Honda ATV Forum banner

420FM, no spark, no FI or Temp light when key it switched on

21K views 48 replies 8 participants last post by  D61 
#1 ·
Got on the 420FM today to move it. It fired right up in Neutral, but didn't want to catch in 1st. It fires right up in R, N, 2-5, but would not catch in first.

Of course, with my OCD, I couldn't just leave it, so I pull it under the carport and put it in first, pull the plug, ground it on the head, and turn it over, discovering what looked like a good spark. Put plug back in, turn it over, nothing. Try it in Neutral, nothing.

Pull plug again and ground it to head, no spark.

Now I notice that when I turn the key on, the FI and Temp lights aren't cutting on for a second like they usually do.

Check fuses, they're fine. Swap new ones in just in case, no change.

Nose around on the interwebs, see that if you are turning one over with the plug not really well grounded, you can fry a CDI, so I think maybe that's it.

Go back, pull CDI off of other Rancher, put it on, no change.

Now I'm frustrated, irritated, and here asking what the problem is. Anyone got any idea what to look at?
 
See less See more
#2 ·
Jeep: Are you sure that the cylinder is getting fuel? If so, then you could be having a problem with your ECM (the vehicle computer) since your dash lights are not testing properly when you first turn on the ignition. Try disconnecting the positive leads off of the battery for a minute or so, then reconnect the leads and see if things look any better. Are you also certain you have a good battery? Try jump starting it and see what happens.
Good luck sir.
 
#3 ·
Hooked a booster pack up to it to make sure it has juice. No change.

The FI and Temp lights not coming on tells me it's not initializing. No spark when I ground the plug on the head and turn it over, and I dont think it's getting fuel either, because it doesnt appear that the EFI is initializing when I turn the key on.

I'll try unhooking the batt tomorrow when I head out to work. Something tells me it won't be that simple.
 
#7 ·
I would say your not getting power from the battery to the ignition switch ?..for some reason..your lights are not coming on..any of them ?.this tells me a bad ground ?..bad ignition switch ?..or blown fuses ?. you need to see if your getting power from the battery to the ignition switch ?..and back out the ignition switch ?. does the lights even come on ( headlights ) ??..if not ?..your not getting power to both in..and out the ignition switch...this is what I see here.
 
#8 ·
When I turn key on the neutral light lights up, starter button turns motor over fine, lights work, 4wd indicator lights up when I switch it into 4wd. Just no FI or Temp lights. I have a bad feeling it's the ECU.

I tried unhooking the battery for a bit, and swapped the FI relay from the 420AT I have. No change. The ECU's are different and now I've swapped fuel injection relay, coil, and CDI over, but I think the problem is the FI and ignition systems aren't coming on, so those components were all further down the line from the problem.
 
#9 ·
Just got through with the voltmeter. On page 6-8 of the manual there is a wiring diagram. With key turned on I have 2 volts coming out of the ECU on terminals B1, B33, B11, which are the "Main", "Inj", and the third is the wire going to the coil.

I did find it interesting that I showed 19 volts to the Bank Angle sensor on the two hot wires.

That point to bad ECU or can anyone think of anything else to check?
 
#11 · (Edited)
Yeah. Checked them about 5 times. They're good.

I actually had a good fuse in one of my 500's, but it wasn't making a good connection with the "out" wire coming out of the fuse box, so while the fuse was good, it was only connecting with one side of the wiring harness, so fuse tested good, but current was going into the fuse, and not coming out of the fuse.
 
#12 ·
Tried messing with the bank angle sensor again, can hear the fuel injection relay clicking when I unplug and replug in the bank angle sensor.

Can also hear the relay clicking when I pull the main 30A fuse and the 10A fuse, so apparently power is at least getting to the relay and that confirms that power is moving through the fuse box correctly.
 
#13 ·
OK, looking at page 6-8 of the manual, the brown wire from fuel injection relay runs power to fuel pump. Has + coming out of relay, does not have + at fuel pump.

That brown wire is tied into the green and yellow coil wire, and also with the Green and brown wire going to the injector, and aloso with the black and red wire going to the coil

I jumped the green and yellow coil wire to the + on the battery and the fuel injection relay started rapidly clicking.

Pretty much I've eliminated the bank sensor, the fuel injection relay, and the wiring there is ALL tied into the ECU.

I hate to drop $160 on an ECU and find out it's not the problem, but at this point, I don't know what else it could be.

Anyone have any more input before I put the order in?
 
#14 ·
try tapping on the ecu with the spark plug out..and laying on the head...and crank it as your tapping it..and watch for spark ?. if it sparks at any time ?..then yeah..i'd say your ecu is bad.
 
#15 ·
Now I'm at a TOTAL loss. Got new PGM-FI unit in from Paulie. No change. When I turned the key on and the FI and Temp lights didn't come on I wanted to puke.

I'm running out of electrical components to check here.

Anyone have ANY idea what could cause this? Battery is good, fuses are good, fuel injection relay clicks when I turn key on or pull ignition or main fuse. What other than the PGM could keep power from going to the ignition and fuel pump?
 
#17 ·
Place a wire from the + on the battery to Black/Red on the ign. coil -- leave the Black/red on the coil just shove the wire in beside the push on terminal.
 
#18 · (Edited)
I jumped the green and yellow coil wire to the + on the battery and the fuel injection relay started rapidly clicking (couple of days ago)

From the attached diagram, it looks like the brown wire coming out of the fuel injection relay ties into the Green/Yellow coil wire, and also goes to the fuel pump. Since I have 12V coming out of fuel injection relay on that brown wire, but no power to fuel pump, I tried jumping 12V to that circuit, and I got a rapid clicking from the fuel injection relay.

So you're saying try 12V to the red/black wire on the coil?
 

Attachments

#19 ·
The green/yellow wire is the ground side of the coil which is pulled to ground by the PCM, which is pulsed from the PCM. Using a jumper from the Battery + to the black/Red on the Ign. coil with the Black/Red wire still on the coil -- it bypasses the bank angle sensor and the engine stop relay.
 
#21 ·
OK, progress, but going to have to come back to it in a bit. Gotta take kids swimming and then have a date with the woman.

Jumping 12V to red/blk coil wire initializes it, but still won't start. Both FI and Temp lights come on momentarily like they are supposed to, and I hear the momentary noise that I think is the fuel pump.

What does that tell me? Thanks. Can't tell you how relieved I was to finally see those lights blink on and hear that little noise.
 
#22 · (Edited)
That tells you either the stop relay is bad or the bank angle sensor is bad. It proves that you fuel pump relay is good. You may have a blown fuse or Ign. switch could be bad. Do you have spark?
 
#23 ·
If it has spark and fuel like your sayin it should start.
 
#26 · (Edited)
Okay remove the jumper and unplug the bank angle sensor -- on the harness side of the bank sensor jumper the red/white wire to the neg. of the battery and try starting the bike. Do this first unplug the stop & fuel relay, they are both in one relay, back of the battery -- with the key on see if you have 12VDC on the Black/Green wire.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top