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22r hesitation while accelerating quickly

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Old 03-14-2017, 07:10 PM   #1
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22r hesitation while accelerating quickly

Just bought a 1985 2wd pickup. It's got a 22r with a Weber.. it's been rather neglected... so I'm doing my best to clean it up and get it to its top performance..

Previous owner didn't know much about it(including the fact it had an aftermarket Weber carb)
he did say the previous owner before him rebuilt the motor. Which I believe is true as the block has been painted blue lol..

Anyways, overall it runs very well.. great power, damn near blows my 87 4Runner 22re with 30k on rebuild outta the water.
the only issue that I'm having is a "hesitation" while really getting on the gas. If I ease into it and slowly accelerate it doesn't skip a beat.. I believe it needs to be rejetted as it has from what I can tell, all stock jets that came with the Weber.. also, when operating the throttle by hand should I be seeing the secondary open up? I never see it open up. And if I manually open the secondary by rotating just the secondary shaft it's hesitates/spits and sputters. It when I run the primary throttle it's runs smooth o matter what I do..

any other ideas on what the issue could be?

but before I dive into the carb I have a few other things I want to sort out. While setting the timing when I unplug and plug vac lines to there is not advance unless I set the idle to 1200+. Is this normal or should the idle always advance when distributed vac lines are unhooked? Could I have a low vacuum issue? Anyone have a good vacuum line diagram? There's a good chance there's some lines that are out of place (seeing as the pig tail for in dash temp gauge was plugged into the electric choke

Also in my fuse block there is a relay plug that looks like someone has jumpered? Any idea which relay is supposed to be there and why it would b bypassed? (Pic attached)

lastly, what are all the switches on the intake manifold? I know one is the indash temp gauge that is now hooked up properly.. then there is 2 different switches that both call for 2 vacuum lines. What are these and are they needed? The one closest to the head has nothing hooked up and the other one is.. and then another pig tail closest to the radiator what is this? Mine is not plugged in nor do I see any wiring for it..


The list goes on and on but I suppose this is a start lol.. these are just the issues I can't figure out by myself. Thanks in advance, any and all input is welcomed..



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Old 03-14-2017, 07:23 PM   #2
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The vacuum and carb hesitation could be the same things. What does the inside of the Weber look like and what jets are in it?
I would change out the fuel filter just to know its status - that is an inexpensive maintenance item.
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Old 03-14-2017, 07:46 PM   #3
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Inside of Weber looks great. Very clean. I popped it open and changed the upper and lower gaskets when I first bought the truck. I Will eventually order a jet kit and rebuild kit but I want to rule out vacuum first. Im not positive I have a vacuum leak and/or vacuum lines out of place.. but I feel there is a good chance. And will do on the fuel filter, good call.

as for the current jets, I'm not positive. I'm going to take it back apart and write them all down hopefully tomorrow and I will let you know. I do know the primary idle jet is 60 and secondary is 50.

Also, any idea if my secondary should be opening up while revving throttle at an idle? I'm new to the whole carb scene.. I know the basics but that's about it.

Last edited by Shagool22; 03-14-2017 at 07:49 PM. Reason: Forgot to add more details
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Old 03-14-2017, 08:23 PM   #4
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Get a number off you accel pump jet and IIRC (its been a while) the Air Correctors and Emulsion tubes.

The tuning is partly dependent on what other equipment you have on the tuck - like headers.

PS check your timing too.
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Old 03-15-2017, 02:59 PM   #5
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If I recall correctly the secondary doesn't start opening until about half throttle so if you're just reving it from idle wilt no load you aren't likely opening the throttle enough. Check again with engine off and just slowly open throttle and watch the butterfly valves operate.

The distributors have both a mechanical and vac advance so if you rev it with the vac lines unhooked it will still advance. If you have a timing light with a delay, you can try running it up with the vac lines attached. I believe you want to se about 28 at 2500 rpm's with everything hooked up and working properly.
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Old 03-15-2017, 07:37 PM   #6
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Bingle good call on operating throttle with truck off, secondary does indeed open up.. thank you for the reply

And yes timing does advance when I rev it.. maybe I was a little unclear but my question there was when you unhook vac lines at distributor idle should go up and timing should advance correct? Should this happen regardless of that I have my idle set at? Example if I have my idle set at 750 and unhook vac lines nothing happens. If I turn in idle screw and idle at 1000 and unhook vac lines the idle will increase and timing will advance as it should.. just wondering if maybe I wasn't pulling enough vacuum at lower rpms but maybe this is how it works?

Anyways, I'm proud to admit I'm an overthinker lol no more hesitation! Was doing some basic tune up procedures and pulled spark plugs.. and one of them was completely the wrong spark plug. different size, gap was too tight, and tip was barely hanging on.. she now puts like a kitten and no hiccups while accelerating.

Now on to figuring out and replacing vac lines.. still think they aren't all in the proper positions. Maybe even a desmog.. and figure out why there's a jumper wire in my fuse block
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Old 03-15-2017, 07:58 PM   #7
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Bingle good call on operating throttle with truck off, secondary does indeed open up.. thank you for the reply

And yes timing does advance when I rev it.. maybe I was a little unclear but my question there was when you unhook vac lines at distributor idle should go up and timing should advance correct? Should this happen regardless of that I have my idle set at? Example if I have my idle set at 750 and unhook vac lines nothing happens. If I turn in idle screw and idle at 1000 and unhook vac lines the idle will increase and timing will advance as it should.. just wondering if maybe I wasn't pulling enough vacuum at lower rpms but maybe this is how it works?

Anyways, I'm proud to admit I'm an overthinker lol no more hesitation! Was doing some basic tune up procedures and pulled spark plugs.. and one of them was completely the wrong spark plug. different size, gap was too tight, and tip was barely hanging on.. she now puts like a kitten and no hiccups while accelerating.

Now on to figuring out and replacing vac lines.. still think they aren't all in the proper positions. Maybe even a desmog.. and figure out why there's a jumper wire in my fuse block
Well their both Champions so there's that.
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Old 03-16-2017, 06:06 AM   #8
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^^ Lol, what he said!
Glad you got that worked out. You never know what some previous owner/idiot did to the truck. I've had mine for the past 20+ years so I'm stuck cursing my younger self for dumb stuff done to my truck.

With the Vac advance, I've only ever had the "single hose" style and I don't know what the second vac line does on the newer one, so you may not be off base in your thinking (I think it may retard the timing in certain situations), but it's called a Vacuum advance for a reason. At idle it doesn't advance the timing much, but as rpm's increase, vac increases, timing advances. Follow? If you held the rpm's at 1500 and then unhooked the vac line your timing would retard significantly(and likely your rpm's would drop as well due to poor timing).

On to the jumper wire. Is your truck a mechanical fuel pump (pass side, near front of head) of an electrical? I was reading somewhere, on efi trucks, that you would do a jumper that looked like that to bypass a faulty fuel pump shut off that would cause it to hard start. It would turn on the elec pump when key was in on position insead of waiting for signal from the MAF saying the engine was running. Don't know it that's what it is or not. Totally a guess. I'd try pulling it then see if everything seems to run and operate fine, if not you have a better start to tracking down what it's doing in there. Maybe post up separate question in electrical portion if we can't get that one answered on this thread.
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Old 03-18-2017, 04:27 PM   #9
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Okay yup I follow.. that all makes sense. This is my first carbureted rig so I'm full of questions..

Anyways, truck is still running flawless after plugs, plug wires, carburator tuning, and setting the timing. I finally got around to checking all my jets on the Weber 32/36. While trying to tune the carb my mixture screw has to be out a minimum of 3.5+ Turns to idle worth a crap. And from my understanding you don't want to be over 2.5? Here's my stats:

(Primary=first number)

Main jets- 140/150
Air corrector jets- 170/180
Idle jets- 60/50
Accelerator pump jet- 50
emulsion tubes- 50/50

Last edited by Shagool22; 03-18-2017 at 04:33 PM.
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Old 03-18-2017, 04:30 PM   #10
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And as for the jumper, I'm scared to mess with it honestly lol.. I have a mech fuel pump.

Edit: just traced wires. Both are black wires with a yellow stripe. But ones big and ones small.. hard to tell where they go but, I noticed the plug that goes into the bottom of intake has the same wire color/size. I unplugged that and got out the multimeter. With the jumper in and key on there is 12v. Disconnect jumper with key on it goes to 0v.

Last edited by Shagool22; 03-18-2017 at 04:57 PM.
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Old 03-18-2017, 04:31 PM   #11
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Read this regarding 32/36 tuning on a 22R - https://www.yotatech.com/f115/weber-carb-info-241818/
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Old 03-18-2017, 07:53 PM   #12
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Thanks L5wolvesf. I have indeed searched a read a ton of those threads on tuning this carb. From my understanding I need a richer primary idle jet..

Upon more research I have also concluded that the jumper wire is for the CMH (cold mixture heater). Seems a previous owner had the relay go out and decided to just bypass the relay with a jumper wire.. which leads me to my next question....

What exactly is the function of the cold mixture heater? Is it necessary?
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Old 03-18-2017, 08:07 PM   #13
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Thanks L5wolvesf. I have indeed searched a read a ton of those threads on tuning this carb. From my understanding I need a richer primary idle jet..

Upon more research I have also concluded that the jumper wire is for the CMH (cold mixture heater). Seems a previous owner had the relay go out and decided to just bypass the relay with a jumper wire.. which leads me to my next question....

What exactly is the function of the cold mixture heater? Is it necessary?
No problem. If your engine is stock try going/starting with the jetting recommended there. But, only make one change at a time. If you change a couple things without trying it out you wont know what worked or didn't. Really the best way to get it jetted right is on a chassis dyno - but the time ain't cheap. Make sure everything is good, valves adjusted, filters are clean, etc before you make significant changes. That way you have a baseline to work off of. Working with different timing settings may yield a bit more too.

Far as the cold mixture heater is concerned, I have to let one of the other guys chime in on that.

P.S. The elevation you live at may have some effect on the best jetitng too.

Last edited by L5wolvesf; 03-18-2017 at 08:11 PM.
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Old 03-18-2017, 11:12 PM   #14
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My 1987 Factory Service Manual says this about the Cold Mixture Heater: "To improve cold engine emission and drivability, the intake manifold riser is heated during cold engine operation to accelerate vaporization of the liquid fuel."

So essentially it tries to bring more of the liquid fuel into a vapor state. If more of the liquid fuel turns to vapor, then you should get a better, more complete burn.

It appears that the relay for the Cold Mixture Heater is (or in your case, was) triggered by the emissions computer.

The emissions computer gets a signal from Temperature Switch 1 which is what switches the heater on and off depending on coolant temperature.

Depending on what was jumpered and what parts of the emissions system is left, your Cold Mixture Heater may be always powered or no longer powered at all (I suspect the ladder but it would be good to check).

I don't have any experience with Weber carburetors, but since many of the emissions systems are removed when converting to a Weber, the CMH probably isn't necessary (and won't work correctly if other components that trigger the CMH are removed).

Hopefully others who have converted to a Weber can share what they did with the CMH.


I am glad you changed out those terrible spark plugs!


Last edited by old87yota; 03-18-2017 at 11:17 PM.
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Old 03-19-2017, 06:33 AM   #15
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So it seems like the CMH does a choke related job. Which leads me to ask - what type of choke does your Weber have - water, electric, manual? And how does it run first thing on a cold AM?
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Old 03-19-2017, 02:35 PM   #16
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My 1987 Factory Service Manual says this about the Cold Mixture Heater: "To improve cold engine emission and drivability, the intake manifold riser is heated during cold engine operation to accelerate vaporization of the liquid fuel."

So essentially it tries to bring more of the liquid fuel into a vapor state. If more of the liquid fuel turns to vapor, then you should get a better, more complete burn.

It appears that the relay for the Cold Mixture Heater is (or in your case, was) triggered by the emissions computer.

The emissions computer gets a signal from Temperature Switch 1 which is what switches the heater on and off depending on coolant temperature.

Depending on what was jumpered and what parts of the emissions system is left, your Cold Mixture Heater may be always powered or no longer powered at all (I suspect the ladder but it would be good to check).

I don't have any experience with Weber carburetors, but since many of the emissions systems are removed when converting to a Weber, the CMH probably isn't necessary (and won't work correctly if other components that trigger the CMH are removed).

Hopefully others who have converted to a Weber can share what they did with the CMH.


I am glad you changed out those terrible spark plugs!

Great info!!
From what I can tell, most of the emissions are still intact. But I've never owned a carbureted 22r so I could be wrong. The only thing I know for sure that is gone is the air injection ports off exhaust manifold are blocked off...

now which one is temp switch 1? The one to the left of thermostat housing or the one on the right?
Also there's a pig tail sensor on the intake towards the front of the head. What is this mine is unplugged...

ill attach some some pics of this mess lol
Yes that is electrical tape lol
Is this temp switch 1?

And this one? Also look below that to the pig tail switch
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Old 03-19-2017, 02:39 PM   #17
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So it seems like the CMH does a choke related job. Which leads me to ask - what type of choke does your Weber have - water, electric, manual? And how does it run first thing on a cold AM?
Electric choke. And runs great on cold cold mornings. No issues tap gas peddle twice before turning key and fires right up no needing to hold gas peddle down at anytime.
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