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hatepotholez

Engine only runs with starter fluid

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Hello everyone, making great progress on the Z. Two weekends ago we got the car running. We used starter fluid to start her up and then light throttle to keep her on.  The week after I buttoned up most of the fuel lines and a quick spray of the starter fluid we got the engine running again and maintained with throttle.

We tried to start it again yesterday and it started up without starter fluid. Yesterday I tried again, no luck, tried starter fluid but stays on then dies even with throttle application.

 

 We are getting fuel at the carbs, I am assuming there is a blockage from the float bowl to the dampers. Also I know for sure the timing is off but I wanted to set the timing with the engine running.

 

Any advice would be greatly appreciated.

 

Thanks!

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The nozzles maybe too high. Turn the adjustment knob counter clockwise 2.5 turns from the top. They could be stuck, do the nozzles move down when you pull the choke?

They're under the carbs. The hose from the bottom of the float chamber connects to the nozzles on the bottom of the carb bodies.

Sorry I can't show you pics now, on my dumb phone.

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The nozzles maybe too high. Turn the adjustment knob counter clockwise 2.5 turns from the top. They could be stuck, do the nozzles move down when you pull the choke?

They're under the carbs. The hose from the bottom of the float chamber connects to the nozzles on the bottom of the carb bodies.

Sorry I can't show you pics now, on my dumb phone.

 

Ok i'll check that out. In the meantime I will look for a SU manual as I am used to Webers.

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Front carb.  #19 is what I'm talking about.  Tighten it all the way up, then go counter clockwise 2.5 turns for a general setting.  There's TONs of stuff on here about these carburetor.  I think it may have it's own sub-forum?  It does, http://www.classiczcars.com/forum/71-carburetor-central/

 

Whoops, I see your in the forum now.  :facepalm:

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Thanks! My buddy tried to remove the float plate, but looks like it won't come off due the main carb having a tab over it? Do I have to remove the carbs off the manifold to get access to the float chamber?

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Nope The float chamber is alongside the carb body. The fuel enters into the top of the float bowl. 3 or 4 screws & probably a new gasket.

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I think you are talking about the metal "bracket" (used for lack of the correct word) that has to be bent down around the fuel inlet on top.  You can take the screws out like Mark says and that bracket will be loose, lay it off to the side and gently pry the lids off, probably still tearing the one use gaskets.  :(   

 

Here's a picture of what I'm talking about, it's called a brace.  The big bolt with the internal fuel filter goes through it.  Bottom right corner of this picture is the thing that has to be bent to loosen the banjo bolt.  Probably confusing you more as I'm no good at explaining, sorry.

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Get the DVD "Just SUs" from Z Therapy, it's a must if you've got SU carburetors that you want to work on. 

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Ok the plot thickens, I have or(had) gas coming out of the float tube going to the nozzle. This is exactly where the fuel stops. No fuel comes out of the nozzle under the dampers, bone dry. Took apart the front carb, looked decent and set the float. I followed the service manual and back out the fast idle screw and balance screws and then tightened and turned back the nozzle adjusting screw by 3 turns based on ambient temps, I also then put 2 more gallons of gas, I have at minium 4 gallons of gas.

Next step, used carb cleaner to the nozzles, there was no blockage.

Then attacked the fuel pump. I disassembled the fuel pump which was dirty but nothing looked clogged, and put it back together. I then removed both hoses off the fuel pump and put my fingers over them and felt no suction.

Ill try and rebuild the pump and replace the internals with new parts or get a new pump.

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I should add that before I dissasembled the fuel pump my fuel filter never passed the halfway mark, now its at the 25% mark. I beleive the fuel filter should be full at all times?

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How much fuel is visible in the fuel filter in not important, nor is it a reliable indicator of fuel flow. Try using a remote fuel tank to run the car via gravity feed to the carbs. If it runs then you know the carbs are ok and the problem is the pump or a problem in the fuel line somewhere.

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Is it a mechanical pump or electric?  If it's mechanical you won't feel much air just turning the motor with the starter. 

 

Those little hoses have to be just right or they'll kink and you'll have no flow between the float chamber and the carb.  My red 240 had some rock hard 1/4"? fuel line on those carbs that wouldn't let the nozzles move down.  Hard to start.

 

I did what Beerman says, put a 2 gallon plastic gas jug in front of the radiator and ran the 2 lines into that and the car ran fine.  Then dropped the gas tank and cleaned all the crap out.

 

When I bought mine the valves were so far out of adjustment it took forever to start.  Set them and then it would start as soon as I turned the key. 

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Before I hooked up the fuel lines we had a remote bottle of fuel straight to the pump and it worked. I then connected the fuel filter to the the mechanical pump and lines and it ran on thrtottle but no idle this happened 2-3 weeks ago.

After tearinfg apart the fuel pump and not getting fuel I disconnected fhe fuel filter on the output side and it was dry. The tank was emptied and cleaned before I installed it. How long does it usually take the system to prime on a bone dry system?

Edited by hatepotholez

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Here is the "tab" that is on the damper body. This tab makes it difficult to remove the float. I had to turn the float plate almost 360 degrees to leverage it out.

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You can do without those rubber tabs. I cut mine off, they're for alignment and if you get the screws in barely tighten them and raise the piston in the carb body. If it falls at a smooth rate tighten the screws.

I'd pull the valve cover off and work that arm that rides against the cam nose by hand until you get fuel to the float chambers.  You can check for fuel in the chambers by sticking a red WD-40 straw down the overflow bung then pull it out to see if it's wet. 

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I misunderstood your tab reference, sorry.  I thought you were talking about the rubber stopper under the dome.  Now I know.  

 

Take the 4 screws out.  Turn the float chamber lid 90 degrees counter clockwise.  there's 2 indentations on the sides of the lid.  You'll have to gently wiggle it around the tab, keeping it flat against the bowl, working the indentations under the tab.  It'll pull up and out.

 

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I misunderstood your tab reference, sorry.  I thought you were talking about the rubber stopper under the dome.  Now I know.  

 

Take the 4 screws out.  Turn the float chamber lid 90 degrees counter clockwise.  there's 2 indentations on the sides of the lid.  You'll have to gently wiggle it around the tab, keeping it flat against the bowl, working the indentations under the tab.  It'll pull up and out.

 

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No worries, thank you for this! very useful. Now if I can only get pressure in the system  :(

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Update time, Mech. pump was not pulling after multiple cranks. So I took a syringe and put gasoline into each float bowl. I squirt in some starter fluid and the car turns over and stays on but I am modulating the syringe on the vent on the rear carb and this keeps the engine running but eventually dies for no gas. I then install a low pressure fuel pump that supposedly outputs 2-3.5 psi, when this pump is on for too long, gas overflows on the front carb from the vent and nozzle. I did not install a regulator yet. The rear does not overflow so I assume the needle and seat is clogged. I slightly hit the side of the rear float bowl and now gas is coming out from the vent and the nozzle as the front was. I then check the float, looks ok but did not take the needle and seat apart.  

 

Tomorrow I will install the pressure regulator and see if it will run continuously. Even though the fuel is flowing out of the float bowls the car still only runs on starter fluid and no fluid is coming out of the nozzle(unless I am not supposed to see it when cranking). Forgot to mention on the old plugs the first 3 were dry, the rear 3 were wet. I then installed new plugs. 

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3 psi shouldn't overwhelm the float valves. Makes sure the floats are set properly and seal when shut. 1st things 1st...

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IMO No need to remove the carbs. The problem is in the floats & valves as Patcon said. Properly operating f. valves should be able to handle 4 psi.

 Remove the float covers & dash pot domes.  Don't bend the needles. Clean everything up, fix the float & valve problem, check mixture needle height, operate the choke & ensure the nozzles are moving down & up, set the mixture screws (nozzle height) 2 1/2 turns down & do a drop test on the pistons (dash pots). It should run at this point in time.

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My floats before adjustment, overflowed.  Set the top of the float .550" from the underside of the lids.  And the front carb has the taller float valve, if they're the same, add washers. 

 

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Thanks for the reply guys.

 

The pots drop down evenly and make a clunk. I'm sorry but how do I check the mixture needle height?

 

Another update, took apart the rear float, everything looked ok but the float needed a slight adjustment, I believe it was sitting at 10mm high. I cleaned the needle, seat and adjusted the float(15mm). Vehicle still needed a quick squirt of starter fluid and then the car remained on her own but needed constant depression of the gas pedal to stay on(choke was fully on). A little after the car was able to stay on without pressing the gas pedal. I checked timing and it was ridiculously off but that's another topic LOL. I ordered the carb rebuild kit and will tackle it next weekend. At this point the nozzle looks to be ok, might have to correctly adjust the carb cables also.

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I can't remember how to set the needle right off my head this morning, it's a little fuzzy.  LOL

 

I'll scan through the DVD today and see how, it's something simple.  Maybe someone else will remember for me.  That DVD is a treasure at the bottom of the sea, but watching it is like the boat ride to the treasure.  It's a little rough and makes me motion sick.  ROFL  

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 IMO The easiest way to set the needle height is; Turn the mixture screws all the way up, keeping track of the number of turns. Remove the piston, loosen the needle set screw, pull the needle out about an 1/8", tighten the set screw just until the needle won't fall out. Install the piston & chamber, using a pencil or other soft item push the piston down using the oil access hole on top. The piston should move down about 1/8". This will bottom out the needle against the nozzle, which is the proper height. Remove the piston tighten the needle & reassemble. 

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