[JPelletier]

Hi,

I got a 1991 TRX350D foreman for cheap, it was stored for 3 years after an electrical short circuit with the winch cable.

I've replaced fuses and now I have power (lights turn on).

Now I have 3 known issues:

1. No spark at spark plug
2. Fuel pump not starting (no power)
3. Starter work sometimes, (after feet kick-start it usually work). Need to be replaced.

I have another trx350 but 1986, so I switched Fuel Relay but I still have no power at fuel pump. I also jumped wires in the red connector and the pump work.

So:

• Fuel relay is working
• Pump is working when jumping red connector
• NO POWER at fuel pump
• No spark at plug
• All fuses are good

So you this it's the CDI Unit or it could be something else? It's not cheap so I don't want to change it for testing...

Thanks a lot for help

 

[SamUK]

@Goober should be able to offer some assistance

 

[JPelletier]

I think it's normal to have no power at fuel pump if Ignition is not working.

I will test stator / pulse generator / Ignition secondary Coil resistance this weekend

 

[Goober]

is the battery new or old? It must pass a load test.

You will have to take off the battery/toolbox and inner fenders to do more checking. If you continue to have problems I would remove the front fender and rear fenders to examine the condition of the main and all subharnesses.

Yes i think you’re on track following ignition sequence. Check all connectors and for continuity first. check stator for continuity and resistance you may find a stator fault

The foreman ignition module CDI, stator, starter switch are not interchangeable with the Fourtrax, so don’t risk the swap.

when you switch on are you getting a steady neutral light and is the oil temp light coming on momentarily and then it goes out?

ground the temp sensor lead to the footpeg—you should get a steady oil light and the fan should come on. If fan does not come on, inspect the wiring to ensure the FCU is mated properly.

yes kick starting is ok. On the 86, you have to get the stator excited to get fuel pump running. On the Revolution Research Line, the ignition sequence is explained to my understanding the CDI controls the function.

look for power at the CDI if power is there you may suspect the CDI. However don’t bin it yet

 

[JPelletier]

Wow thanks a lot for your answer, I will remove fenders and inspect everything.

Yes neutral turn on, oil too and then turn off.

Battery is brand new, and fully charged.

 

[Goober]

I pulled my project 86 into the garage
Here’s 3 pix
First is the stator connectors and plug—stator has 3 yellow wires going to the regulator; 86 has 3 additional wires E (exciter coil, ground, and Pulse Gen— you don’t have an exciter coil). But you’ll have a blue/yellow pulse gen and a green ground wire
Left inner fender is the FCU and connector set.
Right inner fender is connectors for starter switch, gear change indicator subharness, CDI and ignition (master) switch. Continuity check the RUN/OFF switch on the Fourtrax you have no continuity/continuity; on a Foreman you have continuity/no continuity. Just in case someone put the wrong start switch assembly
Just remember your wire colors are gonna be different colors than mine

 

[JPelletier]

Thanks a lot, this will help for sure! I have the foreman 87 wiring diagram for wire colors but mine is 1991, might be different. I can't find service manual for 91

 

[JPelletier]

@Goober Do you know what are differences between 1989 and 1991 foreman?

When I compare:

• https://www.cmsnl.com/honda-trx350-fourtrax-1991-m-canada-sul_model5285/partslist/F__2800.html
• https://www.cmsnl.com/honda-trx350d-fourtrax-foreman-4-x-4-1989-k-usa_model7572/partslist/F++28.html

Only difference I seen in part number is the Wire Harness (14), why they changed harness if everything else is identical :S

[EDIT] I think I compared wrong diagram, wait I have to compare again haha

 

[Goober]

Hey JP
There may not be a difference—to my understanding the 88-93 TRX350D should all use the same parts and service manual. I will give it some thoughts though.
is everything testing out? Did the fan work when you grounded the oil temp?
Test the RUN/OFF circuit

if you’ve tried everything maybe dry out the CDI in an oven. Connector side up at no more than 200F for no less than three hours. Let it cool completely before you take it out and install. You just want to dry it out not cook it

 

[JPelletier]

I could not work on it yet, but I've done a nice SpreadSheet comparing 1989 and 1991 TRX350 based on cmsnl website. https://docs.google.com/spreadsheets/d/1ToOpKCz3GZmgh8z2zH4U0zst0z0llxERNw44Nb3SZmo

Based on that, I confirm that Wire Harness do have a different number, but other than that it's identical. Maybe they changed some wire colors?

1991 Honda seems to have an additional Ignition Coil in the wire harness picture, any idea why?

 

[Goober]

From what i can see the 7 coil was superseded by 8 coil, which is a non-OE part, which is round.

the 16 fuse panel application seems to have 8 fuses with one being a 30A fuse separate from the fuse panel

 

[JPelletier]

I got some time to test my atv tonight

1. Ignition Coil is good, I've switched with my 86 trx to confirm
2. CDI have power when Ignition is on and killswitch at run
3. CDI wires continuity tests are good
4. Pulse generator resistance is good, tested at CDI connector AND connector near fuel switch.

I'm not sure I did the good tests for stator / revolution line. Which side of the 3P connector I must test? Female or Male?

 

[Goober]

Test the stator side not the reg/rec side. Yellow to yello should get 0.6 ohm? Three times.
Make sure to inspect that big fuse

 

[JPelletier]

You mean the fuse in your last image, main fuse? I already changed it, without it there is no voltage anywhere on the atv

 

[Goober]

Here’s me testing the pulse gen on my stator. Shows the connector with the three yellows you want to test. Your Foreman connector is white the Fourtrax is green
These circuits must have a little resistance (i think 0.6 ohm at 25C) but must not be shorted or open.

 

[JPelletier]

My connector is green too. I got .2 /.3 ohm but temperature is -10C

Below you can see my Stator test, also tested that I have No continuity with ground. (I realized that my Mastercraft meter does not work well under 1 ohm)

Pulse Gen test:

And the test I dit on CDI wires:

 

[Goober]

Ok fan control unit test:
ground the temp sensor lead to the footpeg—with master switch on—you should get a steady oil light and the fan should come on. If fan does not come on, inspect the wiring to ensure the FCU is mated properly.

if the fan works, then take the CDI and dry it out in an oven. Connector side up no more than 200F. At least 3 hourd. Leave it in the oven until cool. You’re trying to dry out any moisture or film on the circuit biard

 

[JPelletier]

Perfect will do that.

I've been searching for similar issue, and someone said it was the caused by a defect voltage rectifier/regulator. If the one on my 1986 is compatible it's easy to test.

Do you think it's compatible? They have a different product number, but superseded by the same product number.

1991(left) vs 1986 (right)

I've already tested voltage on Wiring harness side connector, was good.

 

[Goober]

Yeah good you pointed that reg/rec supercession out. Don’t know why it wouldn’t work.

if the FCU doesn’t make the fan come on, then there’s a method that explains how to power the fan in a way to ensure the fan motor works.

you can dry out the FCU with the same method i used to dry out the CDI

 

[JPelletier]

Tonight I've replaced the Starter successfully.

I also tested my rectifier using this method:

and I have continuity (0.55) when I should and no continuity when I should not. So rectifier seems good. I've not switched over, tried to avoid having to dissamble everything lol

Wanted to do the fan test but not sure how,is it with one of those cables?

Thanks again for your help