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hatepotholez

no fuel going to rear carb

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So I found something strange. My rear carb is not being fed fuel at times. I disconnected the fuel lines from each carb and placed plastic bottles on each line. I then put fuel in the bowls and let the car run.

Doesn’t matter if it’s a mechanical or electric pump. If the front fuel line is plugged the rear will get fuel. I’m guessing it’s either clogged fuel lines in the rail or the return valve(this is not installed) or whatever that sits near the coil.

 

 

Any thoughts?

 

thx

 

 

 

 

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That definitely sounds like a partially blocked fuel rail.  I suggest removing it from the car and back flushing it with whatever pressure you can apply - perhaps an aerosol brake cleaner product.  I'd start at the rear carb port, block the front carb port, and have a wire inserted in the supply port to break up any material that arrives.  Then block the rear carb port, repeat the process for the front carb port.  If the return line is open, you'll see some output during the process - that could also be a tiny wire insert to break up anything.  Check your results by applying liquid under pressure at the supply port to see if both carb ports are open.  The flow guide valve under the coil only handles vapors, not a likely culprit.

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Thanks, Ill try this out. I am also wondering if the lines from the tank to the pump are good. All lines are new including fuel and brake, even though the car sat unused for over 10 years.. The rail is original. 

Edited by hatepotholez

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Ok ran brake cleaner through the rail and compressed air, still getting very low pressure, low enough that it barely fills the carb bowls. If the tank is not vented properly can this affect the flow? I put new hoses from the tank to the vent tank but maybe the connections are crossed.

I also have to check the lines from the tank to the pump. Kind of hard now since I have a full tank of gas.

Lastly i’m going to try and get a remote fuel tank connected to the pump directly and see if that helps.


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ok good news and bad news. Good news is I think i found the issue. I ran a remote fuel bottle and the fuel pump sucked it through quick and maintained high float levels.

I then blew air through the fuel line from the tank and gas was gushing out. After this I stuck a borescope down into the fuel tank and saw large pieces of the coating floating all around. This is what must of caused the fuel system to have low volume, it must of partially clogged the fuel exit port. After this I reconnected the fuel line and the floats were at a much higher level and the car was running very smooth. The floats still need to be adjusted but the tank has to be cleaned first. Ah what a sigh of relief!! Dreading dropping the tank though 🤦🏽‍♂️


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Have you installed a clear filter coming out of the tank? A fram g3 works better on 240's smaller hose in my opinion.  They're  cheap to. You might use a couple and get the crud if it's  not too bad.  240 tanks are jobbie job!  You have to deal with all the evap hoses.

Edit: G2 is the 5/16 for 240s. G3 is 3/8 for 280s.  My bad.

Edited by siteunseen

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On 1/4/2019 at 3:56 PM, siteunseen said:

Have you installed a clear filter coming out of the tank? A fram g3 works better on 240's smaller hose in my opinion.  They're  cheap to. You might use a couple and get the crud if it's  not too bad.  240 tanks are jobbie job!  You have to deal with all the evap hoses.

Edit: G2 is the 5/16 for 240s. G3 is 3/8 for 280s.  My bad.

I installed a few filters, but they weren't clear. It's not really crud, more like big flakes of lining floating around. 

I'll see if I can upload the video. 

 

Edited by hatepotholez

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To add to my reply, none of that crud would stick to a magnet.  Car sat for 10 years with fuel in it.  It was just crumbly crud that smelt like fuel. I even tried to burn a piece with no luck. I think the fuel and moisture combined to make that mess?

Let me know if I can help, I have the threads with evap sizes from O'Reillys auto and what I bought from Lowe's. Also my Jimmy rig for the 90 degree turn on the top hose. Two 3/4" PEX fittings works great. Shade tree restoration, no show winner stuff. LOL

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Thanks, I appreciate it.

This weekend i'll be dropping the tank and sending it to a radiator shop. I didn't want to do this job but i'm just being lazy lol!!

 

i'll keep you guys updated!

 

I attached the pic, hopefully you can see the large lining flakes.

 

240z lining floating.png

Edited by hatepotholez
pic modified

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It's a pretty big job for a 240.  You may just buy another car? LOL

I've never seen a new tank for the 240s and I've read from end to the other.  There is a guy on ebay that makes an aluminium one for about $2,000.

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wow that’s expensive, i’ll stick to mine lol!

 

Some progress, tanks out and will be send to get boiled out this week, hopefully it gets rid of all the lining and whatever junk is in there.

On another note, my float bowls are at the right height since adding gas into the bowls but the car won’t start. When I spray starter fluid it immediately starts. I’m pretty sure the starter fluid is more volatile but I have the right amount of gas in the bowls, the chokes are on and i’m pumping the gas pedal. Why won’t it run?

 

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1 hour ago, hatepotholez said:

 

On another note, my float bowls are at the right height since adding gas into the bowls but the car won’t start. When I spray starter fluid it immediately starts. I’m pretty sure the starter fluid is more volatile but I have the right amount of gas in the bowls, the chokes are on and i’m pumping the gas pedal. Why won’t it run?

 

1

 If these carbs are the early round tops, they have no accelerator pumps. Pumping the gas pedal won't add fuel, it will add more air. Have you tried starting it with fuel in the bowls, full choke, and no throttle?  I'm a bit surprised it won't start and run even for a short time with fuel in the bowls.

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10 hours ago, Mark Maras said:

 If these carbs are the early round tops, they have no accelerator pumps. Pumping the gas pedal won't add fuel, it will add more air. Have you tried starting it with fuel in the bowls, full choke, and no throttle?  I'm a bit surprised it won't start and run even for a short time with fuel in the bowls.

I’m not sure how early, but they are roundtoops and my Z is a ‘72.

Ill try without pumping. 

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With the choke pulled back and the nozzles dropped all the way my 72 doesn't need any pedal to start.

I had a 240 that wouldn't crank right up when I first bought it.  Adjusted the valves to spec and it would fire up instantly.

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