quadrajet fuel filter

[bp71k5]

It seems like several people have posted about these fuel filters causing a lot of problems.

I have problems after removing a second inline filter (fram) right before the filter in the carb and it was running fine. Once I replaced my fuel line from the tank and mechanical pump, removed the inline filter ,and replaced the in-carb filter, I have gas pouring out at the top of the carb where this little plunger dips in. (see arrow).

Is this one of the typical problems with the filter? It's odd because it worked fine with the old filter in there so I'm not sure why adding a clean filter would cause problems. In any case, gas is getting in there ok so it would seem to not be plugged.

Any ideas what's going on?

 

[ryoken]

thats the accelerator pump. theres an o-ring seal in the cover housing that the shaft rides thru. it needs to be replaced.. comes in a rebuild kit... has nothing to do with filters...

 

[bp71k5]

Thanks, that's sort of good news.

I did find that when I was replacing the filter, the rubber cap on one of the vaccuum ports split and was causing a vaccuum leak. When I fixed that, the fuel coming out of the accelerator pump is now very little and the motor runs much better.

Before I fixed it, the motor was running bad on only a few cylinders so I'm guessing the fuel bowl was filling up with all the extra fuel not being delivered and forced it out that area.

Bad news is that I can't have gas dripping off the carb while driving so it's going to need to be fixed.

I was able to find a bunch of rebuild kits for other quadrajet carbs, but nothing with my carb number. Anyone have a good source of rebuild kits for a Carter Quadrajet number 4850-S? I've rebuilt some weber carbs when i was a teenager, but nothing this complicated. Is it a simple DIY job or is it worth paying someone to do it?

 

[Hogback Fabrication]

I was able to find a bunch of rebuild kits for other quadrajet carbs, but nothing with my carb number. Anyone have a good source of rebuild kits for a Carter Quadrajet number 4850-S? I've rebuilt some weber carbs when i was a teenager, but nothing this complicated. Is it a simple DIY job or is it worth paying someone to do it?

If you've rebuilt a carb before you shouldn't have trouble with this one. Just make sure everything is REALLY clean and blow out all the passages with compressed air.

Have you tried NAPA or Carquest? They are generally much better than the other parts stores.

 

[bp71k5]

Thanks for the tip, I've got a Napa down the street. I'd prefer to just replace the gaskets or seals unless somethings really wrong with it. The carbs I've rebuilt before were just 2bbl vw carbs and not very complex. In addition, those carbs never seemed to run any better after I got done with them. Maybe I'll see how far I can get without damaging anything and then take it to a pro if it doesn't work.

 

[Hogback Fabrication]

To get a new accelerator pump you will have to buy an entire rebuild kit. It should be around $20.

Here is what it takes to replace the accelerator pump:

You will have to take the accelerator pump lever off by punching a pin through its hole in the carb (this pin is what the accelerator pump lever pivots on). Then remove the secondary rod (you just have to fiddle with it to get it out of the choke pulloff). Then remove the small clip that holds the choke rod on and disconnect the choke rod. Then remove the 6 or 8 screws that hold the top of the carb on and remove the top piece of the carburetor. Now you can replace the accelerator pump and reassemble. Be careful to keep everything REALLY clean.

 

[bp71k5]

Just checked Napa online and they have a kit listed for my carb number. Thanks for the tip! I keep forgetting the motor came from a 69 chevelle so it makes finding parts tricky.

 

[pauly383]

I found a pick/pointy tool with a 90 degree bend will push the pin out the front from the backside of the accelerator pump fulcrum area

 

[mosesburb]

I have gas pouring out at the top of the carb where this little plunger dips in.

If you have fuel POURING out around the plunger, it sounds like you have a stuck (or sunken) float or a piece of debris in between the needle and seat. A little residue around that area could be accepted as normal, but any quantity of fuel constitutes a problem. If you get a carb kit also get a new float. Check the kit while you are there and verify that it has a accelerator pump assembly in it. Most kits only come witht the rubber seal at the bottom to be installed on your old pump asm. Also, I have never seen an automotive Q-Jet with an o-ring around the accel pump shaft, so don't be surprised if you don't find one in the carb or the kit.

 

[ryoken]

Also, I have never seen an automotive Q-Jet with an o-ring around the accel pump shaft, so don't be surprised if you don't find one in the carb or the kit.

this brings up an interesting point... honestly it's been ages since I did an "automotive", I do hundreds of marines... And O-ring would be a poor description too.. It's a black 4 sided seal and it goes in the upper housing... Honestly I don't remember whether I remember seeing them in non-marine apps...

 

[bp71k5]

Ah, now you guys have me worried. I can see what looks like a black 4 sided rubber piece in the service manual diagrams. I assume that's what you mean.

There used to be fuel "pouring" out of that area. Once I fixed the vac leak, it's just a tiny bit.

Since the kit is not expensive, it sounds like it's worthwhile to clean the thing up and replace the gaskets and seals as long as I don't screw something up while doing it.

Thanks for the tips.

 

[imiceman44]

Ah, now you guys have me worried. I can see what looks like a black 4 sided rubber piece in the service manual diagrams. I assume that's what you mean.

There used to be fuel "pouring" out of that area. Once I fixed the vac leak, it's just a tiny bit.

Since the kit is not expensive, it sounds like it's worthwhile to clean the thing up and replace the gaskets and seals as long as I don't screw something up while doing it.

Thanks for the tips.

The last kit I got which was last month had all the parts needed, including the seal, the accelerator pump complete, etc...

 

[jms]

I've gone thru a similar issue - fuel coming out at the accelerator pump pin. In my case, it was the 'skirt'-looking (for lack of a better descriptive term...) kinda gasket of the accelerator pump thingy itself. Replacement part was in the carb rebuild kit.

 

[bp71k5]

I can confirm this today as Napa actually had the kit (and a float) in stock. The accelerator pump pin has a black rubber gasket on the end.

Thanks for all the help.