Carb trouble

[76classic]

Hi Gang, I'm new here and could really use your help. Purchased an untouched 1976 fj40. Only work done by po was holly carb installed and new header. Po gave me original Aisin carb which I had rebuilt and installed. All vacuum hoses hooked up correctly. This is the thing. Only runs with choke engaged. Idle actuator has 10.2 volts and clicks when ignition is turned on. Have 6.3 volts at other electrical connection in front. By the way, truck ran well with holly except for accelerator pump issue. Any help would be appreciated.

 

[antFJ]

10.2 volts is wayyy low at the idle solenoid. What is the voltage at the battery vehicle running and not running?

running should be more like 14.0 volts... car off the battery should be closer to 12.7 volts.

Let's see some pictures of your setup.

 

[Pin_Head]

The low voltage suggests that there is a bad/corroded wire connection somewhere between the point you are measuring and the battery. Check the fusible link and shine up any connections at the battery and fuse block.

If it idled well with the Holley, then chances are there is no vacuum leak and the problem is a lack of idle fuel either due to the idle fuel cut off solenoid not working or some blockage or obstruction of the idle fuel circuit.

 

[76classic]

Car off voltage at battery is 12.3 volts. Didn't test the selenoid when running. I also have 10.2 volts at the headlights when engine not running.
The set up under the hood is bone stock except desmogged. I will send pics when I can.

 

[76classic]

Also, not sure what the other electrical connection is at front of carburetor, but that has 6 volts when engine not running with ignition on.

 

[76classic]

The low voltage suggests that there is a bad/corroded wire connection somewhere between the point you are measuring and the battery. Check the fusible link and shine up any connections at the battery and fuse block.

If it idled well with the Holley, then chances are there is no vacuum leak and the problem is a lack of idle fuel either due to the idle fuel cut off solenoid not working or some blockage or obstruction of the idle fuel circuit.

The solenoid clicks when ignition turned on and guy who rebuilt it said it was ok. Not sure what the idle fuel circuit is.

 

[Pin_Head]

Clicking means the solenoid part works; not necessarily the valve part.
Idle circuit is all the tiny holes in the carb casting that the idle fuel flows in.

Adjust the idle speed screw until it will just barely idle and then disconnect the idle fuel solenoid. If it stalls, it is getting some idle fuel and you may have a manifold vacuum leak.

 

[76classic]

10.2 volts is wayyy low at the idle solenoid. What is the voltage at the battery vehicle running and not running?

running should be more like 14.0 volts... car off the battery should be closer to 12.7 volts.

Let's see some pictures of your setup.

Can I jump directly from battery to solenoid to test it without frying it?
I'll send post some pics on Monday.

 

[antFJ]

yes

edit: if 10 volts is going to everythign else (coil etc.) then you need to figure that out first imo. try what pinhead said above in regards to the wiring.

 

[76classic]

Here's a couple pics of the carb set up.

 

[Pin_Head]

It looks shiny and "normal", except that looking at it doesn't tell you much. It is not good to have unconnected wires dangling or disconnected and capped vacuum lines if you con't know what they do.
For example, in the stock situation, the power valve is operated electronically by the VSV and if you are missing an electrical or vacuum connection it might be on all the time producing a rich mixture and bad fuel economy.

 

[76classic]

It looks shiny and "normal", except that looking at it doesn't tell you much. It is not good to have unconnected wires dangling or disconnected and capped vacuum lines if you con't know what they do.
For example, in the stock situation, the power valve is operated electronically by the VSV and if you are missing an electrical or vacuum connection it might be on all the time producing a rich mixture and bad fuel economy.

Any ideawhat the electrical connection on the front of the card is for. I have 6 volts at that connection.

 

[Pin_Head]

I'm not sure. Maybe the temp sensor for the EGR?

Measuring voltage on an open circuit is not very informative. It might read a voltage and it might not, depending on what part of the circuit is belongs to.

 

[76classic]

OK, Heres the update. Sorry I fell off the map. Own an industrial complex in Massachusetts and the weather got in the way.
Yesterday I was able to get the 40 idling by messing with the 4 screws on the carburetor. 2 relating to idle 2 relating to choke? Also measured voltage at headlights running 13.7. Now, when I hit the accelerator, engine reacts like bad accelerator pump which I know is good from rebuild. Any suggestions?

 

[Pin_Head]

1. Does it stall when you disconnect the idle fuel solenoid?

2. Is there gas dripping from the primary nozzle while it is idling?

 

[76classic]

1. Does it stall when you disconnect the idle fuel solenoid?

2. Is there gas dripping from the primary nozzle while it is idling?

Stalls when disconnect idle fuel solenoid.
Not sure about gas dripping.
Funny thing. If undisconnect vacuum Jose from front of carb, hesitation at acceleration disappears.

 

[76classic]

Sorry about spelling. On my phone. Here's a pic of vac connection I was just referring to.

 

[Pin_Head]

You are getting idle fuel but it still stumbles off idle even though the accelerator pump is working, correct?

Fuel dripping from the nozzle on to the primary butterfly would confirm that it is not getting enough fuel. The fact that it runs better when you disconnect the power valve vacuum line confirms lack of fuel because this richens the mixture by opening the poser valve.

Sounds like a vacuum leak.

It may be a bad idea to ground that white wire if you don't know what it does.
It is only a ground if it is white with a black stripe.

 

[76classic]

Ok. Removed the white wire. Thanks for that. Sent a pic. Is this the area where fuel should be dripping? There is fuel coming out if that orifice.

 

[Pin_Head]

Yes. The smaller brass tube inside the double ring. That is the primary main nozzle.

Fuel dripping out here is because you had to bump up the idle speed screw to open the throttle plate because it isn't getting enough fuel, probably due to a vacuum leak because the idle fuel circuit is providing some fuel.