God, I hate carbs...

Ok, so I'm trying to get an '81 GSL running. First carb that came with the car had a broken float, so we took that one off and installed another Nikki that had been running about 4-5 months ago. Now this one doesn't work. The car will run on starting ether, and if we pour a little gas in the carb, but then it dies. We're getting fuel throught the return line so we know the carb is getting fuel.

Any tips? A guy I know who had an old RX-3 mentioned a rollover valve, but those seem to be by the tank on our cars. But I'm not sure what year FB this carb came out of. Was the valve ever a part of the carb itself?

Next step for us is to screw around with the accelerator pump, but I wanted to see if anyone here had any advice.

Thanks in advance.

 

are you sure you are not having a fuel pump problem?
I had a 84 GSL that I had to hardwire the fuel pump.
Check the hose coming into the carb wheh you are turning over the engine to see if it is pumping.

 

Well, we checked the fuel return coming back from the carb and it was returning gas. Clean gas too, which we had just put in the tank. And the fuel pump hums nicely when we turn the key to the on position, so we're fairly certain that we're getting fuel to the carb.

 

If the carb is from a later model, perhaps some of the vaccuum ports are not lining up, or something is not working because of the year differential. My suggestion is to take a float out of the new carb, buy a rebuild kit and rebuild your '81 carb. Then you can put her on and troubleshoot from there. To my mind mixing carbs is just adding another level of complexity to the situation.

 

I assume you've checked that the floats are allow the carb to fill up to the correct level?

I've had the floats stick in the 'fill' position before, so I imagine they can get stuck in the 'do not fill' position as well?

Perhaps the easiest way to tell will be when you check the AP...

 

Hey All,

Yeah, this is very similar to what was happening to the original carb I had on my car. Actually, scratch that. This is EXACTLY the problem my original carb had. We couldn't figure it out for the life of us, so we just got another carb to put on. And now we're having problems with THAT one.

The only thing I saw (with my very amature eye) as I took the old '84 carb apart, was that it was rusted and gummed up to ****.

I *know* the carb was getting gas, but it was returning that gas about as fast as the gas was pouring into it.

So here's my newbish question of the day:

How do you check the accelerator pump?

Jon

 

 

Well, now the RX-3 guy is saying that the carb has it's own rollover valve in addition to the one in the rear of the vehicle. Can anyone confirm this?

 

Hopelessly stock, hi! I disagree, carbs dont suck. They are simple mechanical devices and are easy to troubleshoot.

First off, the carb does NOT have any rollover valve in it. If the fuel is returning to tank without filling the carb I need to ask you a qusetion or two.
1- Is the restrictor in the return line still in place? If not the fuel will take the path of least resistence, which is back to whence it came (fuel tank).
2- Can you see any fuel in the carb windows? If so then the inlet valves are letting fuel in.
3- If the carb sat for a long time with fuel in it, its prolly got gummed up/clooged up fuel jets which isint letting any fuel into the engine. Take off the top of the carb and look into the bowls and see if they look clean, or if they have brown gummy varnish in them.
Oh and EFI cars will get gummed up injectors if you let them sit too.

 

My money is on the accelerator pump. Try starting it twice without pushing the pedal down. The fuel pump relay will have gone on for a second each attempt, and filled the carb with fuel.
The bowl towards the firewall is the resevoir for the accelerator pump, too. If you know you're pumping fuel to the carb, and have tried to start the car, then barring a completely clogged screen, you'll have fuel for the accelerator pump to operate.
Look down at the primaries and watch the accelerator pump nozzels (between the smaller venturis) as you operate the linkage by hand, and check out the squirt. If it's not hearty, then the accelerator pump diaphragm needs to be replaced. If there's no squirt at all, one or both of the checkballs are stuck.
If either is the case, then a rebuild is in order.

 

My money is on the accelerator pump. Try starting it twice without pushing the pedal down. The fuel pump relay will have gone on for a second each attempt, and filled the carb with fuel.
The bowl towards the firewall is the resevoir for the accelerator pump, too. If you know you're pumping fuel to the carb, and have tried to start the car, then barring a completely clogged screen, you'll have fuel for the accelerator pump to operate.
Look down at the primaries and watch the accelerator pump nozzels (between the smaller venturis) as you operate the linkage by hand, and check out the squirt. If it's not hearty, then the accelerator pump diaphragm needs to be replaced. If there's no squirt at all, one or both of the checkballs are stuck.
If either is the case, then a rebuild is in order.