Pamco runs on starter only

[Levett47]

Hi Pete,

Long time reader, first time user. I have a 1979 xs650 special with a pamco ignition + e advancer.

I have a very strange problem where the engine will fire and run beautifully but cut out immediately on release of the starter button.

To this day I have;

- Cleaned and rebuilt carbs twice and installed new jets.
- Rebuilt petcocks.
- Replaced spark plugs with brand new ones.
- Replaced battery with new dry cell.
- Isolated and bypassed starter switch.
- Removed, cleaned and tested charging system (rotor, stator, brushes and Bakelite block)
- Inspected and tested all charging system wires for damage and replaced heat shielding.
- Checked and tested all plug connections (complete new wiring system with motogadget m-unit control unit)
- Tested coil for damage (terminals, plugs and ground)
- Checked spark on both sides. (One at a time always grounding both while checking)
- Checked all grounding points.
- Bypass wire from batt + to coil to check for switch damage.
- Bypass ground wire from e advancer to batt -.
- Checked and replaced all connections twice from coil back to the sensor.
- Checked and replaced all connections from coil back to ign switch.
- Isolated all lights and horn to leave only engine electrics connected.
- Switched plug wires on engine.
- Switched terminal wires on coil.

Nothing has worked and still have the same problem. The engine runs amazing on the starter but cuts without any splutter as soon as I let go of the button. + to coil doesn't cut out though.

I have narrowed it down to the e advancer unit and noticed that there is an auto kill function on that chip to stop the coil from getting ignition until the engine has started.

Could the chip be failing to sense that the engine has started??

 

[pamcopete]

Levett47,

I'm only on my second cup of coffee so I'm not totally focused here, but my first shot at this is your statement "- Checked and replaced all connections twice from coil back to the sensor." Do you mean from coil back to E-Advancer? Or, from coil back to sensor through the E-Advancer?

The auto kill switch works by waiting for both magnets to pass the sensor in the correct order, which is apparently happening. It doesn't check any further once the engine starts and these signals are occurring repeatedly.

I would suggest that you temporarily wire both the "hot" side of the coil and the E-Advancer red wire to a separate battery sitting on the floor, not part of the bikes .electrical system. Don't leave it connected this way for very long after the engine starts if it then quits.

 

[XSLeo]

"Checked and tested all plug connections (complete new wiring system with motogadget m-unit control unit)" I don't know what the motogadget m-unit is, but this could be part of the problem.
If it is what I think it is, you hook the switches to it and things like the ignition, starter lights and such. Then it has relays inside to activate the external parts. If so I think you have it wired wrong.
When you turn the key on, battery voltage gets sent to the ignition. When you push the starter button it should only activate the starter.
It sounds like you have miss wired it some how so the ignition only gets power when the starter button is pushed.
I would suggest you look over the wiring to confirm that you have things wired right.
I'll google the Motogadget m-unit to see what it is.
Leo

 

[XSLeo]

It appears to be what I thought it was. A unit that you hook everything to. It has circuit breakers and relay inside to control everything.
From looking at it I might check for a good ground on the unit. It grounds through the body. I might run an extra ground wire from one of the mount bolts to battery negative.
It is a fancy unit but I don't really see any advantage over just fuses and the stock switches. It does have an alarm unit that might slow down a thief, but I don't feel it's worth that kind of money.
Leo

 

[Levett47]

Thanks Pete.

I replaced each connector between the coil and sensor including the ones joining the sensor to the e advancer (new connector, solder, heat shrink on each wire and another heat shrink over them all).

I'll definitely try your suggestion in the morning. Does that mean I have to have the earth(black wire) from the pamco connected to - of the floor batt as we'll?

 

[pamcopete]

Levett47,

Use a jumper from the negative terminal of the battery on the floor to the frame of the motorcycle and leave the ground connections for the PAMCO just where they are. You can use the negative terminal jumper as a switch. Jumper the red wire from the coil side of the E-Advancer and the coil to the positive terminal of the battery on the floor. Do not have any connection to the wiring of the bike except for the grounds already there. This test will eliminate the bikes wiring and prove / disprove that the PAMCO is working properly.

I think that XSLeo has the answer. There is something in the wiring of that m-unit device that is not working properly or you have simply wired it incorrectly. Using the battery on the floor test will eliminate it completely.

 

[Levett47]

Thanks xsleo,

I have completely taken the m unit completely out and run the ign wire directly to the coil as well as tried a wire directly from the batt + to the coil. Unfortunately neither made any difference.

The unit replaces all relays except for the starter solenoid. Single wires in from switches and single wires out to components. This halves the wiring and is the main reason I got it. But I can't see it being a problem when it's sitting on the bench next to my bike. I have totally removed all lighting electrics to narrow down the problem. I only have the simplified wiring loom from tc bros at the moment.

 

[Levett47]

Thanks Pete,

I'll let you know how it goes tomorrow.

I appreciate your help xsleo and Pete.

 

[XSLeo]

You need to run power to both the coil and Pamco.
Leo

 

[pamcopete]

Levett47,

For the test to be conclusive, you must run the PAMCO and the coil directly from a separate battery, sitting on the floor and not connected to or associated with any wiring in the bike. This test is to either eliminate the PAMCO as a source of the problem or to show that the PAMCO is part of the problem and not some other unknown problem in the wiring of the bike.

 

[pamcopete]

We shouldn't overlook the possibility that the problem is mechanical and not electrical. If the starter motor is permanently engaged and the safety relay has somehow been disabled, then when the starter button is released the drag from the starter motor could stop the engine.

 

[larksnostril]

Hello Pete,
I have your ignition system for about two years and really like it..made such a difference along with a PMA...thanks!

Here's a question about wiring harness replacement on my '81 xs650 SH.
I love long road trips and want to stay stock (well, almost) and the many little electrical glitches got to me so I ordered a new '81 harness from Mikes.
'81 xs650SH is how the title reads.
But the manufacture date stamp on the frame is July 1980.

I know a guy who is a wizard at sorting out complicated electrical problems, has rebuilt many bikes of various makes for many years and is totally compulsive about getting things right. I took my bike to him cuz wiring stuff is not for me.
He got into it and found the new '81 harness did not match the one on the bike (it had never been replaced but had some repairs over the years). So, he got all the wiring diagrams he could locate and found the closest match for the exisitng wiring was the '80 xs750, next closest was the '80 xs650 and they were VERY similar.
Based on the existing wiring plus the manufacture date stamp he concluded that mine is really a 1980 model with the trim details of an '81 and recommended I buy only '80 replacement parts not '81 in the future.
Does that sound like good advice?
Has anyone else run into this particularly regarding sorting out wiring problems?
Charlie

 

[pamcopete]

larks...,

What is your serial number?

 

[xjwmx]

+1 the larks.
Nobody else cares about it as seriously as you will need to.

The '80 is the '81 electrically except for maybe the rear brake light. You're going to have nothing but difficulty until you dig into it your own personal self. If it isn't really a mechanical problem, then the power to your ignition is coming through the starter button. Put the new harness in. Also, many if not all vehicles have been manufactured in the the preceding year. My '81 has an '80 manufacture date I'm pretty sure. But like I said, '80 and '81 are the same electrically. Probably a difference in the rear brake light is all.

 

[XSLeo]

The manufacture dates run from August to July. As in build dates from August 80 to July 81 are 81 models. Your build date of July 80 makes it an 81.
Like most manufacturers they start making their product months before the model year. That way they can get them in dealer showrooms before the year starts. If they waited till January of the model year it would be April or May before any get to the dealers.
The 80 standard is different than the Special. The 80-81 specials are the same.
The 80 standard had a light checker, the Specials didn't.
Mike's harness's often have issues, some of the plugs have the right color wires in the wrong slots. When you plug in an electrical device or switch, check the wire colors. If they match across the plugs then your fine. If they don't match then you need to rearrange the wires in the harness side of the plug.
On the starter drag stopping the engine, I don't think that will happen. With out a safety relay, when the engine starts, wouldn't the splines that pull the gears into engagement with the crank, push the gears out of engagement as the engine rpms go faster than the starter rpms?
This may damage the gear set but not stop the engine.
I've had car starters that the bendix jams and just spins the starter. The engine didn't seem to be effected much if any, but the noise was terrible.
Leo

 

[5twins]

If the bike is an '80 model, it would have BS34 carbs with brass floats. '81 and later BS34s used plastic floats.

 

[larksnostril]

larks...,

What is your serial number?

Wow, that was fast..thanks!
serial # is 4M4003780

 

[pamcopete]

larksnostril,

Could I ask you to start a new thread for your question? We were trying to help Levitt47 with his issue when you asked your question and I think that nobody noticed that you were not the originator of this thread. Things get a little confused when there are two issues in the same thread. Thanks.

 

[Levett47]

Gentlemen, sorry for the late reply. I needed to charge the spare battery and got held up at work. I hooked the floor battery (fully charged) but it didn't make any difference.

I'm starting to think Pete is right here. This could be a mechanical/carb issue. The engine is hardly firing and I'm getting a lot of backfire through the inlets now. And everything is very sooty. I have between 140 and 150 compression so I don't think there is a ring or valve stem leak.

I'll clean the carbs again and see how we go.

Also, I have been running the bike with the tank off so I can test electrical connections around the coil. There is plenty of fuel in the bowls and the vacuum hoses have been plugged. But will this affect anything if there is not a constant fuel flow?

 

[Levett47]

Just a quick update - I adjusted the timing (pamco sensor plate) forward slightly to advance a little and success. Well, minor success. The bike is back to running very good on the starter only.

I have BS38 carbs with brass floats and vm22 210 pilot jets. Is this right?? The original jets were stock size but I put pod filters and a new exhaust with no muffler. These new parts would lean the mixture so I put 30 pilots and 137.5 mains(both one up from stock). I had a feeling that the previous owner changed the carbs or jets and got mixed up with the correct pilots but it all looks good to me. Some advice here would be good..

Engine number is 447-910638