Jump to content
SpecialEd

Sudden Power Failure

Recommended Posts

Hey, y'all--

My brother's six-year-old Harley ElectraGlide suddenly lost power during a recent ride. I followed him in my car as he rode it up to a local repair shop, and the exhaust reeked of unburnt fuel. The bike struggled to climb even modest grades in the roads, requiring him to downshift into a lower gear. The exhaust note sounded very "tinny." 

The shop recommended that he run sea foam thru it in order to clear any possible gunk from the injection ports. Does this sound legit??? Any diagnostic opinions welcome.

Share this post


Link to post
Share on other sites

Not the first thing I'd try. If you can smell the fuel, it's flowing but it isn't igniting. Might be electrical problem, might be the spark timing. Check the plugs first. See if both are the same (for a Harley with the rear cylinder hotter) correct color. See if one or both are wet from not fully firing fuel. How many coils it got? One? Might want to check the coil with a VOM for correct resistance on both sides.

edit: an easy way to see if one cylinder is goofed is to check the temps of the exhaust right after it starts up. Don't touch it, but put hand up there and see if one warms up way faster than the other.

Edited by ReconRat

Share this post


Link to post
Share on other sites

Agree, pull the plugs and look at color. If any look wrong check for spark on that wire.

Share this post


Link to post
Share on other sites
12 minutes ago, Tonik said:

Agree, pull the plugs and look at color. If any look wrong check for spark on that wire.

Get a pair of plugs too. Might need them for getting it all back in order. You can always put the old ones back in and keep the new ones as spares. Also check to see if it's the right plug, you never know...

edit: If you're really cheap like I used to be, and it's only one plug looks bad, swap the plugs between cylinders and see if the problem moves. Then it's either a plug or the firing of a plug.

Edited by ReconRat

Share this post


Link to post
Share on other sites

My brother Steve has the bike back for now, but reported that though it ran okay for a while it backfired a lot on his way home from the shop (about 5 miles away) and then began acting up again. It's still not running right; apparently all the mech did was load it up with sea foam and tell him to ride it to clear possible fuel obstructions--at least that's what Steve told me they did. 

This seems rather unethical on the mech's part; I'll forward all your advice to him and try to get up there to help with diagnosing this, or simply suggest he ride it over to the nearest HD dealer, which he probably shoulda done in the first place.

Thanks for your help, guys.

Share this post


Link to post
Share on other sites

BTW, doesn't excessive backfiring indicate that the bike is running very lean fuel-wise? I seem to remember that this causes heat damage to the pistons, rings, and connecting rods.

Share this post


Link to post
Share on other sites
1 hour ago, SpecialEd said:

BTW, doesn't excessive backfiring indicate that the bike is running very lean fuel-wise? I seem to remember that this causes heat damage to the pistons, rings, and connecting rods.

Yes but it has to be pretty bad and go on for awhile.

  • Upvote 1

Share this post


Link to post
Share on other sites

unburned fuel in the exhaust can be a backfire when and if it detonates. Or in the case of old Toyotas, it can fragment the catalytic converter into little pieces and lift the car several feet off the ground...

Share this post


Link to post
Share on other sites
1 hour ago, ReconRat said:

unburned fuel in the exhaust can be a backfire when and if it detonates.

This happens with my John Deere tractor quite frequently, to the point where when I'm done mowing and shut off the ignition, I'm actually surprised when it doesn't backfire *loudly* a few moments later.

We are taking Steve's bike up to the Mentor HD dealer tomorrow morning. I will be sure to post what their mech says was wrong with it after we get it back.

Share this post


Link to post
Share on other sites
11 minutes ago, SpecialEd said:

 I will be sure to post what their mech says was wrong with it after we get it back

And we will be sure to pretend we give a fuck.

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

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×