FJ60 rebuilt carb high idle... (1 Viewer)

NeverGiveUpYota

Dare me.
SILVER Star
Joined
Mar 28, 2011
Messages
7,018
Location
East Hampton, CT
You know what I’ve found in all my Cruiser adventures? If your clueless after trying multiple times, hand it over to a new set of eyes. It’s easy to burn out because this doesn’t come naturally to many of us. Grasping a straws won’t do it. Wether it be Jim or some other mud or not mud person, get it rebuilt not by you and let go of the stress. They’re will be something more to focus on, you know it. We all have gone through this.
Even just calling a carb specialty shop. There’s one here in CT. Guy was really cool and would have checked it out if I’d drove it to him (hour drive) but I chose to just go fully desmog carb. Once I added that thing it was like I had a brand new truck. It was so much calmer. Initially it was idling at 300, steady, so quiet I didn’t know the truck was running.
 
Joined
Oct 5, 2007
Messages
2,023
Location
Northern Virginia
You know what I’ve found in all my Cruiser adventures? If your clueless after trying multiple times, hand it over to a new set of eyes. It’s easy to burn out because this doesn’t come naturally to many of us. Grasping a straws won’t do it. Whether it be Jim or some other mud or not mud person, get it rebuilt not by you and let go of the stress. They’re will be something more to focus on, you know it. We all have gone through this.

Funny you say that, I work and while in management now, when I was a tech I had a limit on where I was in fixing and troubleshooting an issue, if I was not making headway within 1 hour, then I handed it over to someone. I learned a long time ago that if i spend hours on an issue trying to figure it out, I may eventually get it, but it was not work spending all of that time and frustration trying to figure it out. More often than not you tweaked or adjusted something or somethings so many times, getting back to a baseline was impossible.

I will say it. Send it to Jim @ TLC Performance and call it a day.
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
You know what I’ve found in all my Cruiser adventures? If your clueless after trying multiple times, hand it over to a new set of eyes. It’s easy to burn out because this doesn’t come naturally to many of us. Grasping a straws won’t do it. Wether it be Jim or some other mud or not mud person, get it rebuilt not by you and let go of the stress. They’re will be something more to focus on, you know it. We all have gone through this.
Even just calling a carb specialty shop. There’s one here in CT. Guy was really cool and would have checked it out if I’d drove it to him (hour drive) but I chose to just go fully desmog carb. Once I added that thing it was like I had a brand new truck. It was so much calmer. Initially it was idling at 300, steady, so quiet I didn’t know the truck was running.

Yeah that is precisely why I will be turning around and sending the new (to me) carb to Jim as soon as I get it. That way in another 6wks or so I will have a properly functioning and running carb and not have to worry about it from here on out (mostly).
 

FJ40Jim

The Cruiser Whisperer
SILVER Star
Joined
Sep 26, 2003
Messages
11,108
Location
Lancaster, Ohio, USA
Has anyone tried this NAPCO brand rebuild kit? Ships from India it looks like and I cannot really find much information on it on the web. The thing that I am interested in is the fact that it actually comes with a new Fuel Mixture screw!

Not familiar with that kit.
But the 75-80 2F kit by Keyster does include the same desmogged mixture screw.
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
Was looking at the screw this weekend and realized that I had forgotten how jacked up my old fuel mix screw was. Seems to seat and seal properly but the end was apparently broken off and then cut by the PO to be able to adjust it.

@FJ40Jim could this possibly create an issue where the high idle comes into play? Say like a small vacuum leak that is constant?
 

NeverGiveUpYota

Dare me.
SILVER Star
Joined
Mar 28, 2011
Messages
7,018
Location
East Hampton, CT
Was looking at the screw this weekend and realized that I had forgotten how jacked up my old fuel mix screw was. Seems to seat and seal properly but the end was apparently broken off and then cut by the PO to be able to adjust it.

@FJ40Jim could this possibly create an issue where the high idle comes into play? Say like a small vacuum leak that is constant?
Let’s see this jacked up IM screw.
 

FJ40Jim

The Cruiser Whisperer
SILVER Star
Joined
Sep 26, 2003
Messages
11,108
Location
Lancaster, Ohio, USA
No, the high idle can only come about because something is keeping one of throttle blades from closing fully. An engine needs air to run.

The mixture screw could make it idle lean & stumbly, or slobbery rich & stumbly.
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
Thanks Jim, I just wanted to check and make sure.
@NeverGiveUpYota F - I will see if I can grab a pic of it tonight. You know, priorities and all, the bike is calling me and we have actually had a couple of semi-clear days without smoke from #$%ing Commifornia being on fire yet again so I gotta get in my pedal time so I don't throat punch people. :cautious: :eek::flipoff2:
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
Hi @gregnash , I just discovered your post and it looks like we are having the exact same symptoms, see my thread: 3F Carb intermittent high idle

Thanks for tagging me. Yeah I am still fighting my issue and almost exactly the same are yours. Definitely something to do with my particular carb however main difference is that I have personally rebuilt mine twice and it happened AFTER the rebuild. So either the rebuild knocked something loose that is now rattling around in there OR there is a discrepancy in parts with my carb (for whatever reason).

I am partially wondering since I originally dipped my carb in CARB-DIP when I first rebuilt it, that it was either not full clean after I took it out, thus gumming up one of the butterflies or my butterfly bushings are just shot now (god knows how well the POs took care of the carb) and thus the butterflies are messed up.
 
Joined
Oct 22, 2015
Messages
32
Location
Brisbane
Not sure how or exactly when mine started to play up. It's a weird problem and because the carb is all mechanical, there has to be some sort of logical explanation ...
Have you ever been able to open it up and watch the butterfly valves while running with the problem?
 
Joined
Jun 21, 2018
Messages
88
Location
Montana
Sorry, don't mean to hijack. How do people go about contacting Jim about sending a carb for rebuild? Anyone know price and lead time? Thanks!
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
Best is either email or call. He is a busy man in a one man shop so can take him a bit to get back to you... Carb rebuild is $400, I am currently waiting on mine to be sent back.
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
So something that I randomly thought about yesterday was @mwebfj60 post on the secondary system for the carb. This got me thinking about my high idle issue and the fact that my secondary slow cut valve on my OEM stock carb has always had a slight leak.

After the last rebuild I did the mod where I put the white holley lighter spring in the secondary diaphragm to allow the secondary to open easier. However, I am wondering if for whatever reason my secondary slow cut system is now completely open to vacuum which is causing the system to constantly draw fuel in through the secondary system, thus creating the high idle. The momentary blip of the gas pedal would cause a drop in the vacuum that could potentially get the leak in the secondary system to then go away which allows me to go back to a "normal" idle that I have set.

@mwebfj60 @OSS @Spike Strip @FJ40Jim @CaptClose What do you guys think? Does my thought process make sense?
 
Joined
Sep 17, 2010
Messages
1,740
Location
Central Valley, CA
So something that I randomly thought about yesterday was @mwebfj60 post on the secondary system for the carb. This got me thinking about my high idle issue and the fact that my secondary slow cut valve on my OEM stock carb has always had a slight leak.

After the last rebuild I did the mod where I put the white holley lighter spring in the secondary diaphragm to allow the secondary to open easier. However, I am wondering if for whatever reason my secondary slow cut system is now completely open to vacuum which is causing the system to constantly draw fuel in through the secondary system, thus creating the high idle. The momentary blip of the gas pedal would cause a drop in the vacuum that could potentially get the leak in the secondary system to then go away which allows me to go back to a "normal" idle that I have set.

@mwebfj60 @OSS @Spike Strip @FJ40Jim @CaptClose What do you guys think? Does my thought process make sense?
That's some nice out of the box thinking. I've mulled this around since you tagged me and the blip of the throttle is what I keep coming back to. To me it seems either mechanical or vacuum related. Like Jim mentioned above, could be a butterfly hanging up and staying open just a little. There is fore to aft movement on the shaft the butterfly valves are screwed to and really what keeps them centered in the bore is the butterfly itself. Can you see any marring or anything on the bore where maybe one is hanging up? When the high idle is happening maybe try moving the butterfly shaft fore or aft by hand and see if it drops the idle. If you just sit and let it idle high does it eventually settle back down by itself?

On the secondary side, the butterfly valves would have to be partially open as well to draw enough vacuum to pull gas through the slow cut valve and if it is just a leak, it doesn't seem like there would be enough fuel supplied with the air to bump your idle up unless that valve is totally shot and fuel flows freely. Maybe an issue with the secondary diaphragm not returning back down after it is engaged, that would cause the secondary butterflies to stay open a little. This still wouldn't account for enough fuel through the slow cut valve though. Have you tried manually pushing the diaphragm rod back down by hand when the high idle is happening? Maybe pop the slow cut valve off and check how much flow it has when closed with some low pressure compressed air?

Then the power valve keeps popping in my head. Could be a power valve sticking open and letting excess fuel flow but then again, you need the airflow. This one is kind of counterintuitive because the power valve opens under low vacuum like WOT. A couple of my carbs had very sticky power pistons that had to be "honed' a bit to get them to slide in the bore smoothly.

Then vacuum comes to mind as it's when the motor is warmed up and various vacuum scenarios change with the HIC and BVSVs. But your issue only happens with your carb so that pretty much rules those things out.

The only way I see extra fuel causing an increase in idle without the excess airflow through the butterflies is if you are running lean at idle or you have a vacuum leak. If you're running lean at idle, it would seem backing out the IM screw would give you increases in RPM and I'm sure you've been through the lean drop a few times and would have found that by now. Or...a different scenario, if you are running overly rich and after driving, the fuel level in the bowl is dropping and causing the mix to lean out and increasing the idle, then with the little shot of fuel from the pump, richens it back up and drops it down...again, you probably would have caught this on the lean drop and sometimes bumping the throttle works and sometimes it doesn't.

A test for test's sake may be to pull the vacuum line off the choke opener, back the high idle screw out, then see what happens when pulling the choke cable when it's doing it. Just to see what happens.

That's all I got bud. Wish you were closer, this is the type of tinkering I enjoy...as frustrating as it is, still fun for me.
 

morganism

SunkCostFallacy
Joined
Jan 17, 2009
Messages
806
Location
Verde Valley, AZ
Isn't there a regular fail mode on the VTV under the intake manifold on this engine?

I think there is an exposed wire harness out front, you can back probe for failure. two yellow wires. I think the post was " removing the VTV without pulling manifold" or something like that?
 

FJ40Jim

The Cruiser Whisperer
SILVER Star
Joined
Sep 26, 2003
Messages
11,108
Location
Lancaster, Ohio, USA
Your thought process is remarakably convoluted. Congratulations!

The only way to have a high idle is for something to be allowing more air & fuel into the engine. A bad PCV valve or brake booster could allow more air into engine, but with no additional fuel, the idle would be lean & stumbly.

An oversize idle jet could allow too much fuel into engine, but that would result in a loaded up, rich idle.

To get a higher idle, one of the throttle blades in the carb is not fully returning to its' hard stop. A slightly open throttle is allowing in more air, which is drawing in more fuel, feeding the engine more combustible mixture which results in more speed. Since the SSCV should prevent fuel flow in the secondary barrel, the slightly open throttle is probably the primary.
 

gregnash

Anal Retentive Analyst
SILVER Star
Joined
Nov 3, 2011
Messages
12,195
Location
Carson City, NV
Your thought process is remarakably convoluted. Congratulations!

The only way to have a high idle is for something to be allowing more air & fuel into the engine. A bad PCV valve or brake booster could allow more air into engine, but with no additional fuel, the idle would be lean & stumbly.

An oversize idle jet could allow too much fuel into engine, but that would result in a loaded up, rich idle.

To get a higher idle, one of the throttle blades in the carb is not fully returning to its' hard stop. A slightly open throttle is allowing in more air, which is drawing in more fuel, feeding the engine more combustible mixture which results in more speed. Since the SSCV should prevent fuel flow in the secondary barrel, the slightly open throttle is probably the primary.


LOL thanks Jim, I think?! Just my overly analytical mind trying to figure things out. That is why we rely on you guys, the true experts, to shut it and go sit in the corner and continue playing with our lincoln logs!!
 

Users who are viewing this thread

Top Bottom