Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

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candymancan
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Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

Im trying to adjust the idle on my Jeep and i know there is a anti diesel solenoid on the carb of my 90 which automatically sets idle. And you can adjust that by turning the bolt on the solenoids bracket. Im pretty sure though you have to disconnect the solenoids power so the nipple isnt sticking out pushing the throttle lever. and then put the Jeep in neutral and then adjust the idle on the small adjust screw with a flat tip screwdriver.

Its suppose to be set to 500rpm i believe. Eveb says it on the sticker. But i cant get the actual throttle lever to move back anymore. I can see the screw actually seperating itself from the throttle lever. I figured maybe the throttle itself is stuck so i wd40 it and the springs, and if i manually try to push it back it still wont move. Its tapped out it seems.

Checking the idle with a tach its at 650rpm in neutral. 150 over what im trying to get it too. And i cant go any lower because the throttle lever wont move back anymore.

Sooo what do i do ?
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)
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tgreese
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by tgreese »

Possible you have a vacuum leak. The choke side also has a fast idle adjustment screw that should clear the fast idle cam at operating temperature, but may be adjusted badly. You also have an idle stop screw on the carburetor body (throttle side), as well as the fast idle solenoid.

Are you sure it's anti-dieseling and not faster idle with air conditioning? Those solenoids can be present for either purpose. I tht case, the idle stop on the carb body would control the "normal" idle and the solenoid would boost the idle when the compressor is pumping.

You should be able to close the flaps enough to stall the engine. If none of the above are blocking, and you have no vacuum leak, then suspect that the throttle flaps are misaligned in the carb bore and not allowing a tight seal when closed.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
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Topic author
candymancan
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

Well when i plugged the anti diesel solenoid back in. The plunger didn Move back out. When prior it would be sticking out.. now its limp.

Pretty sure it has nothing to do with the a.c. i dunno how to check that though as my comoressor is siezed and i dont wanna turn that on to see.. but when the a.c worked i never noticed idle going up. It in fact would go down and i always jad to adjust idle in the summer for 100rpm more to compensate
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)
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tgreese
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by tgreese »

Non sequitur much?
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

sirrus
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by sirrus »

It is pure anti-dieseling thing, at least in later years - solenoid is powered from the same wire as carb bowl vent solenoid and choke heater. There isn’t anything connecting it to AC system
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

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Topic author
candymancan
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

tgreese wrote: Fri Mar 19, 2021 1:22 pm Non sequitur much?


Dude just stfu.
Last edited by candymancan on Fri Mar 19, 2021 5:23 pm, edited 1 time in total.
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

Topic author
candymancan
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

sirrus wrote: Fri Mar 19, 2021 2:48 pm It is pure anti-dieseling thing, at least in later years - solenoid is powered from the same wire as carb bowl vent solenoid and choke heater. There isn’t anything connecting it to AC system
Thats why i said it was a anti diesel solenoid. But tgrease seems to know all. I already know the proper way to change the idle on these carbs. Its done by the solenoids bolt thats attached to a spring. Not by the (idle) screw on the throttle lever.

But i was having issues with that.. If anything tgrease was non sequturing by suggesting it was the a.c solenoid and had no corelation with the idle.

I fixed it so its fine. Thanks
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

will e
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by will e »

It's a common misconception that this was used to increase the idle when the AC is on.

I've noticed that mine isn't strong enough to push hard enough to increase the idle. It pops out when the throttle is opened and then keeps the throttle at a slightly higher RPM. I believe it is one of the reasons the owners manual has you turn the key to 'on', press/release the gas, and then start the engine. This allows the idle arm to pop out.
81 Waggy 'WILL E' Retired
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1978J10REDWHITE
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by 1978J10REDWHITE »

Is there a temp switch on the intake manifold that causes it to send 12v to the solenoid?
Possible it it failed, or the wiring somewhere broke - disconnected.
Always verify fuses in the circuit..

Get a DVM, verify the solenoids resistance internally, these can open and fail too.
I am not sure what it would be, yet I would guess about 20-30 OHMS on these small wires in them.

Being you truck at its age I would look over ALL the hoses and lines that have anything to do with vacuum, even the larger ones that are maybe 3/8 or 7/16 like PVC -EGR ones.

Verify you do not have vacuum leaks on these old small hoses someplace like in the TC box or at the firewall.

There may be a schematic or TSM online https://oljeep.com/edge_parts_man.html

Topic author
candymancan
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Joined: Tue Mar 22, 2016 11:32 pm

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

The vacuum lines were all replsced a few years ago. I also removed all the factory emission stuff. And the factory air hat with its mess of vacuum lines. Some CTOs are plugged now and i only have thr basic stuff running. There is no vacuum leak. The issue was the auto choke was stuck. Not fully but if i pushed on it, it would pop down fully and open properly. Wd40 and massaging it back and forth freed it up. Now it releases when its suppose too.

The solenoid though is still not engaging anymore though. Which is weird as it was engaged before i disconnected it to set the neutral idle. It wont renegage though.

Aparently i dug up its connected to the ignition switch. When you turn the key to power its suppose to engage. Im going to apply 12v from the battery to see if it engages or not to rule it out as being bad. If it works then i gatta find out why its not getting power and do some wire tracing probably
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

marc
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by marc »

Do you have the original air cleaner setup and does it have "vacuum motors" on the various trap doors like my 84 j10. Two major vacuum leaks turned out to be the vacuum choke pull off and the vacuum motor on the door in the air cleaner that diverts air flow to come from the manifold stove. The former I replaced and the latter I removed, pried apart and fixed the diaphragm with thin bike tire repair tape, a narrow strip around each side of he fold. Put it back together and peanned and compressed the rim back in place. When I got the truck it was idling at 1200 rpm, dieseling often.

The other odd thing was that the idle often would not go back to 600 rpm, it would go to 700 or 800. You could easily push the throttle back to the normal idle. I believe the throttle return springs were so loose that it was too easy for friction to catch the throttle. Put on a heavier spring on and that helps.
J10 1984, very stock with AMC 258.
Truck appears to have been rebuilt or restored at one time

letank
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by letank »

there is an extra adjusting screw behind and below the throttle cable assembly, that could prevent the throttle from fully closing.

the idle solenoid is usually not strong enough to increase the idle speed as per TSM, you need to push the throttle a bit for the idle solenoid to step up the idle speed
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)

marc
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Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by marc »

Michael, now you have me wondering if the stronger throttle return spring might be working against the solenoid and could it be contributing to the difficulty starting the j10. Takes four cranks to start, when I got it, it started right up but it was idling very fast, leaking vacuum as well as oil and the timing was way out. Easy enough to put the old spring back in and see if it makes a difference.
J10 1984, very stock with AMC 258.
Truck appears to have been rebuilt or restored at one time

letank
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Location: SF bay area

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by letank »

marc wrote: Wed Apr 07, 2021 9:50 am Michael, now you have me wondering if the stronger throttle return spring might be working against the solenoid and could it be contributing to the difficulty starting the j10. Takes four cranks to start, when I got it, it started right up but it was idling very fast, leaking vacuum as well as oil and the timing was way out. Easy enough to put the old spring back in and see if it makes a difference.
this can happen, also the choke mechanism on the other side can be binding if there is not enough clearance or if the fast idle cam get stuck as one of the lever is plastic and can break... as we are talking about the motorcraft 21xx series carburetor.

In doubt, you can keep the hood up and do a visual inspection of the clearance of the throttle lever.

If the charcoal canister rubber diaphragm starts to leak it allows more air to bleed into the PCV circuit, and result in a higher idle... the diaphragm is under the larger cap of the charcoal canister , the cap that has printed " do not open" because there is a large spring under the diaphragm!
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)

marc
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Joined: Tue Aug 11, 2020 8:24 am

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by marc »

My J10 has the straight six with the notorious BBD carb. It did have problems with the choke hanging up but I believe I have resolved them. Now, I suspect that something else is in the way, maybe the carb is not holding a charge of gas or a weak fuel pump. But, I do need to go back and reset the idle jets and check the timing to be sure that neither of those are the issue. Put the old, weak throttle return spring back in and it did not change the starting issue. Once the vehicle is running, starting is not a problem.
I also was wondering about the plastic cam that the idle screw rides on, anybody have problems with that wearing out?
J10 1984, very stock with AMC 258.
Truck appears to have been rebuilt or restored at one time

Topic author
candymancan
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Joined: Tue Mar 22, 2016 11:32 pm

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by candymancan »

marc wrote: Mon Apr 05, 2021 3:58 pm Do you have the original air cleaner setup and does it have "vacuum motors" on the various trap doors like my 84 j10. Two major vacuum leaks turned out to be the vacuum choke pull off and the vacuum motor on the door in the air cleaner that diverts air flow to come from the manifold stove. The former I replaced and the latter I removed, pried apart and fixed the diaphragm with thin bike tire repair tape, a narrow strip around each side of he fold. Put it back together and peanned and compressed the rim back in place. When I got the truck it was idling at 1200 rpm, dieseling often.

The other odd thing was that the idle often would not go back to 600 rpm, it would go to 700 or 800. You could easily push the throttle back to the normal idle. I believe the throttle return springs were so loose that it was too easy for friction to catch the throttle. Put on a heavier spring on and that helps.


This i habe noticed. I can tap the gas pedal when its all warmed up.. and idle will be at say oh i dunno lets say 600rpm. Then when drive and let go of the pedal slowely and then come to a stop. Idle will be at 700 or 750rpm.. then if i tap the throttle quickly itll go back to 600.

Its like its getting stuck or something
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

letank
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Joined: Wed Oct 03, 2012 9:16 pm
Location: SF bay area

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by letank »

candymancan wrote: Fri Apr 09, 2021 11:07 am This i habe noticed. I can tap the gas pedal when its all warmed up.. and idle will be at say oh i dunno lets say 600rpm. Then when drive and let go of the pedal slowely and then come to a stop. Idle will be at 700 or 750rpm.. then if i tap the throttle quickly itll go back to 600.

Its like its getting stuck or something
We have carb... and the idle can indeed varies greatly upon temperature, humidity... My motorcycle with 3 carbs has the same issues, specs is 1200, but can go to 1400 or barely 1000... I am only concerned if it stalls...

Marc with the BBD, you should start your own thread for better coverage and better answers
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)

letank
Posts: 4009
Joined: Wed Oct 03, 2012 9:16 pm
Location: SF bay area

Re: Cant adjust the neutral idle to 500rpm the throttle lever wont go back anymore

Post by letank »

check the clearance that I mentioned earlier :

Image
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)
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