honda foreman wont rev up

[trailcutter 13]

looks like i will have to take tank and heat shield off to get to it,it is hard to believe it takes so many wires to make a machine run anymore.

[trailcutter 13]

found it.

[trailcutter 13]

anybody have issues with the diode in the fuse box?

[retro 4,048]

The Diode is an electronics protection component. It prevents flyback voltage that is released from the Starter solenoid when the Starter button is released, from damaging sensitive electronic components such as ECMs and ECUs. Every now and then one fails but not very often. The Diode's function is unrelated to your issue.

[trailcutter 13]

ok thanks,another thing i have found is if i leave the key on for awhile and start it up it will rev up, but if i put the lights on it wont rev up,the opposite of when the battery hasnt had a draw and have to put the lights to get it to rev up

[retro 4,048]

Sounds like it still has china parts on it.

[trailcutter 13]

the thing that gets me is if parts are faulty how they can perform at all depending on voltage.

[jeepwm69 7,619]

11 hours ago, trailcutter said:

the thing that gets me is if parts are faulty how they can perform at all depending on voltage.

They’ll “work” but not like they should.

 

If you hook a 12v battery to a 6V system, the stuff will work for a bit, but you’ll burn up the 6V stuff as it wasn’t designed to work with 12V

 

It is impossible to troubleshoot a Honda with china electrical parts on it.  Been there, done that.  
 

 

 

[trailcutter 13]

the issue was there before with the oem parts.

[trailcutter 13]

so today i took the lights fuse out and have no ignition except to winch,any suggestions?

[jeepwm69 7,619]

So rereading the whole thread, verify that you have now put on a used OEM CDI, a new carburetor, and the original OEM regulator back on it?

 

I work like you do, kinda jumping all over the place, but for the sake of the guys trying to troubleshoot over the internet, need to go one step at a time, verifying what you’re done/swapped out.

 

 

[trailcutter 13]

i still have chinese cdi on machine am still waiting for the used cdi.and yes have put oem regulator back on

[retro 4,048]

If I were you I would unplug that china CDI immediately and remove it. That china junk can start a fire and burn your Foreman down, along with the building that it is parked in.

 

Also, if any of the other parts on your Foreman are aftermarket, you'll need to remove those as well and replace will genuine Honda parts.

 

We cannot help you until all of the aftermarket parts have been replaced with Honda parts. Let us know how it runs when you get it sorted out.

[trailcutter 13]

what does the cdi have to do with no ignition with  no light fuse,my feelings are i had this issue before i changed the cdi that maybe damaged the oem cdi.

[retro 4,048]

10 minutes ago, trailcutter said:

no ignition with  no light fuse

 

Removing the light fuse disconnects battery voltage from the ignition switch. See the wiring diagram.....

[retro 4,048]

While you are replacing china parts with OEM parts you may as well check the Ignition switch for an intermittent function issue. If the ignition switch has been replaced with china you'll have to correct that with OEM too.

[trailcutter 13]

that seems strange why would the system be wired so thar engine would shut down because a lightfuse has blown,and why do i still have power to winch?

[retro 4,048]

20 minutes ago, trailcutter said:

my feelings are i had this issue before i changed the cdi that maybe damaged the oem cdi.

 

Three common reasons why OEM CDIs fail are:

• The Diode in the fuse box fails in an open circuit condition, which allows flyback (high) voltage to discharge into the CDI.
• Water gets into wiring harness connectors causing corrosion of the terminals - open circuit condition.
• An OEM electrical part replaced with a china part.

Speculation is generally a waste of time though, until diagnosis of failed circuits is complete.

 

Just now, trailcutter said:

that seems strange why would the system be wired so thar engine would shut down because a lightfuse has blown,and why do i still have power to winch?

 

Refer to the wiring diagram.... for "why" questions. Short answer: there are two power circuits controlled by the ignition switch, not one.

[trailcutter 13]

i asked about the diode and you said it wasnt related to my issue.

[retro 4,048]

Another common issue I see quite often is hacked up wiring harnesses and add-on accessories that are wired into the harnesses on the wrong power supply circuits, and I often just find wires stripped bare and twisted together and taped up with electrical tape.  I work on a lot of Honda's that are owned by cattle ranchers. Most of them are cobble-job artists who have no business working on their own equipment. So if you are not the original owner of your Foreman, it'd be a good practice to go over your harnesses and fix any connections that are cobbled or connected into the wrong circuit (check your winch wiring or add-ons if ya got any). All add-on wiring connections should be soldered and waterproof sealed up.

 

40 minutes ago, trailcutter said:

i asked about the diode and you said it wasnt related to my issue.

 

Right, an open or shorted diode has nothing to do with how the motor runs, it only functions the moment you release the starter button.

 

You can check the diode after you remove it from the fuse box by setting your multimeter to Continuity mode, or Resistance mode. Then touch each of the two diode terminals with your two multimeter leads and note whether the diode conducts or not. Reverse the two multimeter leads on the diode terminals to note if the diode conducts or not in the opposite polarity.

 

A good diode should conduct current flow in one direction only.

So if your diode conducts in both polarities the diode is shorted (depending on the ATV model a shorted diode may result in a no spark - no start condition).

If it does not conduct in either polarity the diode is open circuit (which allows flyback voltage to discharge into the CDI and/or shift ECM if equipped).

Only if the diode conducts in one direction, but does not conduct in the opposite direction, is the diode a good one.

[retro 4,048]

Your IN/OUT winch switch and contactor relay (if equipped - some old Warn winch installations did not include a contactor, but had a high current capacity rotary switch on the handlebar) should be connected into a switchable, fused circuit such as the accessory circuit, which is provided for add-on purposes. Check your add-ons..... you left a clue that your winch may be wired up incorrectly, directly to battery positive....? While the ignition switch is turned OFF the winch should not operate.

[trailcutter 13]

32 minutes ago, retro said:

Your IN/OUT winch switch and contactor relay (if equipped - some old Warn winch installations did not include a contactor, but had a high current capacity rotary switch on the handlebar) should be connected into a switchable, fused circuit such as the accessory circuit, which is provided for add-on purposes. Check your add-ons..... you left a clue that your winch may be wired up incorrectly, directly to battery positive....? While the ignition switch is turned OFF the winch should not operate.

there is a selenoid that is activated by the ignition

[trailcutter 13]

35 minutes ago, retro said:

Your IN/OUT winch switch and contactor relay (if equipped - some old Warn winch installations did not include a contactor, but had a high current capacity rotary switch on the handlebar) should be connected into a switchable, fused circuit such as the accessory circuit, which is provided for add-on purposes. Check your add-ons..... you left a clue that your winch may be wired up incorrectly, directly to battery positive....? While the ignition switch is turned OFF the winch should not operate.

diode is good

[trailcutter 13]

1 hour ago, retro said:

Another common issue I see quite often is hacked up wiring harnesses and add-on accessories that are wired into the harnesses on the wrong power supply circuits, and I often just find wires stripped bare and twisted together and taped up with electrical tape.  I work on a lot of Honda's that are owned by cattle ranchers. Most of them are cobble-job artists who have no business working on their own equipment. So if you are not the original owner of your Foreman, it'd be a good practice to go over your harnesses and fix any connections that are cobbled or connected into the wrong circuit (check your winch wiring or add-ons if ya got any). All add-on wiring connections should be soldered and waterproof sealed up.

 

 

Right, an open or shorted diode has nothing to do with how the motor runs, it only functions the moment you release the starter button.

 

You can check the diode after you remove it from the fuse box by setting your multimeter to Continuity mode, or Resistance mode. Then touch each of the two diode terminals with your two multimeter leads and note whether the diode conducts or not. Reverse the two multimeter leads on the diode terminals to note if the diode conducts or not in the opposite polarity.

 

A good diode should conduct current flow in one direction only.

So if your diode conducts in both polarities the diode is shorted (depending on the ATV model a shorted diode may result in a no spark - no start condition).

If it does not conduct in either polarity the diode is open circuit (which allows flyback voltage to discharge into the CDI and/or shift ECM if equipped).

Only if the diode conducts in one direction, but does not conduct in the opposite direction, is the diode a good one.

i am the original owner and havent done anything to wiring in a long time and havent found any shorts to ground.

[trailcutter 13]

so found out engine will run with light fuse pulled,it just controls the lights and starter button.