Rough running 1976/1979 2F, what am I missing? (1 Viewer)

[fabiodaddy]

Hey guys, need some advice here. Sorry for the longish post, just wanted to try and give as much info about the rig as I know.

Purchased a 1976 FJ40 a few months ago. Least rusty one I could find in my budget. Had a bunch of work done on it already (new OME suspension, electronic ignition, new seats/console, new tires etc.), but ran a little rough. Figured it should be easy to sort out so made the purchase. Not a lot of history about the rig other than the little I got from PO. I think it went from stock 76 2F to SBC (sigh) and then to the 79 2F.

First thing to sort out was the cooling which I have fixed (new radiator, WP, hoses etc.)

Next was to tackle the rough running 2F. It's a 1976 but has a newer 2F in it. Best I can tell from serial # (2F343733) is early 1979. It has Toyota power steering.

Came with a Weber and a Electronic Distributor (HEi unit from MAF i believe). First thing I did was order a new carb from Trollhole. Finally got that in and replaced the carburetor. Had to un-weberize the linkage a stuff, but it was all there. Stock parts fortunately in the parts box from PO. THC had a weird spot in the casting and seemed like it was cracked clear through. Not sure if it is, but let Marshall know and he put a new one in the mail.

While waiting, I installed the THC anyway. Still had to fix a bunch of stuff to get the new carb set up so at least I could get all of the lines and linkages sorted out.

Still ran rough with THC on and I noticed it only pulled 5-6 inches of vacuum. Not surprising since it had a bad exhaust leak as well. Crap, time to pull the manifolds and replace gaskets. Ordered a set of Remflex gaskets and a EGR port block plate from Mark. Bolts stripped out at EGR port and leaking badly. I'm guessing that the new gaskets should take care of the exhaust leak as well as the vacuum leak.

Gaskets and EGR plate arrive and I pull the manifolds. Not as bad as I was expecting...no broken bolts or anything. Good.
I can see from carbon buildup that exhaust manifold was leaking as well as EGR port. Manifolds look to be in good shape with no cracks. Should be an easy fix me thinks.
Get manifolds back on, Remflex seems to snug up really well. I decide to torque to 30 lbs which is right between Remflex recommendations and stock torque. I also got the new carb from Marshall and put that on as well. Fixed broken bolt on EGR port and installed plate and gasket. Things are looking good! Pulled the EGR cooler and associated lines as well. Much tidier now!

Go to start up the rig and it's hard starting. I crank until I see gas in the sight window and pump it a few times and it finally fires, but runs really badly. Worse than before. My exhaust leak seems fixed but I still only pull 5 inches of vacuum???? Will barely run. So I pull the new THC off and put the original THC one back on. It runs much better, but still only have 5 inches of vacuum. I can get it to idle, although it is rough, and I can drive it...but lacks power.
I've plugged up every vacuum port that I can find after the half assed desmog, but I must have missed something?
I also notice that there is raw fuel in the intake manifold. I noticed some when I pulled the carb off before, but also noticed it leak out when I pulled the vacuum meter off of the port on carb base plate.

I have timing ballparked close to 7 degrees, but since it doesn't idle to well I figured I would dial that in after fixing vacuum leak.

As I mentioned above it has electronic ignition with mechanical advance.

Any ideas where I could have missed a vacuum port? I have replaced all vacuum lines. I only have two really. PVC to intake and brake booster to intake. All ports on carb are plugged. I have the EGR line that used to go to EGR cooler plugged off.

Haven't re-torqued the manifold bolts, but at only 5 inches seems like it is something else. Thoughts?
I will post up a few pictures of the setup to see if that helps identify anything.

 

[65swb45]

1. Cap off the PCV and the booster at the manifold and retest.

2. Do a compression test, a valve adjustment, and a second compression test.

One or the other or both should net you some solid info, if not an outright solution.

Best

Mark

 

[fabiodaddy]

Ok. I have an update to the rough running 2F.

1. Capping off the PCV and brake booster made no difference to the vacuum.

Followed Mark's advice and did a compression check and valve adjustment.
2. Compression check. Did two tests per cylinder and averaged the values.

Before After
1. 115 122.5
2. 115 115
3. 120 122
4. 120 125
5. 115 117
6. 120 120

All but 2 and 6 came up, and those two stayed the same. The valves all seemed to tight.

After buttoning everything up I put the plugs back and in and started it up. Hey it runs much smoother and vacuum came up to 12-13.
Then I noticed that the PCV vacuum line was still disconnected. So I capped that off and it almost dies and the vacuum drops back down to 5???
The PCV vacuum line goes right into the carb base plate along with the line that used to go to the EGR cooler. I removed all of the EGR stuff and capped it off at the exhaust manifold and capped off the EGR line at the carb base as well.
So with the PCV disconnected that should be a major vacuum leak? NO?? Yet the vacuum goes up and it runs much smoother, although it idles much higher.

I'm at a bit of a loss.
Anyone have an answer for that?
EGR stuff needed still? I still have it all, but it had such a bad exhaust leak there I just pulled it off.

 

[Solace in Solitude]

Check the PVC and the line that runs from the PVC to the carb base plate... Are either plugged?

Did you reconnect the booster before the vacuum dropped again? If so, start it up, get it to idle. Push the brake pedal down and see if the vacuum drops... Could be a bad booster diaphragm.

 

[honk]

I'm not clear on where your PVC line runs from and to, or whether you have a PCV valve anywhere. I see the aftermarket filter and presume it's attached to the valve cover outlet usually connected to the air cleaner housing?

"PVC" means positive crankcase ventilation. It usually involves a tube with a valve attached at the engine side cover or a valve cover and going directly into the intake manifold through one of the hose attachments - usually just behind the carb for 2F engines. ( think it's only the early F engines that use a tube out of the carb base phrenolic block for PVC suction?) The valve is vacuum controlled and if stuck or sticky could bring your symptoms.

After buttoning everything up I put the plugs back and in and started it up. Hey it runs much smoother and vacuum came up to 12-13.
Then I noticed that the PCV vacuum line was still disconnected. So I capped that off and it almost dies and the vacuum drops back down to 5

Hmm, this seems to say that the engine is getting the air it needs to run well through the PCV hose. With a new carb though ALL needed air should be through the carb and a big added amount as from that open PCV hose should kill it with a loud hiss, not improve it.

Exhaust leaks do not cause vacuum leaks, intake leaks do that. I'm only pointing this out because you've mentioned chasing exhaust leaks but realizing no improvement in vacuum measurements.

 

[JohnnyC]

I'm not clear as well on how it routed ... But... Try this...

Valve cover is on still correct?

Valve cover filler cap is on correct?

Take off that valve cover breather and plug it and see if that changes your vac reading

 

[fabiodaddy]

Sorry about the confusion guys. Let me see if I can clear a few things up.

1. I agree, Exhaust leaks do not generally cause vacuum leaks. But what about when the exhaust leak is in the EGR circuit? From my research here on MUD the consensus seemed to be yes EGR leak does contribute to low vacuum (leak). Maybe I'm wrong.
Anyway I had several exhaust leaks, and a bad one at the EGR port on the manifold. I also had a small exhaust leak at the manifold to head junction. I needed to fix both of those issues so I figured that I probably also had a leak on the intake manifold. So that is where the part about fixing exhaust leaks came into play. And yes none of that helped my low vacuum situation, but did fix most of my exhaust leaks!!!
I removed the EGR system altogether and blocked off the EGR port on the manifold with a block off plate from Jim C. I can put that all back on since I kept it all, and with the new studs and gasket it probably won't leak at manifold now. It was the last part of the smog equipment so I thought I would just pull it off. All the other smog stuff was long gone before I got the rig.

2. PCV routing. As far as I know the PCV line routing is in the 'standard' place for a 79? You can see it in picture number one above. It is the line on the right of the EGR/PCV port on the intake manifold. PCV routes from that line over engine to a port on the side panel. I have replaced that line and cleaned out the PCV valve. It looks fairly new. I thought I eliminated that as a leak when I followed Mark's advice from above (#1). I disconnected and plugged both the PCV line and brake booster and that did not change my vacuum level (still at 5 with both disconnected). I have the EGR port on the intake capped off (rubber cap and clamp also seen in picture 1) while I am troubleshooting the issue.

3. The last time I ran the rig the valve cover was still off since I had just adjusted the valves. So I guess that would eliminate the breather as the culprit?

4. So Honk is exactly right with his comment above. It runs better when it is allowed to pull more air in through the PCV line when it is disconnected from PCV valve. It is normally running very rich as well. You can smell fuel in the exhaust and I noticed all the plugs were black when I had them out to do the compression test.
When I got the rig it had a Weber on it with a clogged up micro air filter. Now I have a THC on it so seems like it should be able to get plenty of air?
The other interesting thing is that when I unplug the PCV valve the engine revs ups and smooths out. But I am unable to get it to idle down with that disconnected.

Hopefully I cleared up a few things.
Thanks for the help I really appreciate it.

And I thought the 40 was gonna be much 'simpler' than my 62. LOL
Fun stuff!!!!

 

[Solace in Solitude]

You don't have the PCV valve upside down do you? It only flows one way.

 

[honk]

There have been a few carbs from Trollhole that turned out to have issues. Usually, as I've understood it, related to machining or assembly debri and easily rectified either by Trollhole or the new owner.

It's hard to imagine any of that causing such a complete airflow blockage but it's often the impossible thing that Murphy brings to bear and is the problem.

Is the choke, whether electric or manual, closed when it should be open?

What might be restricting airflow to the carb?

Have you looked down the bores for anything that might have gotten in there?

 

[Output Shaft]

The EGR system now how you have it is not part of the problem.
So rule that out.

On a "normally" running 2F, if you pulled the PCV hose off the PCV valve, that would create a giant vacuum leak and the engine would sputter at idle, drop RPMs way down and eventually die.

The fact that your engine is sputtering at idle when everything is hooked up, but runs at faster idle and smoother when the PCV hose is open to atmosphere, points to one conclusion: The carb is not supplying enough air to the mixture. The mixture is too rich.

The fact that it smells like that to you only reconfirms it.
So what would cause it to be running so freaking rich?

Stuck choke,
Completely FUBARed jets.
Overall FUBARed carb.

That's all I can think of.

 

[fabiodaddy]

I just redid the intake/exhaust manifold gaskets so had both of those off and inspected. No cracks or anything that I could see.
The rig did the same thing with the Weber on it so that seemed to eliminate the carbs?
Choke is manual with THC and was open.

I had the PCV valve pulled out of line.

Is there something from the smog equipment that is still needed on these smogged 2Fs? The motor is from a 79. Like I said all of the smog equipment has been removed by PO(s). Air pump is just an idler pulley now. The other smog related items like air rail are plugged with allen plugs. Could this be an issue? Did these smogged motors need additional air?

 

[Output Shaft]

The normal sources of air that influence the AFR on all the smog equipped 2Fs at idle are:

PCV
Carb

 

[fabiodaddy]

I have a feeling that this has been an issue with this 40 for a while based on some comments from the PO. I didn't really think about it at the time. I'll go take another look at the intake and carb. I guess both the Weber and TH could be way out of adjustment. Seems doubtful but I don't know what else could be the cause.

Guess it's time to get out the carb adjustment procedures from FSM.

 

[65swb45]

If the carb runs better with an induced vacuum leak, it has too much fuel at idle. Normally that only happens when the idle speed screw is turned in far enough to create a vacuum signal that pulls fuel thru the primary emulsifier.

Try advancing the timing and reducing the idle speed...in that order.

Mark

 

[fabiodaddy]

So I attempted to adjust the carburetor (per FSM) and adjusting the idle mixter screw does nothing. It came from Marshall with 2.5 turns out from bottom. Running it all the way in and out about 5 turns doesn't change anything.
The first carb I got from Marshall had a bad spot in the casting so he sent me another carb. First time I tried the second carb it would barely run and I went back to the first carb. I thought I would give the second one another shot. I put it on and again it barely runs and back fires a lot. I'm guessing it has a separate issue that I'll have to deal with later.

So I'm kind of stuck without having a known good carb, and I have five of them!!!! Almost tempted to rebuild the original Aisin that was in the parts box, but it has a lot of vacuum lines on it.


Mark, I'll try advancing the timing and see what that does. I'll have to put the other carb back on that allows the rig to at least run. I have the idle set down to where it will barely stay running. Not sure what RPM that is since the Tach isn't working. But it seems pretty low and sits there and lopes.

 

[JohnnyC]

I don't think you tried this yet...


Take off that valve cover breather and plug it and see if that changes your vac reading

Keep valve cover on and oil filler on

Check vac and see if it's higher ... Report back

 

[65swb45]

A non-responsive idle mixture screw confirms the primary venturi scenario. It doesn't respond because the motor is getting its fuel from somewhere else. Capiche?

 

[fabiodaddy]

Latest update. JohnnyC. I ran the rig with the valve cover completely off, I had just adjusted the valves, and it still had low vacuum. Is that what your are getting at? If not let me know and I'll try something else. I also had the breather off after I put the valve cover back on at one point as well.

Mark, OK I understand what you are saying now. As I reported earlier I have the second carb from Marshall that I had put on to try. It would not stay idling and would barely run. I fiddled around with that on for a bit and it backfired a bunch and I was going to take it back off and it suddenly started running a little bit better. It would then idle which it wouldn't do before. Maybe a bit of crud in the carb. Not sure.
Any way it will idle now so I tested the idle circuit by disconnecting the idle solenoid and it died. Does that confirm that it's getting fuel from idle circuit and not main?
So with it running, which seems smoother at idle than with other carb on it, I took it for a drive around the block. Still sputters when you try to give it gas and has very little power.
Sigh. Still missing something. I think it ran better with the old crap Weber on it before I started all of this!!!

One other question. I have been measuring vacuum at the carb base connecting to one of the vacuum ports there. You can see the port with a rubber plug on it in the second picture from my original post. That should be fine?

 

[fabiodaddy]

Just an update on this. I have two different THC and each give me different symptoms. One has super rich idle and can not lean it out. Second has better idle, but sputters and no power. Rig runs badly with both. ??????
I still believe I have low vacuum. Might get another gauge to make sure I am indeed getting only 5 inches on idle.

Not sure what to do about remedying that.
Not sure where else vacuum leak can be coming from.
Not sure what my next steps should be.

I have an Aisin carb that I got with the rig. Guessing it is the original from the 79 motor. Looks mostly intact, but I'm sure it needs a rebuild. Hate to have to try and get another carb to work, as I have the THCs, but maybe that is what I need to do. That was my original plan but decided the THC was a much easier route.
Anyway, have to think about that for a bit.
Taking a break from the 40 (I put it in time-out for now) to do some rust repair on the 62. 62 runs great but not a pretty as the 40!

 

[fabiodaddy]

Update.

Finally got back to the 40.

I decided to test the vacuum at PCV port instead at carb base plate. Good news, measurement there is 15 in. I guess that port at base plate is not a proper place to measure. The vacuum still fluctuates when measured there, sometimes dropping down to 12 or even 10 at times, but comes back. Not stable at all.

Not sure what the cause of the fluctuation is. Sticky valve?
I decided to try some Marvel Mystery Oil in it to see if that helps. Never used it before. I guess we'll see.

After that I gave the carb and timing another adjustment. This time the idle setting did have an effect on the idle and I went through and did the lean drop adjustment on it. Adjusted timing with vacuum gauge and it ended up liking an advanced setting the best. Found highest vacuum and then retarded it a bit.

Adjusted the best I could with the stuttering idle. It kinds of lopes! Smooth - rough - smooth - rough. Kind of odd. Anyone have any ideas on that? Sticky valve again?

Anyway now that the thing runs I decided to take it for a drive. Still lacks power. When you go to accelerate it hesitates and takes a while to rev up. I have found that during acceleration if I kind of pump the throttle it is able to rev up faster. Kind of seems like it is leaning out.
Is that a clogged up carb maybe? Weak fuel pump?

I'm still running the new THC I got a few weeks ago. Trying to decide if I want to crack it open and take a look to see if its clogged or just get a rebuild kit for the Aisin and focus on that. Any suggestions there.