78 running rich Carb setup???

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homebuiltcruiser

homebuiltcruiser

10 Year 15 Year
Joined
Jun 22, 2009
Threads
25
Messages
137
Location
Wall Township, NJ
I just got my '78 running, but it's running rough and very rich it seems. Replaced a bad condenser and runs better but still very rich. No emissions are setup on it and it has been rewired with a painless harness so no stock components are in place and i mean none of them! I'm not sure what to do with the two green wires on the carb they have to get wired somewhere I assume (one being the solenoid). Could anyone help me with the best way to hook up the carb to make it run smoothly or would i be better of going aftermarket like the rest of the truck????
 
We also need a better description of what you mean by running "rough", like what it does under what circumstances and why you think it is running rich. Lots of things can make it run rough, but it is not often running rich.
 
getting pics soon

I'll see if I can get some pictures to help out, but I'll try and explain in better detail exactly what's going on. This is the first time I've started the truck in 3 years. I did a complete tune-up and rebuilt the carb with the exception of the secondary diaphragm. I also set the timing. It ran like total **** before i figured out I had a bad condenser. Lots of black smoke (smelled like pure gas). After replacing the condenser it runs better, still some black smoke (gets worse when I rev the engine) and still smells like raw fuel. I have plugged most all of the vacuum lines with the exception of one for the vaccuum advance. I have a line from the large port on the drivers side top of the carb to the large port on the intake directly under the carb. I also put a line from the pcv valve to the port on the top of the intake towards the rear of the truck. Right now I don't have the brake booster tied into anything. The wire on the front of the carb (female end) is not hooked to anything(not sure what its for). and the wire that comes from the rear of the carb(solenoid) I put a jumper wire to the battery to see if that helped it run better.

Hope this helps its hard to write it out without pics
 
did you try leaning the carb out? and sometimes you just need to go take it for a hell ride in the back yard then put it in the garage and see if it runs better. beings it sat for so long. if it was running to lean i wouldn't but in your case i would go for it. like i always say whats the worst that can happen :)
 
It will run rich with the vacuum port with the blue cap blocked off. (The one on the top of the carb, facing front). This is the control port for the "power valve" and it will run rich if there is no vacuum. It needs to see manifold vacuum, so run a line from a manifold source to the power valve fitting.

Also the top wire that goes to the idle fuel solenoid needs to see key on power. The voltage regulator wire (black;yellow stripe) is the nearest place to tap in. Don't use the coil power.

The large carb line on the drivers side is the fuel bowl vent and it goes to the charcoal canister. If you connect it to manifold vacuum it will create a massive vacuum leak and it won't idle.

Just ripping out the emissions and engine control systems is a bad idea if you don't know what everything is supposed to do.
It isn't worth doing anyway.
 
Pin_Head said:
It will run rich with the vacuum port with the blue cap blocked off. (The one on the top of the carb, facing front). This is the control port for the "power valve" and it will run rich if there is no vacuum. It needs to see manifold vacuum, so run a line from a manifold source to the power valve fitting.
Click to expand...

78 should have internal porting for the power piston. However, I have seen a fair amount of power pistons frozen in the 'ON' position. This would make the truck run rich as soon as engine speed was high enough to draw fuel thru the primary.

Just ripping out the emissions and engine control systems is a bad idea if you don't know what everything is supposed to do.
.
Click to expand...

Couldn't agree more.:)

Best

Mark A.
 
I agree strongly about the emissions, especially now that I'm putting it back together. All that was removed when I bought it. I have a box of parts, hopefully there's a charcoal canister in there somewhere! Thanks for the help though guys that'll give me a good start this weekend.
 
In random order:
Remove the 2 screws and flip the Hot Idle Compensator rightside-up. Connect HIC top fitting to the blue capped breather fitting. Connect HIC lower fitting to vac port on carb insulator base. Ignore the 3 small vacuum connections.

Cap off other larger vac fitting in the side of carb insulator base since there is no canister purge hose to connect to it.

Remove & discard Carb Temp Sensor (CTS). There is nothing to hook it to now.

There is the remnant of a manifold Vac (VAC) fitting in the top of the intake just ahead of the carb. It should be capped or removed & plugged.

Show us a pic of the dissy. It should not have a condensor because it is fully electronic. It may be a points dissy w/ vac retard or advance.

Dissy vac is routed off the wrong port. It should come from one of the ported vac(PORT) ports, not the Throttle Positioner port.

For now, the CB should be connected to the TP port.

Cap off the Power Brake booster fitting on the back of the intake. Better yet, get some booster vac vose and connect the PB booster to the PB manifold fitting.

Connect the PCV hose to the PCV fitting on the side of the intake manifold.

Connect the carb Evap port to the canister valve. If there is no canister, then cap the carb port.

Pics may help:
crbfrt.webp
vac.webp
crbtop.webp
 
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I don't have a pic of the dissy right now. I'll be able to get one friday, when i have a chance to try the setup you filled out in the pics. Thanks for takin the time to do that. It's a 78 but was built in late 77 so it hadn't made the crossover yet and still has a condenser...
 
If you want to get rid of the carb temp sensor......can I have it? I need one for my CA spec 78 FJ40 for smog testing.


Is your rig a FED, CA or High Alt spec?

Maybe these will help......

4-4 is the '78 FED spec vacuum routing
4-5 is the '78 CA spec vacuum routing
4-6 is the '78 HIGH ALT spec vacuum routing
 

Attachments

Eric_S said:
If you want to get rid of the carb temp sensor......can I have it? I need one for my CA spec 78 FJ40 for smog testing.

Is your rig a FED, CA or High Alt spec?

Maybe these will help......

4-4 is the '78 FED spec vacuum routing
4-5 is the '78 CA spec vacuum routing
4-6 is the '78 HIGH ALT spec vacuum routing
Click to expand...

The pictured carb is Fed spec 1978 FJ40.

If the OP can't come up w/ a CTS, I can prolly find a good one for you.
 
If its not one thing its another

FJ40Jim said:
In random order:
Remove the 2 screws and flip the Hot Idle Compensator rightside-up. Connect HIC top fitting to the blue capped breather fitting. Connect HIC lower fitting to vac port on carb insulator base. Ignore the 3 small vacuum connections.

Cap off other larger vac fitting in the side of carb insulator base since there is no canister purge hose to connect to it.

Remove & discard Carb Temp Sensor (CTS). There is nothing to hook it to now.

There is the remnant of a manifold Vac (VAC) fitting in the top of the intake just ahead of the carb. It should be capped or removed & plugged.

Show us a pic of the dissy. It should not have a condensor because it is fully electronic. It may be a points dissy w/ vac retard or advance.

Dissy vac is routed off the wrong port. It should come from one of the ported vac(PORT) ports, not the Throttle Positioner port.

For now, the CB should be connected to the TP port.

Cap off the Power Brake booster fitting on the back of the intake. Better yet, get some booster vac vose and connect the PB booster to the PB manifold fitting.

Connect the PCV hose to the PCV fitting on the side of the intake manifold.

Connect the carb Evap port to the canister valve. If there is no canister, then cap the carb port.

Pics may help:
Click to expand...

The pics helped a ton. I hooked everything up like you said started it up and it ran much better. not quite perfect but idled well...till the smoke started pouring. Turned if off checked the oil and ended up draining an entire radiators worth of water out of the block. Now weeks later I've had a chance to pull the block apart change the head gasket and put it back together started it up and it wasn't blowing any more smoke but wouldn't idle without the choke pulled out all the way to start then can back it down to about 3/4 without it stalling. If i hold the throttle on I can turn the choke off, but as soon as I let off it dies immediately. Sounds like it's not getting any idle fuel. It was about midnight so called it a night went back to it in the morning checked all the vitals(radiator was empty again with water in teh oil). **** it all! Going to be pressure testing the system this weekend to find out what's going on with it. Just hoping its not a cracked block(the coolant drained out overnight it seems) Then back to making it run right. I'll throw in a pic of where I was in the rebuild when all this went down...so close to driving it.
First Drive6resize.webp
 
I solved the head gasket issue and am ready to get it running good now.

I set up the carb as described by FJ40JIM. It will only start with the choke fully on. Right now the canister is not hooked up at all. I have the fitting on the carb insulator base on the right blocked off, which I believe goes to the purge on the canister? and the large bowl vent on the top of the carb capped off also. I also have the idle fuel solenoid wired to an ignition source and can hear it click on and off with the key. I did find the charcoal canister in a box of parts this weekend, but did not hook it up. It has 3 hoses out of the top (1 of those is hooked up to a vsv?) and one hose out the bottom. the guy i bought it from stripped all the emissions, but it ran when i bought it. Only thing that has changed is that the stock wiring harness components have been replaced with painless harness now.

So the question i suppose is how to get it to idle? Messing around I put manifold vacuum from where the PB goes to the bowl vent on the carb and that made it idle without choke, but i know that's not supposed to be there. Do I need to hook up emissions components to make it run right? I have the original canister and all original wiring in a box.
 
It should run fine under most circumstances w/o the emissions gear.

Not idling w/o choke is usually due to a vacuum leak or a lack of idle fuel. Hooking the manifold vacuum to the bowl vent is strange, but maybe you are getting enough fuel vapor from it to help a bit.
 
I'll keep hunting for a vaccuum leak, i've already plugged the booster hose to eliminate a leak there. i'll check the manifold and carb base, but are there any other obvious answers for vaccuum, most of the vaccuum lines have been eliminated and all the lines are new right now.

Also, could something be clogged in the carb, it was rebuilt recently but maybe there was still something in there.
 
Crack in the bottom of the intake is another possibility that you can sometimes see with a flashlight and opening the carb throttle plates.
Fuel delivery you can check by dribbling fuel a few drops at a time into the carb and seeing if it will idle better.
 
The funny thing is when it was running really s***ty, I set it up like fj40jim said to and it idled good...thats when i found out about the blown head gasket. I repaired that and something has changed since then. Just need to keep looking and figure out what it is.
 
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