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Hi all , need your help again. 1978 280Z. The old gas tank was corroded and gummed up ( car sat for 4 years with gas in it ) I cleaned it out as good as I could,and it ran. However ,to unclog the return line in the tank,I had to break it loose in there. I really don't know what that did,but the car wouldn't run unless tank was basically full.After you burn 7-8 gallons it would start to bog down when you give it the gas like the tank was empty.Fill it up and it would be fine. I took the tank off my parts car , cleaned it out,( much better shape) and put it on.I filled it with gas and it ran fine. I had a cold start problem which ,thanks to JohnH240,was solved (turned out the thermotime and coolant temp.sensors were connected bakwards) It started on 1st crank on several very chilly mornings.NOW,monday morning while on my way to work,it started sputtering and died. I pulled fuel line at filter and it was clogged up. Shook it around and it started and ran o.k.I got a new filter, old one had a pretty good bit of trash ! Next morning , on my way to work, killed again and wouldn't start. I called in ,pulled car to shop (to get it on a rack) and drained tank. I changed the fuel filter again.(NAPA gold) No start. I burned up the starter (Remember those cold start crankings) I bought a new one and it cranks but no start. I pulled the line at the filter,no gas. I went (I know this sounds crazy but I was desperate) and bought a new fuel pump and put it on. Still no gas at the filter. I am getting no gas to the pump. I pulled the line off from the tank to the pump (at the pump) and I blew in it and I could hear the bubbles in the gas tank so I guess it's clear .Did I miss something ? Does anyone know where to go from here. Help....my wife had to bring me to school this morning.
 

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Put a fuel pressure gauge between the fuel filter and the top fuel rail. What is the pressure?

Remove both lines at the tank.

Get a 5 gallon gas can and put 3 gallons of fuel in it with 2 ounces of fuel injector cleaner and one ounce of fuel stabilizer. Hook a piece of hose up to the inlet of the pump and put the other end in the container.

Get a cheap plastic see through fuel filter, or a glass one with a replaceable element, and install it on the return hose. Run the output of the filter into the 5 gallon container. Since the return line is low pressure the plastic or see through filter should not explode.

Remove the fuel filter at the front of the car and hook the two fuel lines together, through the fuel pressure gauge, so that you bypass the filter and the fuel rail. Run the pump for about 30 minutes and watch for junk being collected at the filter on the return line.

What is the fuel pressure?

The cleaners should start to dislodge any crud in the lines within the 30 minutes. If no gas comes out the return line then the inlet to the pump has probably got plugged or the output fuel line is completely blocked. On some pumps the inlet fitting can be removed and the screen in the inlet can be cleaned.

Pour the fuel with cleaners in it into the gas tank.

Once you are sure the lines are ok, put the see through filter on the fuel pump inlet line and hook the vehicles gas tank back up. Run the pump for another 30 minuets and watch for crud coming from the tank through the filter to the pump. Since the input to the pump has no pressure on it you may choose to leave the see through filter in its place.

To run the fuel pump for this length of time use a battery charger to power it and you will also have an easy way to turn the pump on and off.

Reconnect the vehicles fuel filter and fuel rail, reconnect the fuel pump and start the engine.

What is the fuel pressure?

Wayne Monteath
Masham, Quebec.
 

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You will probably have to support the external container above the level of the pump, sort of like a gravity feed system.

The important thing is the use of a fuel pressure gauge.

Wayne Monteath
 

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My guess is that the fuel damper is blocked with crud that was loosened when you cleaned out the return lines. If it were totally blocked, the fuel pump couldn't suck fuel from the tank because of the back-pressure. Basically the air in the line downstream of the pump has nowhere to go so the pump can't prime itself. I'm not sure if the fuel damper can be back-flushed or not. Probably not, so it would have to be replaced. Just a theory.
 
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