rear su carb not fueling

[Costjo]

My car was running perfectly till this morning it started right up and then just bogged and died.

I figured it wasnt getting fuel. So then I checked the fuel filter which was a clear glass filter and it was super dirty. I replaced it and got car running but it was running super rough like it was missing and sure enough pulling the wires on back 3 plugs while running and it didn't stumble.

So now I think the rear carb has issues. Could the needle be clogged from dirt that got through?

While it was running I pinched the idle mixture hose from the float it didn't stall so it seems like it isn't getting fuel.

Is there a way to check the back su carb to know if its functioning?

I pulled the fuel hose going to float bowl and it was getting fuel to that point. I just not sure what to check next. I dont have much experience with these carbs any help I would appreciate helping me as a beginner.

Thanks, Joe 1972 240z

[Stanley]

The search feature near the upper right of this page is pretty good. I lot of times I've wondered about stuff and thought about posting a question, but then found plenty of information from posts on the topic with the search.

Anyway, if the dirt in the filter was reddish, it's probably rust in the gas tank. There's a drain plug on the tank, maybe do some jerky driving to stir it up and pull the plug, put some clean gas and do it again, might fix it temporarily. There are threads about cleaning the tank. If by the needle you mean the valve in the float bowl, yes, they can get gunked up, there's usually filters inside the banjo bolt where the fuel goes to the bowl. they can be removed and cleaned with carb cleaner. Also gunk can collect in the float bowl. If you have an electric pump behind the right rear wheel, it has a filter that can get clogged up.

The FSM explains adjustments. Also ZTherapy video and various posts.

Good luck, the SU's are very simple but also advanced technology, good for street, even for racing with the right preparation. just don't wreck anything by using too much muscle on steel screws in aluminum. Might just need a little carb cleaner.

Bad plugs, points, etc. can also have those symptoms, so maybe a combination of causes.

And maybe buy some float bowl gaskets before taking it apart.

Edited February 9, 2014 by Stanley

[Bruce Palmer]

Don't over look the final filter in the float bowl lid. Could be all plugged with that crud you saw. Also clean the needle and seat and see what that combination of tasks gets you......

[Costjo]

Would that be the banjo bolt small round filters? I haven't opened the lid yet don't have any gaskets. Does the drain screw on float bowl need a new washer after opening or can I just drain it and put back on?

Don't over look the final filter in the float bowl lid. Could be all plugged with that crud you saw. Also clean the needle and seat and see what that combination of tasks gets you......

[Stanley]

"small round filters?" Yes.

And don't need a washer.

When you remove the lid/float assemblies turn them 90 degrees to remove them, also easier if some of the gas is drained out. Don't lose the little wire clips that hold the float valves together when you remove them, they jump off and go flying.

Edited February 11, 2014 by Stanley

[Costjo]

These? Carb Filter Banjo Fitting 70-72 240 & L4 engines: Engine Z - Fuel - Carburation - 30027-ECB - Z Specialties Online Store - If we don't have it in stock, we can get it!

"small round filters?" Yes.

And don't need a washer.

When you remove the lid/float assemblies turn them 90 degrees to remove them, also easier if some of the gas is drained out. Don't lose the little wire clips that hold the float valves together when you remove them, they jump off and go flying.

[Captain Obvious]

Yes, those are the filters in question.

If you've pulled the fuel line and verified that you're getting fuel TO the carb, but not getting fuel IN the carb, then that filter is most likely plugged with the same crud that you found in the clear glass filter.

BTW - I have very little faith in those clear glass filters with the cleanable plastic screens. I don't think they are very effective. And if you find your banjo filter plugged, that would be corroboration...

[Costjo]

What filter do you recommend?

Yes, those are the filters in question.

If you've pulled the fuel line and verified that you're getting fuel TO the carb, but not getting fuel IN the carb, then that filter is most likely plugged with the same crud that you found in the clear glass filter.

BTW - I have very little faith in those clear glass filters with the cleanable plastic screens. I don't think they are very effective. And if you find your banjo filter plugged, that would be corroboration...

[Captain Obvious]

Pretty much anything disposable with a paper element would be better than those clear glass ones.

Most people just use the ubiquitous Fram G3:

[Travel'n Man]

Call Bruce above and get some carb bowl gaskets - they will curl up on your like pretzels.................sounds like to may want to pull your tank - have it sealed and start fresh. If your clear filter is in line with your tank (and nothing between) really sounds like sediment and rust in the tank. With this type of problem you must find the root of the problem and fix it. If you do pull your tank it's a great time to freshen all your vent lines and fill tube. Refreshing these lines will help reduce the fuel smell in your Z's interior as well. If you do take your tank out - right above the sending unit on the tank is the ground wire for the sending unit. Unscrew it and get your connection bright and shiny - it will help your tank reading on your fuel gauge. Also the other end of the wiring harness (in the back hatch area - right next to your passenger tail light) is the spade connectors...........pull them and clean with a small file to ensure good contact - this is what powers your signal to your fuel gauge....................one project always leads to a few more..........but all worthwhile.

[Costjo]

Thanks for all the great suggestions. I got it working again.

I ended up changing the glass filter which had crud in it and made sure I got fuel to the carbs. Then I cleaned the small banjo bolt filters and drained out the float bowl. Im not sure If I should of done this but sprayed into the 3 holes on the float bowl with carb cleaner. I never opened float bowl because I don't have any gaskets. I reconnected everything and she started right up.

The next day I saw this so I bought some Techron and put in tank hoping it will clear it up. Actually after I started it again it is now clear so something overnight caused that.

[Costjo]

Thanks ill give that a shot. Can I ask what is wrong with the clear ones?

Pretty much anything disposable with a paper element would be better than those clear glass ones.

Most people just use the ubiquitous Fram G3: