How do i test if my secondaries are working properly?
Thread Starter
Joined: Jan 2008
Posts: 1,300
Likes: 60
From: Southfield, MI
Hey guys i need help with my secondaries because the car idles and the performance is beautiful until i hit 4th gear at full throttle at around 4000 rpms it starts bogging like it does not have enough fuel, this is when i am at full throttle, when i ease the accelerator in it does not happen. I have a feeling my secondaries are not opening because i opened the throttle completely with the engine of and i see no way of the secondaries opening, or at least i think so. need some help on that and just to throw it out there, when i break with my gear box and throw it in neutral again and brake it wants to turn off and the idle just goes below 600 and i have to accelerate it and it stabalises again. need help on that too. thanks
I think he would see this symptom in all gears, not just the midrange to top of fourth with the fuel filter being plugged. I would replace it anyway because it's cheap, but I don't think that this is the root of the problem. If the cats are clogged, then it would kill the performance through the powerband, whether he's in gear or just free revving the motor. I'd suspect that a weak fuel pump would be the main cluprit to check after replacing the fuel filter.
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Typical example of a clogged fuel filter:
Run the car hard through the gears, redlining 1st/2nd/3rd gear, then all of a sudden the car falls flat on it's face. What happens is that you are using all of the available fuel stored in the float bowls and filter, faster than the filter will let the system refill itself.
Change your filter, then check to see if the problem persists....
.
Run the car hard through the gears, redlining 1st/2nd/3rd gear, then all of a sudden the car falls flat on it's face. What happens is that you are using all of the available fuel stored in the float bowls and filter, faster than the filter will let the system refill itself.
Change your filter, then check to see if the problem persists....
.
A simple way to check if the secondaries are working is to cut out a piece of cardboard that covers over the secondary barrels. At idle and slow acceleration, the car will behave normally if you punch it or go above ~3500RPM it will bog and fall on it's face because of the cardboard choke. If it bogs, they work; if not then you have some investigating to do.
Thread Starter
Joined: Jan 2008
Posts: 1,300
Likes: 60
From: Southfield, MI
is the red to black and black to red for the sensor thing in the carburetor secondaries side? I think i have that sensor disconnected, ill check if its getting any electricity as my car is an electrical reck and see if that helps. thanks ill check back with you guys after i change the filter, check if the secondaries are working and see whats the deal with that sensor.
You can always hook up mechanical secondaries to be sure 
Sounds like the fuel filter. If it was the secondaries you'd have trouble driving the car around, it would be super slow. Atleast thats how my car felt without the secondaries.

Sounds like the fuel filter. If it was the secondaries you'd have trouble driving the car around, it would be super slow. Atleast thats how my car felt without the secondaries.
I would change the filter and "T" in a temporary fuel pressure gauge on the fuel line. Then run the gauge in the window and check pressure during wot passes. Harbor freight sells cheap fuel press test kits. 
Also.... If you’re redlining all your shifts, you should be around 7k+ in 3rd before shifting to 4th. Doesn't 4000rpm seem like a hell of a drop in RPM for a Wot shift into 4th? Sounds to me like your just not revving it high enough in 3rd before shifting and the car bogs because the engine doesn’t make as much power down low in the RPM range. .
Gotta rev these little bastards if you want to go anywhere!
Good luck, let us know what helps.....

Also.... If you’re redlining all your shifts, you should be around 7k+ in 3rd before shifting to 4th. Doesn't 4000rpm seem like a hell of a drop in RPM for a Wot shift into 4th? Sounds to me like your just not revving it high enough in 3rd before shifting and the car bogs because the engine doesn’t make as much power down low in the RPM range. .
Gotta rev these little bastards if you want to go anywhere!
Good luck, let us know what helps.....
Nikki-Modder Rex-Rodder
Joined: Feb 2001
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From: Trying to convince some clown not to put a Holley 600 on his 12a.
Leave the floats alone. Check the fuel filter. Check the "teetor-totter" linkage gizmo. And if you want to see what the car runs like without secondaries, simply unhook the link that the vacuum box lever moves. Be sure to run the **** out of her before and after so you can compare. If it's the same, then it's possible the vacuum propt circuit is clogged with oil/fuel residue between the throttle body and the main body. But that's only something that happens over long periods of sitting.
If it was fine and suddenly there's a power loss, then it's most likely that bit of linkage.
If it was fine and suddenly there's a power loss, then it's most likely that bit of linkage.
Thread Starter
Joined: Jan 2008
Posts: 1,300
Likes: 60
From: Southfield, MI
ill check that out. when you guys told me about the cardboard thing on the secondary barrels was that test supposed to be done in a stand still and just rev it or actually driving?
For Pete's sake! Would you just change your darned filter already?!? 
It takes only a few minutes. Costs only a few dollars. And if you haven't changed it in the last several months then it needs to be replaced anyway.
Start with the obvious, then continue with the troubleshooting. Otherwise, you might just end up messing up something that was correct to begin with and compound both the problem and the troubleshooting process.....

It takes only a few minutes. Costs only a few dollars. And if you haven't changed it in the last several months then it needs to be replaced anyway.
Start with the obvious, then continue with the troubleshooting. Otherwise, you might just end up messing up something that was correct to begin with and compound both the problem and the troubleshooting process.....
Others have already supplied good info. Here are some pictures to go with it.
First make sure your Throttle return is
like this

Not like this

As Sterling said earlier, to test the secondaries remove the cotter pin from the secondary diaphragm lever and disconnect the arm. If still the same secondaries are not working. Vacuum signal comes from passages built into the carb body. No lines. You can see the arm sticking out below the Secondary throttle diaphragm cover here. Just to the left of the Throttle position sensor above the richer solenoid plug.

Ron
First make sure your Throttle return is
like this

Not like this

As Sterling said earlier, to test the secondaries remove the cotter pin from the secondary diaphragm lever and disconnect the arm. If still the same secondaries are not working. Vacuum signal comes from passages built into the carb body. No lines. You can see the arm sticking out below the Secondary throttle diaphragm cover here. Just to the left of the Throttle position sensor above the richer solenoid plug.

Ron
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