Looking for help with MCI MC9/8v71 Starting issues in Gainesville, FL area

TheHeavenlyChillbillies · October 24, 2021, 12:39:56 PM

Hi there.

I am just checking if there is anyone in the Gainesville/Jacksonville area that can help me trouble shoot some starting issues with my bus. Up until now the bus has had very few issues. I drove the bus for about an hour in March '21. I replaced the batteries about 6 months ago. I returned to the bus, that sat for 6 months, and when I went to start the bus the batteries had run down. The starter/solenoid did some clicking but did not turn over. I charged up the batteries for a day...and when I went to start the bus I got absolutely nothing except for a single relay click in the engine compartment. It's in neutral, the brake switch is up, I have tried starting from the back and front.

Upon reading it seems like it's probably a switch somewhere in the starting circuit.
Generally I don't mind doing my own tinkering...but I am in a time sensitive situation and need to get the bus running asap.

Just checking to see if there is anyone in the area that is familiar with the bus that can give me a hand. Ideally I'd like to get her started so I can take her to a mechanic and give her a once over.

Thanks in advance for any leads.

someguy · October 24, 2021, 12:45:55 PM

Short out the starting solenoid with a wrench or a pliers handle and see if it turns over. It should actually start doing that.

If that doesn't work, it is time to get out the multi meter and start tracing voltages along the path from the key to the alternator and also from the battery to the solenoid power terminal. One very useful test is to connect one multimeter terminal to the battery and the other to the solenoid power terminal and measure the voltage drop when the key is turned. Should be 1-2V. I'm guessing you'll see 20V+, ie you have a poor connection somewhere.

What is the battery voltage after being charged ? What was it before ?

If I had to guess, I'd say there is an issue with the battery disconnect switch. The fact that the solenoid clicks when you turn the key means that the path from the key to the solenoid is probably OK.

Good luck. Let us know what you find.

TheHeavenlyChillbillies · October 24, 2021, 01:12:23 PM

I'm not sure that the click is coming from the solenoid...it seems to be coming from the top of the engine somewhere.

Where is the starter located? Can I access it from one of the side compartments? Or do I need to get under the bus.

I'm looking through the manuals but don't see an actual location of the starter.

I'm familiar with automotive electronics, and where a lot of things on this bus are...I just haven't had to do anything with start circuit yet.

Ed Hackenbruch · October 24, 2021, 01:25:53 PM

I would start by cleaning all of your cable ends and battery posts.....they probably need it anyway.

TheHeavenlyChillbillies · October 24, 2021, 01:37:34 PM

Ok.
I see the starter now

Right behind my fuel filters. I'm going to start checking some voltages there and try jumping the solenoid after I do a little cleaning. Pretty dirty back there.

The I cleaned all of the posts battery terminal ends when I put the new batteries in. Everything is cranked down tight. Getting 25.30 volts from batteries. Same on the other side of battery switch when it's engaged.

I'm going to check for voltage at the starter and try jumping the solenoid terminals and report back.

I looked for the fuel pressure switch on my filters...but I can't find any electrical wires coming from the assembly. I believe it is after market because my bus uses screw on filters.

luvrbus · October 24, 2021, 01:46:22 PM

The starter relay is the back junction box that is what you hear clicking ,remove the cover it will have a diagram telling which is the starter relay pushing the starter button it should have voltage on both sides if just one side the relay is bad , don't worry about the little wire it is working or the relay would not be clicking

TheHeavenlyChillbillies · October 24, 2021, 02:17:32 PM

Some progress.

So i jumped the two large terminals on the back of the solenoid and the starter motor spun up. The engine didn't crank...I'm assuming because the solenoid wasn't engaged. Should I be jumping the two small terminals?

TheHeavenlyChillbillies · October 24, 2021, 02:34:46 PM

Update:
So I found the Rear Junction Box. It is not that relay that is clicking when the ignition is activated. It's something else coming from the main engine compartment. The starter does have 24v coming to the one side of it. Now to figure out why it isn't engaging.

luvrbus · October 24, 2021, 03:27:36 PM

The 2 small terminals on the starter solenoid one is a ground the other is Bat, if you jump from the main cable to it then the starter will engage watch not to short to ground that is the one on the engine side they are marked if you can read it Bat and ground, now the clicking is from Skinner valve on the back fire wall for the stop and start if it comes from around the top of the engine.The 1st thing I would check is make sure the shifter is in neutral

chessie4905 · October 24, 2021, 03:39:31 PM

careful. If ignition is on, engine can start in 1/2 revolution. Quite startling when under there. Also, while trying to start from drivers seat, move shift lever back and forth a little bit. May neutral switch is dirty.

TheHeavenlyChillbillies · October 24, 2021, 07:28:59 PM

Cool. I'll try jumping the solenoid in the morning. Could I jump the starter relay as well? It's a little easier to get to...unless it's the reason for failure.

The first thing I checked was if it was in neutral...I have fallen for that a few times. I also shifted it back and forth while the key was turned. Checked brake as well. It does seem like that is the issue...some open switch breaking the circuit.

luvrbus · October 25, 2021, 06:05:02 AM

Quote from: TheHeavenlyChillbillies on October 24, 2021, 07:28:59 PM
Cool. I'll try jumping the solenoid in the morning. Could I jump the starter relay as well? It's a little easier to get to...unless it's the reason for failure.

The first thing I checked was if it was in neutral...I have fallen for that a few times. I also shifted it back and forth while the key was turned. Checked brake as well. It does seem like that is the issue...some open switch breaking the circuit.

A bad neutral switch or a wire broke on it can cause a open circuit ,you need to buy a remote starter button for 15 bucks and use it standing up on the outside of the bus for your own safety 24v under a bus can light things up

TheHeavenlyChillbillies · October 25, 2021, 03:36:34 PM

Progress!

So I used a set of jumper cables to successfully start the bus from the starter relay in the rear panel. Now that I know the bus can be started and driven I can catch a breath

I'll trouble shoot the neutral switch in the near future.

Thank you all for your help.

TheHollands! · November 21, 2021, 06:53:26 PM

Hi Heavenly, Any update on what the cause was on your starting issue? I had a real similar problem a few years back and was starting it by laying under the starter and jumping the terminals for a while till I could resolve the problem. That was some scary stuff. I ended up finding that there was a bad connection in the wire from the rear junction box to the neutral safety switch (some kind of connector piece mid wire closer to the actual switch. Fixing this resolved the issue that sounds real similar to what your experiencing.
Craig

Busted Knuckle · November 23, 2021, 12:39:13 PM

Just one suggestion before you dig too deep. Is the step light and chimes switch on or off?

Old hounds were wired so that the starter would not activate unless the step light and chimes switch was on to keep anyone w/o this knowledge from starting them!
(you'd be surprised how many experinced drivers have gotte bit by this little item!)

BK