2011, 04:26:40 PM
Excuse my poor english, please :embarass:. My suggestion is to check the multiple connector on the motronic unit. Sometimes it seems to be fixed well but it is not. Then the effect is as above described. Ciao :2thumbup:.

I recently had a similar problem w/ a 2V K100, the reason I didn't chime in earlier is because you have a 4V 1100 and I know jack about Motronic (slightly less than jack about L-Jetronic). The bike-wont-start site indicated above is very useful but it does reference a 2V K100 as Frankenduck indicates. Probably worth a read though. I "fixed" my problem by cleaning the connector to the L-Jetronic box and ensuring it was well seated. It was not the first time I attempted to ensure it was "well seated" but it was the first time, I'd sprayed it w/ contact cleaner. I also cleaned and re-seated several connectors under the tank but I've convinced myself that it was the L-Jetronic connector that made the difference. I could be wrong. In my case, I had good spark and good fuel pressure but no start.

If you choose to use contact cleaner, don't get in a rush. I sprayed mine (the connector not the unit) and let it sit overnight to dry before plugging it back in. Checking/cleaning other electrical connections certainly won't hurt either. Especially if the bike has been sitting.

Tom
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 31, 2011, 01:55:28 PM: well, finally got around to my continued effort to get the bike started. Pulled the plugs: they were dry. Checked and actually replaced all of the fuses (put ones in that have LED lights that appear when blown). Disconnected and reseated the motronic. Swapped the motronic relay with the horn relay. Still nothing. Pulled the TPS and measured the voltage across pins 1 and 4 with the key in the on position and did not get any voltage whatsoever. Seems like I am getting closer. So, no voltage to the TPS means? Bad motronic? Should I try some dielectric grease on the motronic connections? Swap out the motronic?
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 02:13:26 PM: If the plugs are dry then it sounds as though it's not getting fuel for some reason.

Did you mess with the wiring at all? There's quite a few grounds and if you didn't get them all connected then that might be an issue.

How did you bypass the sidestand switch?

If you pull the injectors, at least in my experience, then you'll have a hard time getting the old hardened O-rings to seal when you put things back together.

Since it sat for several years, there is most likely some varnish built up in the injectors. Even if I were able to get the bike running I'd still have the fuel injectors serviced and new O-rings. There's a guy in Idaho who does them for $16/each with a quick Priority Mail turnaround so I'd do that regardless on a bike that has lots of miles or has sat for an extended period.

More info here: Getting Fuel Injectors Reconditioned (http://www.motobrick.com/index.php?topic=1064.0)
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 31, 2011, 02:29:45 PM: let me be a little more clear. the plugs were dry, but smelled of gas (normal in my opinion). i bypassed the sidestand switch by connecting the two wires to one another. i do plan on getting the injectors cleaned, but want to get the bike running. as i said earlier, it has run on a few occasions in the last month or so, so i do not believe they are bad enough to stop the bike from running. I have a new tank and will swap that in next to see if the fuel pump is the problem. It whirs but that does not necessarily mean its creating pressure (as I understand). I have checked all of the wiring on the bike in case I disconnected a ground. Any other ideas?
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 04:20:56 PM: If the plugs are dry and it's not firing when it spins then that means that it's not getting gas to the cylinders.

Has it run since you bypassed the side stand switch?

How did you bypass the side stand switch? Similar to the attached picture?
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 31, 2011, 05:01:11 PM: I just temporarily spliced the two wires leading to the sidestand switch and twisted them together. It was not running B4 I did this or after it. The plugs are getting gas - they're brand new NGK Iridium plugs (bike was not running B4 I changed the plugs). Does the TPS have anything to do with not starting, as I am not getting any voltage between pins 1 and 4?
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 05:17:09 PM: Are you testing the TPS with it's wiring harness connector attached?

If it's getting gas but not firing then the plugs wouldn't be dry. If you're pumping gas into a cylinder and it's not combusting then it will make the plug wet. This is simple physics.

Are you sure the spark plug leads are properly connected? You need to push them on pretty hard on these bikes. If there's any wiggle on the spark plug cap at all then it's not all of the way on.
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 05:24:55 PM: Also, did you screw caps onto the NGK plugs?

(http://www.hickieracingservices.com/images/b8es.jpg)
Title: Re: Damn bike won't start
Post by: johnny on December 31, 2011, 06:18:24 PM: (http://i236.photobucket.com/albums/ff192/owrstrich/2011/2011%20Misc%20Ch1t/4b57dc3e.jpg)

j o
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 31, 2011, 06:38:53 PM: caps on the NGK plugs? That's a new one to me. The bike was not starting with the old plugs in either. Where does one get these caps? I guess I clean up the old plugs and put them back in. The wires were on tight - no wiggle. I was testing the TPS at the wiring harness, with the TPS itself completely removed.
Title: Re: Damn bike won't start
Post by: Inge K. on December 31, 2011, 06:58:38 PM: And you got the genuine caps? Which would look like this on the inside:.....

(http://i496.photobucket.com/albums/rr326/IngeKarlsen/Plugghette.jpg)

Inge K.
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 07:03:12 PM: The TPS can't function unless it's plugged in. Put a couple of skinny wires in with the 1 and 4 terminals when you connect the TPS. Monitor the voltage across those.

Most spark plugs come with the screw on caps. For some reason the dumbasses at NGK don't include them with their plugs. It's a generic part though. Either buy four cheap plugs just to get the caps or use the caps from your old plugs. Note that on some Bosch plugs they are removable, on other Bosch plugs they are not....

If you want some cheap plugs that come with caps and work on Ks then get a set of Autolite 4163 plugs.
Title: Re: Damn bike won't start
Post by: Rick G on December 31, 2011, 08:58:10 PM: Have you actually tried to find if you have spark. in doing this make sure that you test only #1 & #2 and do them one at a time. don't leave a plug lead disconnected as you can damage the ignition system. Put a plug in the cap and put the body of the plug on the engine as you crank the engine.
If you have spark at both 1 and 2 then check if the injectors are operating when cranking the engine.
If the injectors are not working remove the rail and the cap from the injectors and apply 12 volts (they should click) to try if it is the injector itself or the motronic unit not operating them.
Check to see if the fuel is circulating by looking in the tank when the pump is running, if there is only a gallon then you will see it very readily.
Title: Re: Damn bike won't start
Post by: RockyMountainRider on December 31, 2011, 09:35:57 PM: I had previously tested for spark and I am getting a spark with the old plugs and the new plugs. weird that I was getting a spark with the NGK plugs with threaded connections. The plug wires are original (as is everything else on the bike: only 21,000 miles). I will test the TPS next. How does one test to see if the injectors are firing?
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 09:56:45 PM: So far you've claimed that you have both fuel and spark but have given us absolutely no idea as to how you've come to either conclusion so it's damned hard to help you.

And why on God's green Earth would you try to run the engine with the TPS removed/disconnected?

You might be better off taking your bike to a mechanic.....
Title: Re: Damn bike won't start
Post by: johnny on December 31, 2011, 10:46:52 PM: this moto is in colorado... could it be the altitude switch...

j o
Title: Re: Damn bike won't start
Post by: frankenduck on December 31, 2011, 11:13:57 PM: Quote from: johnny on December 31, 2011, 10:46:52 PM
this moto is in colorado... could it be the altitude switch...

j o

That only applies to 2V L-Jetronics.

I' m think'n this one is more IQ-related.
Title: Re: Damn bike won't start
Post by: Rick G on December 31, 2011, 11:16:54 PM: With the plugs sparking try both #1 & #2 because they are seperate circuits and if one of them isn't working then the engine possibly won't even sound like it wants to start.
My K1100LT had one plug lead off and it just didnt even come close to starting.
First thing I would try with the injectors is to put the handle of a screwdriver in your ear and the tip on the steel body of the injector and crank the engine, you will probably hear a slight click as the injector activates on every revolution of the engine. If you can get to them try it on all four.
If you can hear the click you know the electrical circuit is working. I would then undo the two bolts and remove the injectors and see if they are releasing fuel when they click. Try to do each injector into a small container and watch the spray of the nozzle, the fuel should come out as a fine mist not a squirt.
If the fuel does not spray well get them serviced.
If that is all ok then test the compression but usually compression doesn't just drop off suddenly.
If you do remove the injectors replace the O rings as they often leak after being disturbed. They may have never been out before.
The plugs will fire without the little screwon caps but you will find the leads don't stay on and the capson the leads will erode because of the sparking and will eventually fail.