Jump to content
Sign in to follow this  

How likely is a coil failure on an 05 CRF450X??

Recommended Posts

Bike ran great. Installed vapor and drove around a little to check all gauge functions, everything works w/no problems. The following day I started it an let it idle for a bit before I was going to take it out for a ride. I lean it over to pick up the kickstand to back it up and in the process it dies. That day it restarted two other times but only ran briefly as I'm pretty sure it was flooding out. In the process I hurt the battery so I got a brand new one, cleaned the plug, put it back together and it started and idled for a bit and then died again just like before. I checked the spark and it appears to pulse properly but it's really weak. Coil resistance measures good. All electrical connectors appear to be in good shape etc. I did a bunch of reading(online+service manual) Although it checks out, I'm throwing a coil at it when it arrives. It seems purely electrical, when it has died it's like you just flipped a switch. Anybody care to comment?? Any input would be appreciated.

Share this post


Link to post
Share on other sites

check the wire going from the vapor to the coil. I personally dont have much experience with the vapor but a buddy has one on his bike and at one time clipped a tree limb that hit the front number plate hard enough to punch a small hole in it. the bike ran fine until the next ride when it would just randomly shut its self off. after fighting it all the way back to the house we found that the coil to vapor wire had been pinched and was shorting out. Check all your wires. Its a bear like all electrical problems but I imagine coils arnt cheap...

Share this post


Link to post
Share on other sites

Coil is $50 delivered. First thing I did when it died was unplug the tach signal wire from the Vapor, never changed anything. I had that same thought, I've seen that happen w/cars before.

Share this post


Link to post
Share on other sites

Problem areas:

Kill switch: it can work and still cause problems

Clutch override switch: wire it out

Ground wire under tank: it gets loose

Molex plug behind headlight: it gets loose

Battery ground at battery: it gets loose.

Share this post


Link to post
Share on other sites

I put a new kill switch on it, mine had been shady, had to push it real hard. What is a Molex plug?? I will check the others tonight.

Share this post


Link to post
Share on other sites

Every 'square' termination in the harness is a molex plug.

The group of three at the left end is behind the number plate

The two 'loose' wires in the middle are the usual ground failure 'loose' points

The plugs at the right are under the seat/behind the left side panel and can come partially unplugged, as do the friction plugs for single wires.

HJ07050015047.gif

Share this post


Link to post
Share on other sites

Might check the plug cap connection while you're at it. Those can corrode a bit and cause a bad connection. You'll replace it with the new coil but it might be worth checking out anyway.

Share this post


Link to post
Share on other sites

Checked Molex plugs again, ground below tank by coil, main batt. ground on both ends, clutch switch (I assume you mean at top by kill sw.) but don't see anything out of wack. However, the son-of-a-bitxx decided to run tonight. Too late to take out but oh well, I guess I'll see how far I can make it tomorrow. Thank you guys for your help, we'll see what tomorrow brings.

Share this post


Link to post
Share on other sites
Checked Molex plugs again, ground below tank by coil, main batt. ground on both ends, clutch switch (I assume you mean at top by kill sw.) but don't see anything out of wack. However, the son-of-a-bitxx decided to run tonight. Too late to take out but oh well, I guess I'll see how far I can make it tomorrow. Thank you guys for your help, we'll see what tomorrow brings.

You probably wiggled something just right.

Share this post


Link to post
Share on other sites
Problem areas:

Kill switch: it can work and still cause problems

Clutch override switch: wire it out

Ground wire under tank: it gets loose

Molex plug behind headlight: it gets loose

Battery ground at battery: it gets loose.

Every 'square' termination in the harness is a molex plug.

The group of three at the left end is behind the number plate

The two 'loose' wires in the middle are the usual ground failure 'loose' points

The plugs at the right are under the seat/behind the left side panel and can come partially unplugged, as do the friction plugs for single wires.

HJ07050015047.gif

Might check the plug cap connection while you're at it. Those can corrode a bit and cause a bad connection. You'll replace it with the new coil but it might be worth checking out anyway.
You probably wiggled something just right.

Yes, yes, yes, and yes! I've had everyone of these problems on my 450x at one time or another! 👍

Here's another short list:

1) While removing the tank to change jetting the pet-cock must have bumped the coil wire removing it from the coil = no start = hours of investigation

2) Fuse 'sorta' blown = jump started the bike one day = slightly blown fuse = would randomly start = got lucky as this was the first thing we checked

3) Tank foam got into fuel line and clogged Brass elbow in carb. Run ok until WFO then would just randomly die = fuel starvation = Not good for hill-climbs = Hours of investigation

4) Spark plug wire broken = That thing just always seems to be in a bind, and putting it in and out, and the heat from the head, etc... = not start, or just run crappy = only a few minutes to check

Good luck with the test ride! Don't go too far from home yet! 🤣

Edited by NewMexican
Oh yeah that other one too...

Share this post


Link to post
Share on other sites

4) Spark plug wire broken = That thing just always seems to be in a bind, and putting it in and out, and the heat from the head, etc... = not start, or just run crappy = only a few minutes to check

i've actually seen the insert in the plug wire..(the metal contact unit that connects to the spark plug) ..unscrew, causing intermittent starting/running issues as well...

Share this post


Link to post
Share on other sites

Okay it starts and runs for approx.4 minutes then dies. It did this today twice exactly the same each time. Come to think of it, that's been pretty consistent when it dies. Is there anything ignition or fuel related that changes after a set time? The first time it died it was 153F, the second it was 188F. I was thinking that something must be cutting out when it gets hot but it really seems to be more about the length of time it runs. I know it sounds crazy but that is the closest thing to consistant I've yet to find. Anyone??

Share this post


Link to post
Share on other sites
Is there anything ignition or fuel related that changes after a set time?

vapor lock or, slightly plugged fuel filter or fuel line.

when it stalls, turn the petcock off, and check if there is gas in the bowl

Share this post


Link to post
Share on other sites

I'm going to look into the tank foam thing tonight. That makes the most sense to me since it would only stay running until the fuel in the line was spent. Also, every time I go to look into the electronics, I pull the tank which would probably dislodge the blockage. What is the fix for this? Can you replace the foam or do you replace the tank?

Share this post


Link to post
Share on other sites
I'm going to look into the tank foam thing tonight. That makes the most sense to me since it would only stay running until the fuel in the line was spent. Also, every time I go to look into the electronics, I pull the tank which would probably dislodge the blockage. What is the fix for this? Can you replace the foam or do you replace the tank?

I admit my tank-foam issue might be an rare thing, but it does sound like you might have a fuel starvation issue. I have removed all tank foam from all my bikes due to the deterioration that happens to it over time and that one time my carb clogged up with it. I did however like the way my bikes handled when I put the 'new' foam in the tanks?

If you decide to pursue this option consider some of these steps.

Step 1) Just take fuel line off carb first to verify good flow there. Point into fuel/gas can turn on for awhile (if you say 4-minutes, maybe that long just for giggles?). If no delivery problems there it would be in the brass elbow, or further down line...

Step 2) Get the carb off and completely disassemble, inspect and clean before reassembly. Use light air pressure into the 'elbow' area to ensure there is good flow thru that specific location. (actually we had to turn up the air to way over OSHA limits, like 90 psi to get all the foam out of the elbow area)🤣

Before all of this you might try riding it for your 4 min til it dies (take some tools with you), immediately after it dies turn off the fuel petcock. Then try to drain the float bowl (ie. the 17 mm nut) If no or very littel fuel comes out you have some kinda fuel delivery problem. 👍

Share this post


Link to post
Share on other sites

Well, it's fixed. I don't know what but something was blocking fuel flow between the fuel tank and the carb. I disconnected the main fuel line at the carb draining it into a gas can and sure enough, I had flow at first but after only a few seconds it dwindled to a trickle or a steady drip. I removed the fuel filter and lines, back-flushed them w/shop air and then re-tested to find that I now have full flow steadily. I put it all back together and the thrash-tested for about an hour w/no problems. Thanks to everyone for your input. New Mexican, I owe you a tall one!! Otherwise I wouldn't have made the correlation between limited running time with limited fuel availability. I guess I'll put my shiny new coil in stock.

Share this post


Link to post
Share on other sites
vapor lock or, slightly plugged fuel filter or fuel line.

when it stalls, turn the petcock off, and check if there is gas in the bowl

👍:banghead:🤣

Share this post


Link to post
Share on other sites

Okay, so I owe Amazing Recardo a tall one as well. All apologies man. Thanks.

Share this post


Link to post
Share on other sites

Just yesterday on my sons 150r The coil, cap piece that goes into head and onto spark plug cracked and grounded out the motor.Motor just died without any warning. There was a 1 inch crack in the plastic just above the spark plug. We wraped electrical tape around the crack and it fired up but was very erratic. This is a heads up for all crf riders. Also a heads up, the coil will hold a charge that will curl your hair free of charge. no pun intended.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...