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Discussion Starter · #1 ·
I recently purchased a 99 suzuki marauder vz800. Little over 18k miles. Cranks up fine, idles fine, getting good spark, fuel pump working fine, runs good and smooth. After riding for about 7-10 minutes it starts running a little rough, but accelerating good, backfire ever so often until it dies. Figured it was running hot. Checked both radiator sensors, works fine, overhear light never comes on, flushed and changed coolant, inspected water pump, no issues. Usually it's around the time the radiator can comes on its when I start having the issue. Again, overheat light never comes on. After I let the bike cool down a bit it cranks up fine, idles fine, runs fine, then back to square one. I've covered fuel delivery and coolant components. Could it be something electrical? If so what should I look for it test?
 

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Sure could be something electrical failing when it gets hot.
BUT.....you should first crack open the gas tank lid when this happens, because it could be a plugged tank vent causing a vacuum in the tank to stop the fuel flow.
It also could be the fuel pump failing when it heats up a bit.

Outside chance that your battery is weak and/or the charging system isn't up to snuff.......and the radiator fan is dragging down the voltage.

What about the exhaust ?
If it is not stock OR it has leaks, it could be blowing exhaust heat on things not meant for that.
 

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Discussion Starter · #3 ·
It's aftermarket exhaust pipes. I was also having a backfire noise for a while during normal running but I took out the pair valve and capped everything off and that stopped that issue.

It has a new agm battery that seems to hold a charge good.

The fuel pump was shot and I put a brand new one on that's working good.

I haven't tried opening the gas tank. I'm fairly new to bikes so I will ask, where is the tank vent? I did notice underneath the tank near where the fuel lines connect to the tank the is a metal tube about 1"long sticking out the bottom. It's kinda rusty and no house is connected to it.

My long time friend went to MMI and has been riding bikes since I've known him and he's helping me out. Just having trouble with this issue. It is puzzling to say the least.
 

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Discussion Starter · #5 ·
Late to update but I found the problem. One of the female spade connectors on the front ignition coil was loose and not getting a good solid connection so when the bike vibrates while running, it was causing issues with the ignition coil. I swapped the ignition coils and still had the same front cylinder issue so that let me know it was not the ignition coil. Started messing around with the spark plug cable and bumped into one of the wires on the back of the coil and it came right off. New female connectors all around and now she runs just fine.
 
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