2018 Pioneer 700 - issue that doesn’t make sense

[mike04]

So long story… recently out riding and the pioneer shut off while my wife was driving it. Note that it shut off right after going over some significant bumps.

Initially it would start back up but then die as soon as put in gear and throttle pressed.

Now it will not start at all except very intermittently and with no rhyme or reason. As soon as you press the throttle it will die, and will still shut off randomly shortly after starting.

A friend who is a mechanic has tried to help figure it out. It is getting. Fuel to the spark plugs and the spark plugs are sparking. Air intake is clear. Good compression check. He doesn’t think it is a timing issue because it will start and run occasionally and the valves are not tight. Ran a dedicated temporary ground to make sure it wasnt a ground issue. The exhaust is not blocked. Confirmed that the PCM is working correctly by swapping the PCM with the one in my dads. You can hear the fuel pump cycle on and as said the spark plugs are wet when it spins over. Wiring harness appears to be in ok shape but there were a few wires with the coatings chewed by mice apparently. That has been fixed and nothing is shorting now. Checked with a volt meter.

Any other thoughts or suggestions?

Thank you!

 

[mike04]

So long story… recently out riding and the pioneer shut off while my wife was driving it. Note that it shut off right after going over some significant bumps.

Initially it would start back up but then die as soon as put in gear and throttle pressed.

Now it will not start at all except very intermittently and with no rhyme or reason. As soon as you press the throttle it will die, and will still shut off randomly shortly after starting.

A friend who is a mechanic has tried to help figure it out. It is getting. Fuel to the spark plugs and the spark plugs are sparking. Air intake is clear. Good compression check. He doesn’t think it is a timing issue because it will start and run occasionally and the valves are not tight. Ran a dedicated temporary ground to make sure it wasnt a ground issue. The exhaust is not blocked. Confirmed that the PCM is working correctly by swapping the PCM with the one in my dads. You can hear the fuel pump cycle on and as said the spark plugs are wet when it spins over. Wiring harness appears to be in ok shape but there were a few wires with the coatings chewed by mice apparently. That has been fixed and nothing is shorting now. Checked with a volt meter.

Any other thoughts or suggestions?

Thank you!

Oh and the only code it initially gave was an intermittent ground issue. That code was cleared and did not come back after running dedicated ground. It then later threw a TPS code but the TPS wouldn’t cause a complete no start or very intermittent start

 

[HondaTech]

I cant remember if that year has it or not, but look under the front passenger side fender, if there is a ground light there, check it.

That lug is specifically for the regulator/rectifier.

We recent had a 2023 700 with the same issue, idled all day, but would die when applying throttle. Customer hadn't mentioned he had just installed a winch and mounted his ground to that lug. It was finger tight!!

 

[HondaTech]

Oh and the only code it initially gave was an intermittent ground issue. That code was cleared and did not come back after running dedicated ground. It then later threw a TPS code but the TPS wouldn’t cause a complete no start or very intermittent start

TPS can cause no starts if the ecm thinks the throttle is wide open. These machines have a clear flood program that won't let it inject fuel or spark to clear fuel out of the system.

 

[mike04]

TPS can cause no starts if the ecm thinks the throttle is wide open. These machines have a clear flood program that won't let it inject fuel or spark to clear fuel out of the system.

Thank you, will check both of these recommendations and report back.

 

[mike04]

Thank you, will check both of these recommendations and report back.

As an update, replaced TPS. Still no start. Any other ideas on this? Just doesn’t make sense

 

[mike04]

Also checked the lug mentioned above. My friend has basically checked the entire wiring harness at this point. No broken wires.

 

[WagginTail]

Ignition switch? Just a wild guess

 

[HondaTech]

Ignition switch? Just a wild guess

We did have a Pioneer 500 with a bad ignition switch. If you turned it directly to crank it would start and run. If you turned it to run and then crank, it would shut the dash off and not start, but would crank.

We found one of the terminals inside corroded and not making contact. Customer complaint was no shifting and stalling.

 

[WagginTail]

We did have a Pioneer 500 with a bad ignition switch. If you turned it directly to crank it would start and run. If you turned it to run and then crank, it would shut the dash off and not start, but would crank.

We found one of the terminals inside corroded and not making contact. Customer complaint was no shifting and stalling.

I seem to remember @DG Rider replaced one on his

 

[WagginTail]

Also checked the lug mentioned above. My friend has basically checked the entire wiring harness at this point. No broken wires.

Did you check fuses?

 

[DG Rider]

I seem to remember @DG Rider replaced one on his

I did. Twice. But it turned out not to be the issue.

 

[DG Rider]

I cant remember if that year has it or not, but look under the front passenger side fender, if there is a ground light there, check it.

That lug is specifically for the regulator/rectifier.

We recent had a 2023 700 with the same issue, idled all day, but would die when applying throttle. Customer hadn't mentioned he had just installed a winch and mounted his ground to that lug. It was finger tight!!

Is this on the newer 700's? Pretty sure my 2020 doesn't have one there.

 

[HondaTech]

Is this on the newer 700's? Pretty sure my 2020 doesn't have one there.

I've got to look at a wiring diagram to see, but I believe it was 2019 or 2020.

 

[mike04]

Did you check fuses?

Yes checked all fuses. And gone through the whole wiring harness from the pcm wire by wire.

 

[mike04]

The dash seems to work correctly on this one. No dash cutting out etc. it will spin over consistently but just no start. Randomly it will start and run in neutral but then will shut back off. Runs fine at idle while it runs. Still no break through on what the problem is.

 

[BigMac]

Have 2016 that had connected sprayer directly to battery. He should have went thru fuse or accessory plug that has fuse in honda.

Think it had a short that burnt part of stator. Kept getting worse. At first only died when been running awhile and only would start after it sat a while. Later it would not start most of time.

Mechanic in St Joe found it after others failed. He noticed with advice from factory that stator did not charge enough to keep fuel injectors running when warm. Battery is not sufficient to run the engine even though it had charge.

Replaced stator still runs great.

 

[mike04]

Is there anything besides the computer that would cause it to fire out of time? It has good compression, good fuel pressure, engine timing is good, valves are good, and has good spark. We swapped the computer with a known good one and still would not run. And put the computer from it in another one, and that one would run.

 

[osobad]

Is there anything besides the computer that would cause it to fire out of time? It has good compression, good fuel pressure, engine timing is good, valves are good, and has good spark. We swapped the computer with a known good one and still would not run. And put the computer from it in another one, and that one would run.

I would lean toward a connection to ground somewhere. They can reck havoc on voltage issues.

 

[DG Rider]

Is there anything besides the computer that would cause it to fire out of time? It has good compression, good fuel pressure, engine timing is good, valves are good, and has good spark. We swapped the computer with a known good one and still would not run. And put the computer from it in another one, and that one would run.

Have you verified that the injector is firing? As in actually watching the spray pattern?
Water in gas can cause some odd behaviors similar to some of the things you've mentioned.

Why are you asking about firing out of time? Be aware that during the 1st few revolutions, the 700 fires the plug every time the piston hits TDC...or twice as often as it normally would. Looks like this...

I believe the Rincon's (the atv where this engine came from) used to have a thing wherein occasionally, the key for the flywheel would shear off allowing it to shift on the crank. That would cause issues.