fuel mileage problem

[slick]

I have a 2007 RSTD that has developed a problem. Usually it does not sit more than a few days but due to the weather and illness it sat for about 1 1/2 months in a cycle shelter outside. When I fired it up to ride I noticed that when riding with steady throttle the bike would lurch as if suddenly getting fuel. My guess was trash in Carbs. I ran the gas out put in a bottle of seafoam and filled up with premium and rode hard. The bike seemed to clear up but still ran a little flat. So I synched the carbs ( which I do at each oil change) I also checked and cleaned the air filters. Bike seems to run OK but I have noticed that I have lost about 10-12 MPG!!!! I did notice when I synched the carbs that the vent ports used for synching the carbs had a little fuel in them. Does anyone have any idea what would cause this???? I have double checked and resynched the carbs( they were OK) no fuel leaks, air filters clean. The engins seems to run ok so I don"t think that the plugs are bad, they were replaced about 4000 miles ago. Any suggestions on what else to check I really don"t want to go to the stealership but losing 40 miles per tank may be worth it if it comes down to it. Thanks for any help

[RandyR]

I'm going to guess you're running on 3 cylinders. I'd pull the plugs and see what they look like.

[1joeranger]

I also have the same exact problemto include a little noticeable fuel in the vent ports when I synced the carbs. Seafoam is not getting it and it is driving me nuts!!! Another member mentioned checking the plug caps! Which is next on my to get it done list. I check my mileage at every fuel up and ! have been running about 32mpg all winter, down 12mpg! So far I have:

 

• Changed the plugs
  
• Cleaned the air filters
  
• Synced the carbs
  
• Seafoamed the gas
  

Engine sounds good and no hesitations or whatnot. Really frustrating!!!! HELP!!!

[Cougar]

one fouled plug. my vote

[1joeranger]

Thanks!! I installed new plugs a months ago thinking that might have been the cause. I felt like there was a performance increase but my mpg did not improve. The original plugs at 25K also looked fine. I cleaned them every 8K and would still be using them now if it was not for the decrease in mpg!

 

It makes sense to me that a fowled plug would decrease the mileage by 1/4. What is the best way to check for a fowled plug?

[Yammer Dan]

Just look at them. Or you can pull wires off one at a time and see if there is any change. You will notice difference if they are firing good. No difference if not firing.

[Cougar]

The fouled plug should look wet/darker

[1joeranger]

OK Guys! Ready for Plan B!! Pulled each wire off while running the engine and noticed a difference in performance each time. So it does not seem I have a fowled plug. Still clueless unfortunately. HELP!!??!!

[Squeeze]

Check the Resistor Area in the Caps for Corrosion. Most likely you'll have a weak Contacts there.

 

You can look into the Connector where the Plug goes in and see a large brass Part with two Slots. Take a large enough Screwdriver to catch both Slots at one Time and unscrew it. There's Resistor and a small Sprind inside, both might show Corrosion at the Contact Points. Clean off the Crud, put some dielectric Grease inside and put it back togehter.

[slick]

My Issue was a fouled plug. RJALAMO I would still pull your plugs. My engine developed a miss with each plug wire removed individually while running, but when I removed the plugs I found the left rear plug was wet with gas. So I am assuming it was not firing fully. The gap was Ok so I just replaced that plug and went for a ride. My mileage was back to the normal 42MPG. Just a note I also resynched the carbs since I synched them with a cylinder not firing correctly when I was trying to figure out what was wrong. They were off slightly. All is now OK:clap2:

[First_N_Last]

did you change your rear tire recently?

[GeorgeS]

You said you replace the plugs, recently. Maby you got a sick plug. It possible to get bad new plug. Happened to me more then once.

 

Also. when installing is possible to crack the Porcilin part. ?? ( well maby )

 

Could be a sick, Ignition coil also. Did you do the Heat Test on the Exhaust pipes.

Start engine cold, for few min. then feel each Exhaust pipe, compare the Temp of each pipe, ( carefull don't get burned ).

 

If you can narrow it down to one cylinder, Change that plug again, or try one of the old ones if you still have them.

 

Also might be an Ignition Coil going bad.

 

Also, apply some Electrical Contact cleaner to the " Run Stop " switch. Hight resistance across that switch will cause a voltage drop to the TCI Unit. ( Not good )

 

I'm fishing here

[1joeranger]

I did change the rear plugs recently in an attempt to resolve the drop in mpg. So the problem was occurring before the new plugs. The old plugs looked fine. None were wet with fuel. I would not have replaced them even though they had 25k on them if it had not been for the drop in fuel efficiency.

 

I also did install a new tire on the rear (ct). I have been curious if that would affect my mpg? I believe my mpg was suffering before I did this but I am not 100% sure?

 

So what I am gonna do:

 

• pull examine, clean plugs
  
• Clean and check the resistance across the caps.
  
• Check the ignition coils. (need advice for this)
  
• apply some Electrical Contact cleaner to the " Run Stop " switch
  
• Resync carbs
  

I want to hopefully have this resolved before coming to Freebird's Maintenance Day in June! Thanks for all the great advice. I will keep posting with my results and also send pictures of the plugs!! Any other suggestions?

[BOO]

I would pull the carbs and give them a good cleaning. It wouldn't take much to cause what you have going on and while I was in there I would adjust the floats to make sure they are within limits.

As far are the Sea Foam is concerned I think it will eventually clean up your problem if it is gas related but sometimes it take a few tanks of gas for that to happen.

I might agree with the electrical evaluations if the bike hadn't sit for a while but when you have a problem after a long down period it's almost always fuel related.

If you sync your carbs so often do they have to be readjusted each time? I get mine synced every time I see George (Mechanic) which is every couple of years or so and they don't seem to change much.

BOO

[Condor]

Just a wild stab here. Runing strong but surging, usually indicates something going on with the timing. Have you checked the vacuum line going to the boost sensor for leaks???

[GeorgeS]

As Condor Says, check that line, Also pull the elecrical plug off the boost sensor, and check for Moisture in the rubber boot covering the electrical connections.

 

Any build up of moisture across the pins there can cause a high resistance to ground and effect the Voltage Level, to the TCI.

 

Also, I would consider pulling the TCI Unit, open it, and Dry out Moisture that might be inside it.

 

Also, as to the Carb Sync, Next time you re-do it, Do a complete reset on the Master, and the other three Screws, ( Back the 3 screws out so NOT makeing Contact )

 

ie: Back off all three screws, untill NOT makeing Contact. Now check the Pull cable on the Master carb. Use the Cable Adjustment to allow the Master carb linkage to go to Full Closed Position,

Then adjust the Cable for about 1/8 inch or Less of Slack.

 

Then Do the Re-Sync proceedure. After completed reset the Master so that the Cable Has about 1/16 inch of Slack. You Must have some slack there.

 

Fishing again !!

[1joeranger]

Although I did not understand half of what is being said here I do appreciate the great advice and will dive into the manual and correct my ignorance in regards to carburetors. I ride the bike every day and I sync the carbs every other month or so. So she has not been sitting any.

 

• Although I do not have any surging I will check the vacuum line going to the boost sensor for leaks as soon as I figure out what, and where, that is.
  
• I will also check the TCI unit. Again don't know what, or where, that is, but I will find out.
  
• Backing out the 3 screws? I assume that means the 3 screws that are adjusted during the carb sync? Master Carb? Full close? Yep, like a ball in high weeds here!!! Anyhow, I will study and then give all this a try!
  

Rather leery, but mostly itimadated, about pulling the carbs! Was hoping V7 Goose would adjust my floats during Don's maintenance day so I could watch and learn.

 

Again, Thanks ALL!!

[slick]

Just a wild stab here. Runing strong but surging, usually indicates something going on with the timing. Have you checked the vacuum line going to the boost sensor for leaks???

 

Just gotta ask Condor where and what is the boost valve. I cannot find it mentioned anywhere in the repair manual

[Condor]

Just gotta ask Condor where and what is the boost valve. I cannot find it mentioned anywhere in the repair manual

 

Don't know where it is on the 2ndGens. Maybe the 2's don't have one, and all timing advances are handled by the computer?? But if vacuum has anything to do with controlling timing there's got to be a vacuum sensor/converter somewhere. On the 1stGens the vacuum hose comes of the #2 manafold, but after reading about doing the Jason Mod in the tech library I see where the hose that does go to #2 carb if just left hanging, and there's no mention of it's function???

[slick]

Quick update. mileage was good for 1 tank of gas after 3 tanks mileage is off again. pulled plugs and the same one was fouled (left rear) I guess maybe a weak ignition coil. I am going to test firing voltage when I get a chance. Might try to see if I can swap the two rear coils and see if my problem moves and I'll know for sure. I'll keep info posted.

[Cougar]

1 and 3 coils will bench test fine until warmed up

just get another set from pinwall. cheap! notice

how they are set up to elements of nature when you

pull them.

good luck,

Jeff

[slick]

well tested #1 coil and it was firing at 5,000 kv when cold, and dropped out when hot. all others were at 10,000-12,000kv and work good, so I got some used coils and replaced #1, problem solved. bike has more power than it has had in a while and fuel mileage has been good for two tanks. This coil must have been going bad for a while I had been noticing that the performance didn't feel right but it wasn't until the fuel mileage got bad that I really got concerned and started checking it over. Has anyone tinkered around with making some kind of shield for the rear coils to protect them from road spray? I did put dielectric grease on the contacts to help and made sure the boots on the coil connectors were up tight, but I really don't like where these are located. I am going to try to make some kind of shield to block some of the elements. Thanks for all the help.:clap2::clap2::clap2::clap2::clap2::clap2:

[Cougar]

Nick, you let me know when you come up with a protective cover

for those rear coils. Like yours my #1 was the problem as well. I used

a truck load of dielectric grease also, it has been a year , so far all is well.

I lost my top end power when they warmed up. maybe use aluminum for

a shield? I just can not get over the fact that they did that to the rear coils.

I am glad you got it figured out, it drove me crazy for a few months.

Jeff