Carb decision - Rochester, Aisin, or Weber (1 Viewer)

[FJ55partsBoise]

Dave- Thanks for your posts. Really thanks a ton.

I must be slow as I can't see a way for them to fit? I think I might have a local professional hook this Aisin up. It can't be too much for a mechanic to set this up. I know this is taboo.

Once it is hooked up I know I can do a carb rebuild but getting the linkages setup is the hard part for me.

 

[denis]

the 2F linkage should work with the F carb, the throttle levers and bolt pattern on the carb are almost exactly the same, though the 2F carb may be a hair higher. make sure the linkage you get matches your firewall, you may have issues with the brake booster, brake lines and the factory holes on the tub.

 

[Poser]

Making sure the float really floats and does not sink seems to be a common mistake when rebuilding a carb.

 

[FJ55partsBoise]

Steve-

"Making sure the float really floats and does not sink seems to be a common mistake when rebuilding a carb."

what do you mean by make sure the carb really floats? I replaced the little brass nipple that pulls the float down when I rebuilt it. Can you please explain what you mean? I am ordering a new float from NAPA today.

Thanks

Aaron

 

[Poser]

[quote author=FJ55partsBoise link=board=1;threadid=11186;start=msg101917#msg101917 date=1076342987]
Steve-

"Making sure the float really floats and does not sink seems to be a common mistake when rebuilding a carb."

what do you mean by make sure the carb really floats? I replaced the little brass nipple that pulls the float down when I rebuilt it. Can you please explain what you mean? I am ordering a new float from NAPA today.

Thanks

Aaron
[/quote]

The float, not the carb. The float must float in order to control the fuel level in the carb, you replaced the flow needle. I set them in a bowl of fuel with something on them holding them submerged, to see if there are any air bubbles, or if they fill up with fuel. If the float does not float, it will not shut the fuel flow off to the carb bowl, which will result in a severly rich running condition.

 

[FJ55partsBoise]

Previous posts here addressed this long standing trouble I am having with my FJ40. This thing is really getting annoying. I never thought I'd say this but I am wondering if this truck will always be such a PITA. If so I am tempted to ditch it for a solid axle 4 runner, diesel 60 series or something less trouble. Excuse the venting but this is my only outlet for venting. A week ago OK I ditched the 2 barrel rochester with it's troubles and put a used Aisin on my 1974 FJ40. Aisin is not yet rebuilt but was running on a truck from a good friend.

Background I am running a 2F, front disk, 4 speed, mini truck PS,and header. I was able to find all of the original brackets and make the Aisin work just like the photo's show in Specter offroad catalogue. I hooked it up today and replaced all spark plugs as they were fouled from previous carb trouble.

Today the truck runs very poorly with very high idle, some backfiring, on accleration a bit of fire out the top of carb, and very poor power at low RPMS. When gas pedal is pressed engine response could best be described as spongy and weak. Low end there seems to be a real lack of power. Engine does not rock or shake about under power but power up clean without heavy vibration. I am also concerned with idle speed as the throttle linkage appears to be in correct position for idle yet carb runs to about 4000 RPMS on start up, (seems really high). Is there a idle adjustment screw that is hidden?

Once the FJ40 was warm it would not hold an idle at all. I am wondering if it wasn't the carb after all. This won't be bad as I hated the Rochester very much. I have not touched the timing and don't own a timing gun.

I hate to say this but after a few more tries I am planning on towing it to a reputable shop for a full tune and possibly a carb rebuild.

Any suggestion would be very much appreciated. We are moving and this truck needs to be driveable to get on the back of the semi.

 

[IDave]

Yes, you need to look at the timing.

 

[IDave]

Or, I'll take the truck off your hands for $1000!

 

[Poser]

When you have it running, have you sprayed any carb cleaner at the base of the carb, where it mounts to the manifold, or, possibly, where the manifold meets the head?

Idle solenoid on the carb click?

If the RPM's change when you spray Gummout or other brand of carb cleaner, this means you have a vaccume leak.

Does your linkage to the carb bind up anyplace?

If you unhook the linkage does the idle drop? Is there any possiblity that something is preventing the carb linkage from traveling in the full range of motion, meaning not returning to low idle?

Do you have a tachometer that is telling you that your truck is running at 4000RPM's at startup?


Most people that own anything mechanical, and work on it, have been frustrated.
If it is not this vehicle, it will be another, that makes you pull your hair out.

Good luck!

-Steve

 

[FJ55partsBoise]

Dave- thanks for the tip. I think I will call a mechanic as I don't have a timing gun.

One other problem, I added mini truck PS. The pump makes noise when I turn the wheel? and there are lot's of bubbles in the pump. Is this normal when PS is added to have this happen? I think this trouble is compounded by the poor running situation.

Anyone have the factory specs for the idle settings for a Aisin carb?

 

[FJ55partsBoise]

Steve- thanks.

When you have it running, have you sprayed any carb cleaner at the base of the carb, where it mounts to the manifold, or, possibly, where the manifold meets the head?

I will try this in the A.M.

Idle solenoid on the carb click?

I will try in the A.M.

If the RPM's change when you spray Gummout or other brand of carb cleaner, this means you have a vaccume leak. OK thanks

Does your linkage to the carb bind up anyplace? It doesn't seem to.

If you unhook the linkage does the idle drop? Is there any possiblity that something is preventing the carb linkage from traveling in the full range of motion, meaning not returning to low idle? I can't tell to be honest. I have been messing with this for a long time. It took me a couple hours to get the throw setup so that is was full.

Do you have a tachometer that is telling you that your truck is running at 4000RPM's at startup? No, it just seems very high.



-Steve

 

[Poser]

You have a lean condition that is causing your truck to 'pop' back through the carb....

From either a vaccume leak somewhere near, or past the base of the carb...

Or, from too small of a primary jet in the carb...


Why was this carb that you are trying to install, removed from the engine that it was on, and apparently working?


Just more ?? ?? ?? ??

 

[Poser]

If you unhook the link that attaches to the carb linkage, does it make the carb butterfly rotate any further towards the closed position?

 

[IDave]

Fast idle speed is about 1800 spec, but I find 1500 is about right.
Idle speed is 650 (USA) 500 (NonUSA).
Initial idle mixture is 1 1/4 turns out from fully closed (clockwise to seat, then back out 1 1/4 turns).

 

[IDave]

By the way, the idle speed screw is sort of hidden. It is beneath the fast idle screw on the firewall side of the carb.

I agree with Steve that backfiring could be a lean mixture or intake leak. It could also be bad plugs, bad wires, bad timing, water in the fuel, valve problems, head gasket problems, bad heatriser (have seen this myself!). First thing to do is get a tach and timing light so you can make sure the basic things like idles speed and timing are right. Then you can look to diagnosing the other stuff (although the intake leak check via carb cleaner is an easy one, too). I would get a vacuum gauge, too. These three tools will save you a lot of trips to the mechanic (who may not like your car, anyway).

 

[Poser]

Being that the carb has been off and on, I am willing to bet that the base gasket did not get replaced...sometimes you can get away with not replacing this, but many times, there are running/drivability issues that stem from vaccume leaks at the base of the carb. I know many people that have wrote off a carb to be junk because of this...

Also,

If you do not have the FACTORY service manuals for your engine and chassis, this would be a VERY GOOD investment. The Toyota manuals will cover diagnostic and trouble shooting all systems with your engine, including fuel metering and ignition specifications.
I agree with Dave. You need to get a timing light, and a vaccume gauge. These tools will prove to be indespensible for proper tuning of your engine.


Good luck!

-Steve

 

[FJ55partsBoise]

Steve/Dave-

This Aisin was on a rusted out FJ55 that was being parted by a good friend. Apparently it did run when he bought the truck. I have the chassis manual and I just spent five hours trying to follow vacuum lines checking for leaky hoses. I also found that the newly changed engine oil smells like gas and is now contaminated.

Theme- I am running out of time with this truck.

Here is the list of things from your suggestions. Thanks guys.

1) replace spark plugs
2) replace base gasket, I am ordering a new base gasket tomorrow. Anyone know where to find one local same day in Boise, ID?
3) check for vacuum leaks with carb cleaner. I know it has vacuum leaks from my inital buyers inspection when I bought it. I have never been able to find the leak(s) and they never affected it running much until now.
4) adjust idle screw / determine throttle issues / unhook the linkage and check for idle drop / check for something preventing the carb linkage from traveling in the full range of motion causing it to not return to low idle / Idle solenoid on the carb click?

Now I am very frustrated. I just got off the phone and was told by a mechanic buddy (who makes house calls) and (who used to work at the Toyota Dealer) that he would not recommend rebuilding the Aisin carb as older Toyota carbs are notoriously awful to adjust and get running right.

He recommends something else (he would not suggest a Weber) but he was very cautious to be involved with rebuilding the Aisin. What the heck? Now am I ever confused?

If I go this route what will the Weber, pedal, and correct distributor cost? I guessed the whole conversion at around $750, ouch. Plus paying someone to install the blasted thing as I am out of time.

 

[IDave]

Aisens are not aweful. As I told you, a lot of people don't like them, but I know a lot of folks who would take them over a Weber any day, Steve excepted. I truely believe it is what they are used to, rather than any intrinsic difficulty. I have no probs with mine, and I am no carb expert. I think it is fun to tinker with.

I also think you will find most or all of your trouble is not the carb, but one of the other things we have listed.

 

[FJ55partsBoise]

Dave- thanks and if this is fun can I fly you to Boise using my frequent flier miles with United AL? Free beer and hotel. Just kidding. I think the stress of another corporate relo is getting to me. I have to be honest that I hate my FJ40 for the first time in years.

I will take your advice and pursue vacuum leaks and the other things. As a last report I will rebuild the carb.

Where would you get the base gasket fast?

 

[Degnol]

Any carb kit will have them, NAPA, CarQuest, AutoZone, etc.
Or you can get some gasket material and make one.
GL
Ed