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GregP

Looking fro help with fuel issue

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My 73 Z won't start. Turns over and starts with a few squirts of starter fluid then dies unless I keep squirting it in. Assumption is that it's not getting gas. I changed out the fuel filter and no difference. Plenty of gas in the tank. The engine was rebuilt a few years ago and the carbs all redone by Z therapy. Ran beautiful for the last few years (only about 500 miles put on it.)  It would start right up.  Since the rest is all original components I assume I have just the mechanical fuel pump in the front  passenger side of the engine which I believe a new one was put on after the engine rebuild.

How can I test it to see if that's the problem? If I take the line off that comes from the filter should I feel suction when cranking the motor?  

What else could stop the fuel if the filter and fuel pump are ok? Is there a pick up tube in the tank that might be clogged?

Is there a step by step procedure to test and eliminate things?

Thanks,

Greg

 

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 I doubt the problem is in the carbs. Both carbs rarely go bad at the same time and the engine will run (or try to run) on one carb. I'd start with a fuel pump check. Fuel pressure and fuel volume need to be verified. The test is available in any Z repair manual and a gauge can be borrowed from a parts store. No fuel to the float bowl possibilities are; clogged banjo filters on the carbs, bad mechanical fuel pump, Loose eccentric that drives the mechanical fuel pump, plugged lines, it's possible you also have an elec. pump and filter back by the tank. If so both should be serviced, Rust, flotsam and jetsam in the tank blocking the line is common. 

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If the mechanical fuel pumps sit for a while, the internal valves can stick shut. If the pump is serviceable, you can disassemble and make sure the diaphragm is good and the valves move

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I took the pump out to manually test it. I needed some fuel line so I stopped in at O'Reillys and while I was there I borrowed a test gauge.

I just got back and while looking the pump over I tried moving the pump handle a few times. Should it sound like a wounded Seal? It has been sitting about 6 mths.

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 Yes they do sound like a wounded seal, even the new ones.That's the best description yet.

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Is the filter on the inner fender full?

Run a hose off the outlet nipple of the pump into a can and work the arm. See if it pumps gas out. Also a good place for the pressure gauge.

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Another idea...

I've read on here where cars that sat needed fuel poured into the overflow bungs to get the floats moving up and down maybe unsticking the fuel valves? If you get the float chambers full of fuel at least it would run for a little longer than ether. Maybe if you got it going and worked the throttle rod it would fix itself? Kinda like an "Italian tune up".

Good luck!

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So I have checked the manual fuel pump and it works great. I have checked everything from the fuel filter forward and everything is good. Nothing blocked and everything seems in good working order. Just seems like no gas getting to the fuel filter.  The car has sat for 6 mths and prior to that ran and started perfect, even when sitting for awhile. Where do I go from here? Is there a filter at the tank or in the tank? Do I need to drop it for the next step? Thanks.

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Try taking the gas cap off and see what it does. 

Pull the hose off the input of the filter and see if you can suck fuel up, or blow into it and listen for bubbling in the tank.

Edited by siteunseen

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Are the hoses in good condition? Some small cracks will let in air and make it where the pump isn't able to move fuel.

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I will try blowing air towards the gas tank and see what I hear. The engine compartment is like new, everything replaced or rebuild 2 yrs ago. Has about 300 miles on is since. I haven't done anything hose/fuel related from the engine compartment back to tank.

 "I've read on here where cars that sat needed fuel poured into the overflow bungs to get the floats moving up and down maybe unsticking the fuel valves? If you get the float chambers full of fuel at least it would run for a little longer than ether. "  Where are the overflow bungs /float chambers?

.

Edited by GregP
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1 hour ago, GregP said:

I will try blowing air towards the gas tank and see what I hear. The engine compartment is like new, everything replaced or rebuild 2 yrs ago. Has about 300 miles on is since. I haven't don anything hose/fuel related from the engine compartment back to tank.

 "I've read on here where cars that sat needed fuel poured into the overflow bungs to get the floats moving up and down maybe unsticking the fuel valves? If you get the float chambers full of fuel at least it would run for a little longer than ether. "  Where are the overflow bungs /float chambers?

 

.

Pour gas down through here and fill the float chambers. I call them chambers but they're float bowls too. When you get them full try sticking a wd-40 red straw down and see if you call feel the floats moving up and down.

20190822_163245.jpg

Edited by siteunseen
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@GregP

Clarifying my point here because it's bothering me. LOL

The fuel valves above the floats can and do get sticky/stuck after sitting. I've bought new ones, to me, that were. My thinking was if those valves aren't opening your fuel has hit a dead end. By filling those bowls the floats should raise and move the needles in close them off. BUT poking the floats with the straw should get them to bounce like a fishing bobber and move those needles. The floats are so close to the wall the straws movement will be minimal, maybe up and down a quarter inch?

Best of luck and please share the problem when you get it whipped. 

Cliff

 

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It's Running! After reading the last posts I disconnected the line to the fuel filter and blew some compressed air in to it going back to the gas tank. Heard the bubbling in the gas tank.

Next I filled both float chambers (I had to order a squeeze bottle that holds fuel and the tube went over the nipple perfectly. The bottle is used for filling RC cars). While I was at it, I filled the fuel filter since I had the line disconnected, figured it wouldn't hurt to help with the priming. I used my wd-40 plastic tube and pushed the floats. They bobbed up and down with no problems. Reconnected the fuel lines hoses and the car started up perfect and runs perfect!!! So I don't know if the floats were stuck and were freed up when adding the gas thru the nipple or if there was just an air pocket in the lines. 

Thanks everyone for the help and Cliff, great photo and descriptions. You made it real simple for me to follow.

Edited by GregP
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