No fuel in second barrel?

[p89]

I am a proud owner of a Honda Accord -89 with a carburetor. It’s an old car but I like it very much anyway. Easy and fun to drive and the fuel economy is great. But there’s a strange problem that I haven’t found yet. When I press the accelerator almost to the floor, the engine loses almost all power. If I relese the pedal a bit it revs back up again. This problem shows up as soon as the engine is warmed up but not before. I have tested quite a few things with vaccum and emission control stuff. I’ve checked the EGR components, fuel pressure (2,8 psi, witch is sufficient according to the Haynes repair manual), float level, timing advance, timing, valve clearance. Everything seems to work OK. Yesterday I tried to test the vaccum controlled secondary bore in the carb. This function seems to be active only when the engine is warmed up, vaccum is controlled by thermovalve C, I guess. It seemed to work fine, port opened when I gave it full trottle. But I don’t know if there was any fuel coming in to the second bore at the same time. So my question to all you experts out there, finally is: what is controlling the fuel inlet to the second bore? There is a carb thermovalve close to it, has that something to do with the fuel to second bore? Any ideas what I should try next? Pelle K

[A20A1]

Vaccum throught the venturi pulls fuel out... as long as you're getting the second barrel to open then fuel should be coming out. Though some of it is load dependent so the more load you'll see more fuel, free reving in neutral might not show as much.

The thermowax valve on the thermostat housing bleeds the vacuum when the motor is cold, thats why the diaphragm doesn't hold vacuum. You should connect the vacuum pump directly to the diaphragm when testing the diaphragm.

Once the car warms up then you can test the vacuum "T" to see if the thermowax valve is no longer bleeding vacuum. Remove the vacuum line from the carb and connect the pump vacuum line in it's place.

Remember the secondary is partially venturi vacuum operated so it needs a air about of flow through the primary barrel for it to work.



If fuel is a problem then I would check you booster venturi.

If the booster venturi is not tight then the seal between the booster and the outer edge of the barrel will leak vacuum and that will cause the fuel to have a hard time getting pulled into the secodnary barrel.

Read through the posts I made in the link below.
https://www.3geez.com/showthread.php?t=8972

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[p89]

Thanks for your quick response.
I've checked the booster venturi and i'ts solid. And since you say that fuel is sucked in by engine vaccum I pried a small hose over the tube in the center of the booster venturi and managed to suck out fuel so I guess that means that the carb isn't clogged either.
I also checked the vaccum secondary as you said and it seems to work fine.
Maybe I'll just have to move on and look for the problem elsewhere than in the carb.
I can't help thinking that the problem is second barrel related ,though. I mean, I have no problem revving up the engine to 6000 rpm if I'm easy on the trottle, it's when I press the trottle beyond a certain point as the the problem occurs(with hot engine) And that point should be when the second bore opens.
Thanks again for your input.
Pelle K

[p89]

I thought I might contribute with something to this exellent forum.
A vaccumpump cost almost as much as a third generation honda, at least here i Sweden. This is much cheaper, the syringe I got for free at the chemist and the vaccumgauge does'nt cost much either. And it actually works.
Pelle K
There should be a jpg here but I must have done something wrong.

[A20A1]

When you upload copy the code and paste it in your post... if you just attatch the image and click post it wont add the image, you need to copy and past the code.