I have a problem with the engine falling away from idle when it is hot - hotter than average.

Under 80F, I don't have a problem at all. Above 80F, especially if I have been involved in a series of traffic lights or stop and go traffic, the engine want to die. I have to keep blipping the throttle to keep it alive.

I have replaced the fuel pump and filters as part of an ongoing maintenance program. Ditto the spark plugs. I have the fuel pressure regulator and vacuum hose on-hand ready to replace also.

I'm wondering if the coils, when hot, have a break that opens up. The bike runs fine past idle.

Any thoughts??


Cheers, M

hmm interesting issue moto ....

i wonder if your plugs are the right heat range .

quite a few of us use ngk d7ea ....unfortunatly i dont have a cross reference to other brands

as to the coils having a crack ,,,,,maybe this could be tested in a darkened garage or similar ...undo the coil covers and you should be able to see any high voltage spike arcing over along the high tension path

i recall that there has been made note that the hall effect sensors could become unstable with temperature

there is a testing tecnique in the "efi trouble shooting" thread-weblinks by bert ....found on the "portal page "

i guess a hair dryer could localize heat affects for this testing

i would also check the fuel cap seals and breather tubes for being "open" could heat be affecting the fuel supply by vapour lock issues in or around the tank ?

Usually when it`s heat related problems with hall sensors, the engine cuts completly the affected cylinders.

Vapour lock? Could be a idea to try to wrap the fuel lines with some heat isolating stuff?

Inge K. wrote:Usually when it`s heat related problems with hall sensors, the engine cuts completly the affected cylinders.

Vapour lock? Could be a idea to try to wrap the fuel lines with some heat isolating stuff?

+1 (I think the same)

[quote="charlie99"]hmm interesting issue moto ....



there is a testing tecnique in the "efi trouble shooting" thread-weblinks by bert ....found on the "portal page "

I looked at Bert's EFI sheet - that was definitely a labor of love. Thank you!

I think that I need to test fuel pressure when the vehicle is hot as my next move.

Cheers, M

[quote="charlie99"]hmm interesting issue moto ....

i wonder if your plugs are the right heat range .

quite a few of us use ngk d7ea ....unfortunatly i dont have a cross reference to other brands

I removed some Autolite plugs 4153 from the bike last Saturday - not because of heat range, but because I was replacing old with new.
I put in Bosch plugs.

The autolite plugs convert to boschXR4CS

Now I'm going to have to wait for a 80 degree day to see if that solved the problem.

Cheers, Mark

Moto Smith wrote:The autolite plugs convert to boschXR4CS

If you got the genuine HT leads and caps, you should use Bosch X5DC.
If you got non genuine caps w/o resistors, the XR type is correct.

[quote="Moto Smith

I removed some Autolite plugs 4153 from the bike last Saturday - not because of heat range, but because I was replacing old with new.
Cheers, Mark[/quote]

what did the electrodes look like mark ? black white or golden ?

old school mechanics always looked there first ...

charlie99 wrote:[quote="Moto Smith

I removed some Autolite plugs 4153 from the bike last Saturday - not because of heat range, but because I was replacing old with new.
Cheers, Mark

what did the electrodes look like mark ? black white or golden ?

old school mechanics always looked there first ...[/quote]

The plugs looked great - a nice tan color.

OK, so today I ride 150 miles in 88F with an hour thru a city and not a problem.
The only thing that I've changed in recent history is the spark plugs...

Cheers, M

well thats a start ....what about the fuel load whilst doing this ?

did i see in here some one got 3/4 full tank and the issues started .....from memory he solved it with replacing the fuel tank lid seals

just a thought

charlie99 wrote:well thats a start ....what about the fuel load whilst doing this ?

did i see in here some one got 3/4 full tank and the issues started .....from memory he solved it with replacing the fuel tank lid seals

just a thought

Yes, that was me. I had a perimeter crack around the valve of the cap and replaced the whole cap.

I have the fuel pressure reg that I will change out in the near future - that will make pump, filters and reg all replaced as part of preventative maintenance.

Also, my MPG just increased with the new spark plugs - I don't know what happened there, but I'm getting about 4-5 more MPG.

Cheers, M

hey.... thats a great result ...

Moto,
Quote:- "Also, my MPG just increased with the new spark plugs - I don't know what happened there, but I'm getting about 4-5 more MPG."

If you change your plugs ten times, will your tank overflow?

Paul.

sidecar paul wrote:Moto,
Quote:- "Also, my MPG just increased with the new spark plugs - I don't know what happened there, but I'm getting about 4-5 more MPG."

If you change your plugs ten times, will your tank overflow?

Paul.

I don't know about the tank overflowing, but I should be near to 70 MPG following that logic.

I wonder what will happen if I change the oil filter again?

Cheers, M