2007 Mastif Dies when hot

A

agourabob

Member
I am helping a friend with his bike. We live in the Palm Springs area (hot) and when he stops at a light, outside temps above 90, after riding 10-15 minutes the bike stops running, will crank but no firing. If we allow it to sit for 15 minutes, it re starts and runs again for a few miles. We removed a plug wire and no spark.

He took it to a Harley mechanic and that person changed the coil assy, and after 20 minutes, the bike died again.I suggested a service manual to start with, but I see many posts about ECM's and ignition modules and switch (key) assy's.

Before we start sourcing modules I thought we would ask if anyone has experienced this? I fully understand it could be a bad connector pin, but I hope one of you has seen this.

I have no idea if EFI has failed also, maybe trying to simulate the failure in a garage and with heating up the modules one at a time would cause the failure to show up.

Thanks in advance.

Bob
 
standuprick

standuprick

Active Member
I had a bike years ago that when it heated up the coil would work. It could be possible the mechanic installed a defective coil. Just a chance. Also, check the spark plug wires. Trace the wire leading to the coil. I would start there first. Its the cheapest route
 
erldawg

erldawg

Guru
agourabob said:
I am helping a friend with his bike. We live in the Palm Springs area (hot) and when he stops at a light, outside temps above 90, after riding 10-15 minutes the bike stops running, will crank but no firing. If we allow it to sit for 15 minutes, it re starts and runs again for a few miles. We removed a plug wire and no spark.

He took it to a Harley mechanic and that person changed the coil assy, and after 20 minutes, the bike died again.I suggested a service manual to start with, but I see many posts about ECM's and ignition modules and switch (key) assy's.

Before we start sourcing modules I thought we would ask if anyone has experienced this? I fully understand it could be a bad connector pin, but I hope one of you has seen this.

I have no idea if EFI has failed also, maybe trying to simulate the failure in a garage and with heating up the modules one at a time would cause the failure to show up.

Thanks in advance.

Bob
Click to expand...
Hi Bob, Generally when someone posts on the forum they introduce themselves to the members out of respect.

To answer your question- The EFI has a protection circuit that will cut the engine out above certain temperatures. Although the engine should still run. There is also a relay that controls the fuel pump and I know at least one person has had a similar issue and the relay was bad. When the bike quits running turn the ignition off. Then go through the start procedure, turn key on, let the speedo sweep, then hit run switch, at this point you should hear the fuel pump running if you do not then relay is bad.

The EFI module which is separate from the EHC controls all ignition & fuel functions after input from the sensors.

Here's a partial wiring diagram Message - Big Dog Biker Gallery Click on the diagram to enlarge it...
 
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A

agourabob

Member
So sorry for not introducing myself, I have a 2002 Honda Gold Wing and I run the Shadow Hills Riders Club, Del Webb Shadow Hills. Which Don the Big Dog owner is a member. I'm a former electronic technician of 40 years and a pretty good wrench. He has been left out in the cold by non qualified mechanics and there is no BD repair shop that he knows of anywhere in the So Cal area. he found a dealer in Vegas, but it is a real hassle to truck the bike there and not be local enough to watch the progress. I volunteered to help him and the input from all of you experienced owners and techs is invaluable.

About the bike, we hear the pump run when key is on after the quitting, and the tach sweeps. That's why we assumed there was EFI working. I was unaware the bike has any thermal cut off built in.

We need a direction, I would assume ignition module is bad when hot, I thought we would locate the Ignition module and heat it with a blow dryer, or wait for it to fail and see if any voltages went away, either to the coil or to the Ig module. If that does not seem to be the failure, then heat the ECM and see what happens. If the engine has a temp shut down, where might that be sensed?

Many thanks to the fellows who posted the electrical wiring diagrams, most helpful.

Thank you for your input and mentioning about introducing myself, since I don't own the bike I felt awkward.

THANKS
Bob
 
A

agourabob

Member
That was on our list to check, how did you determine it failed? Ohmeter check? Where did you find a replacement?
Thanks
Bob
 
BigDogBro1

BigDogBro1

Made in the USA
2007 Mastifs are not efi, only the Bulldog models.

If it happens near the same time from a cold start then a crank sensor could be heat sensative.

We replaced one for another reason by a cut and splice near the front instead of a full cable tear out.....big job.
 
bearman

bearman

Active Member
ditto on the crank sensor.

there is a red LED on the ignition module that should come on after turning on the key then pressing the run button. it should blink when starting, not dim but completely go off and back on. if it does not blink then crank sensor is the most likely culprit. they seem to go out when hot and work for a limited time when cooled back off then quit completely. Mine seemed to run fine when i could get it started but would die if I let it idle, so if I kept the revs up it would run.
I had to take off my left side cover to see the led on the ignition module.
 
A

agourabob

Member
On a 2007, where are the ignition module, ECM mounted? We will be looking at the bike this week and without the service manual, I would hopw they are accessible.

Bob
 
BigDogBro1

BigDogBro1

Made in the USA
On the Bulldogs, the EHC is located inside the RH battery cover. Mastiff should be similar.

If you take off the seat you should be able to see the EHC and cables.
 
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