Help! ST1100 misfiring when Hot

[conmac065]

Hi I am Irish traveling US on 1997 ST1100. I am heading towards Auburn, when the bike is in heavy traffic its tends to misfire. Runs great on open road 50 plus mpg. It is the California 1997 model with evaporate system ect. I need to bring the bike to a mechanic who knows about these bikes. Can anyone please recommend a shop/mechanic in the Auburn CA area who I could bring the bike to.
Regards
Neil

 

[Upt' North]

Hi I am Irish traveling US on 1997 ST1100. I am heading towards Auburn, when the bike is in heavy traffic its tends to misfire. Runs great on open road 50 plus mpg. It is the California 1997 model with evaporate system ect. I need to bring the bike to a mechanic who knows about these bikes. Can anyone please recommend a shop/mechanic in the Auburn CA area who I could bring the bike to.
Regards
Neil

Neil, have you checked the RAN list on the riding drop down. That would be a good start.
I would also change the subject to HELP! No I'm not kidding.
My initial thoughts would be the fuel vacuum valve, or a plug or a coil.
Upt'North.

 

[Upt' North]

There are 8 on the RAN list for CA.
Upt'North.

 

[Upt' North]

@Mellow could you change the subject to Help Joe. I see Neil is a new member and may be struggling.

 

[conmac065]

Thank you Upt' North what is the RAN list can you send me the link please. sorry new to the forum

 

[Nashcat]

Link to ran list

https://www.st-owners.com/forums/pages/RAN_US/

 

[Upt' North]

As per John, but it's on the riding drop down on the top line. It's like minded ST'ers who'll go the extra mile to help.
Good luck fella.
Upt'North.

 

[conmac065]

Link to ran list

https://www.st-owners.com/forums/pages/RAN_US/

Thank you

 

[ST11Nut]

When you mention heavy traffic, do you mean low speed stop and go traffic where the engine RPM is low vs, the open road where the RPM is higher?

I had a ST1100 that would misfire at the low RPM range but seemed to run fine at higher RPM. It turned out to be the coils. I swapped in a spare set I had from a parts bike I had at the time and it completely fixed the problem.

I hope you get it fixed soon so you can get back on the road

 

[Upt' North]

Is it happening when the fuel level is low, that could be a sign of an overheating fuel pump.
Upt'North.

 

[Smudgemo]

I don't know what to suggest, but it's hot AF in the valley right now, and the traffic at certain points in Sacramento is always stop and go on I-80. It should run fine in spite of that, of course, but once you clear the Sac area, the traffic will stop being an issue.
Just out of curiosity, any photos of the bike? I fixed up and sold a '97 just about a year ago to a nice fella who I wouldn't be surprised to find out sold it. I kept record of the work I did which could potentially eliminate a bunch of things if you happen to own it now. Are the front turn signals clear? Is the rear shock a Hagon with a red spring? The old Givi box had a metal luggage rack mounted to the top. It was non-ABS.

 

[conmac065]

I don't know what to suggest, but it's hot AF in the valley right now, and the traffic at certain points in Sacramento is always stop and go on I-80. It should run fine in spite of that, of course, but once you clear the Sac area, the traffic will stop being an issue.
Just out of curiosity, any photos of the bike? I fixed up and sold a '97 just about a year ago to a nice fella who I wouldn't be surprised to find out sold it. I kept record of the work I did which could potentially eliminate a bunch of things if you happen to own it now. Are the front turn signals clear? Is the rear shock a Hagon with a red spring? The old Givi box had a metal luggage rack mounted to the top. It was non-ABS.

Hi
I have the bike few years. My friend who stored it for me in Santa Fe passed in March and I am driving the bike from Sante Fe to Auburn. when I hit heavy traffic it started Mis firing.
I am going trt and head early wed morning when it’s quite and cool. hopefully I can make auburn . If I can do that I’ll throw everything at it. IM trying to think what could be causing it to misfire when it’s hot. All the way over it was doing over 50 mpg and running sweet . I
Just need a mechanic who knows pans in the area

 

[Nashcat]

@conmac065 Are you sure that you haven’t put the wrong grade of fuel in the tank? A tank of E85 would cause problems. Lots of strange grades sold in CA.

 

[bdalameda]

Misfires are usually related to lean conditions or electrical.

1) Take a look at the sparkplugs as well and see if you have a fouled plug or indication of a bad plug. You may want to replace the plugs for good measure - there are plenty of counterfeit NGK sparkplugs out there that can cause odd misfires.

2) In really hot weather especially on the ST1100 in traffic, the fuel in the tank can get pretty warm if not hot. This can play havoc with the fuel pump as well as the vacuum fuel shutoff valve as it can get vapor locked and the fuel pumps can be intermittent when running in hot fuel. I would bypass the vacuum valve if you have not as yet. When it misfires try cracking open the fuel cap and see if this helps. Applying a little pressure to the fuel tank can show you if you have a bad or poor performing fuel pump, though this can be difficult to do without a plug and hose to the fuel cap spigot that you can blow into.

3) Remove each plug cap and clean the inside and top flange cover thoroughly with electrical cleaner and microfiber cloth. Usually cold weather can cause misfires with carbon tracings developing in the plug caps but perhaps in very hot weather this can happen. Check that the plug caps are seated into the wires. The plug caps have a screw terminal that screws into the plug wire to make contact. Sometimes unscrewing the plug caps from the wire and cutting the wire off and re-screwing the caps into the wire can fix a poor connection.

 

[conmac065]

Misfires are usually related to lean conditions or electrical.

1) Take a look at the sparkplugs as well and see if you have a fouled plug or indication of a bad plug. You may want to replace the plugs for good measure - there are plenty of counterfeit NGK sparkplugs out there that can cause odd misfires.

2) In really hot weather especially on the ST1100 in traffic, the fuel in the tank can get pretty warm if not hot. This can play havoc with the fuel pump as well as the vacuum fuel shutoff valve as it can get vapor locked and the fuel pumps can be intermittent when running in hot fuel. I would bypass the vacuum valve if you have not as yet. When it misfires try cracking open the fuel cap and see if this helps. Applying a little pressure to the fuel tank can show you if you have a bad or poor performing fuel pump, though this can be difficult to do without a plug and hose to the fuel cap spigot that you can blow into.

3) Remove each plug cap and clean the inside and top flange cover thoroughly with electrical cleaner and microfiber cloth. Usually cold weather can cause misfires with carbon tracings developing in the plug caps but perhaps in very hot weather this can happen. Check that the plug caps are seated into the wires. The plug caps have a screw terminal that screws into the plug wire to make contact. Sometimes unscrewing the plug caps from the wire and cutting the wire off and re-screwing the caps into the wire can fix a poor connection.

Thank you very much bdalamedaI will take that advise and try tomorrow. I leave very early in the morning as temps are very high tomorrow. Hopefully I can make Auburn. Ive ordered a new set of spark plugs a fuel filter and two sets of coils plus the carb boots being delivered to an auburn address. I'll bypass the vaccuum valve as advised. I really appreciate your advise

 

[conmac065]

@conmac065 Are you sure that you haven’t put the wrong grade of fuel in the tank? A tank of E85 would cause problems. Lots of strange grades sold in CA.

Don't think so but I'll you up tomorrow just in case.

 

[Slydynbye]

Simple easy STuff to check
Battery Terminals tight?
Check the fuel filter for any water.
Also check the red wire for heat marks.
Take a peak at the plugs?
Ground connection behind the grab handle clean and tight?

 

[conmac065]

Made it to destination
I’m fairly sure the issue is ignition coil or lead on right side of bike. Went to bypass vaccum fuel stop as advised but found some previous owner has already removed it. Fuel filter doesn’t look great so that’s on that way as well with new air filters
That you all for help
I’ll let you know if the coil solves the issue

 

[Upt' North]

Made it to destination
I’m fairly sure the issue is ignition coil or lead on right side of bike. Went to bypass vaccum fuel stop as advised but found some previous owner has already removed it. Fuel filter doesn’t look great so that’s on that way as well with new air filters
That you all for help
I’ll let you know if the coil solves the issue

Good luck and well done.
Upt'North.

 

[Smudgemo]

I think just to be sure it's not the fuel pump experiencing a heat-related issue, it might be worth a look when you have time. http://www.st-riders.net/index.php?topic=1033.0
My '96 was mid to low on fuel last summer in the UT mountains on a very warm day, and I stopped repeatedly on the way up to take pictures. On the back side it started dying until it just wouldn't run. I suspect my pump got heat-soaked and lost function because after an hour or so it started and ran fine all the way home. Even though it was hot in the desert, I kept the tank level up and never got stuck in any traffic situations and got home with no further problem. Admittedly I did not test my pump, I just replaced it.
I feel like stop and go around Sac in the heat that day would have done the same thing to an iffy pump. If you decide it's the pump, you can spend big and buy a new one, or you can buy a quantum pump and hack the existing system utilizing the pressure bypass. I did the hack on a '97 I used to have, but while it worked fine, I never kept it long enough to know for sure long-term. You can see the hack here: https://www.st-owners.com/forums/threads/300-97-st1100-refurb-thread.176503/page-5#post-2316998
Just something to think about if the other testing you do comes up fine.