Baffled by fuel problem in 1971 Fairlady/Z - can someone help?

Kerrigan

Well-Known Forum User
The car was running fine. Parked in garage for a week. Wouldn't start. No fuel getting to carbs. Thought it was original (1971) fuel pump, so replaced it and filter. Huffed back through gas line to tank and it "bubbles" fine with 1/2 tank in it now. Sucked gas into new filter with no effort. Watched camshaft turning while spinning engine. No electrical pump on these cars at the tank, just the mechanical on the engine.

Is there something inside the block, something to do with the pump arm, that could be broken?

The original pump sucks and spits gas out of the car.

Disconnected gas line at carbs and no gas at all when cranking.

Gas lines from metal one down on frame are all new; new clamps, etc. No leaking.

I'm totally baffled and could sure use some suggestions of what to look for next; thank you!
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
When you put the pump on did you make sure the operating arm went over the cam and then rested on it?

Is the rod inside the pump that pulls the diaphram clipped under the arm ok?

Split/holed diaphram?
 

Nigel Brook

Well-Known Forum User
Irrespective of you being able to blow down the line into the tank it could be debris/rust settling on the tank outlet especially if the tank has never been off/cleaned.
 

Kerrigan

Well-Known Forum User
Tank has probably never been off and at my advanced age, I'm not up to taking on the task. Unless I can find a good Z mechanic in the Portland Oregon area who can work on it, I guess it will just go back on jack stands and get covered up.

I've spent way too long, and too much money, chasing this problem already.

The wife says "if it won't run, get rid of it!!"
 

MaximG

Well-Known Forum User
Urm ok your getting fuel to the pump.
Are you getting fuel after the pump
Do you have fuel at the carbs.
Do you have fuel on the return from the carbs to the tank.
If all the above are yes.
Check the small filters at the unions going into the carbs or make sure the floats inside the float chambers are not stuck.
Check the Plugs to see if they are wet with fuel after turning over for a bit.
If they are wet then you have fuel but no spark.
 

Kerrigan

Well-Known Forum User
I get fuel at the filter if I suck on the line from the tank.

That's as far as it goes; the pump isn't pumping .. or sucking strong enough to pull it from the tank. These cars don't have an electric pump at the tank.

No fuel at the carbs.

Carbs are fine; just rebuilt last year by Z-Therapy ... new everything at that point.

Thinking the driving cam on the front of the camshaft is loose/getting ready to fall off/spinning or something ...

Going to pull the valve cover and see what's going on there ...

Plugs are dry.

I can disconnect the fuel line at the carbs and spin the engine to no avail ... no gas.

Spark is fine.

It was running great, sat in the garage for a couple of weeks, and wouldn't start. Sprayed a little ether in the air horn and it fired.

Gotta be a fuel problem ... somehow .... tank is full of fresh gas ...

This car is not easy to fix, that's for sure .... every problem has been a bear to resolve, taking a lot of time and money.

Gets old after a while ... like I am .... don't like crawling around under them any more ... or bending over the engine for hours at a time.

Wish there was a good Z mechanic in the Portland Oregon area. None in a city of over a million people ... so wierd.


Urm ok your getting fuel to the pump.
Are you getting fuel after the pump
Do you have fuel at the carbs.
Do you have fuel on the return from the carbs to the tank.
If all the above are yes.
Check the small filters at the unions going into the carbs or make sure the floats inside the float chambers are not stuck.
Check the Plugs to see if they are wet with fuel after turning over for a bit.
If they are wet then you have fuel but no spark.
 

Immunis

Forum User
I'll repeat the solution I made for the same issue when the fuel pump wouldn't prime on air:

'I had trouble priming the fuel pump on my 260Z after a long lay up and created a cheat method. I took apart a cheap bicycle pump and turned the valve around then pinned it in place. The bike pump now sucks rather than blows. Suction at the fuel line of one carb while blocking the fuel line at the other and I soon had the fuel where it needed to be.'

The issue with my carbs was in the needle values for the float chambers sticking, thus letting the fuel run down from the pump and out the carb and making the pump suck on air. New valves were got from zcarsource in Arizona.

Good luck with sorting it out.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Ok, if you are frustrated and about to give up put an electric pump on it. Sorted and enjoy!
 

jonbills

Membership Secretary
Site Administrator
You can sort this - it is very straight forward - just think it through. If you can suck fuel as far as the pump, but when you connect it it doesn't pump, then the pump isn't pumping. Either it's bust, or connected wrong, or the lever's not on the cam.
maybe you've had two problems - the original one you've fixed, but in your hunt for for it you've created another. like reconnecting the lines to the wrong side of the pump.
just a thought.
 

Zed-the-red

Well-Known Forum User
I get fuel at the filter if I suck on the line from the tank.

That's as far as it goes; the pump isn't pumping .. or sucking strong enough to pull it from the tank. These cars don't have an electric pump at the tank.

No fuel at the carbs.

Carbs are fine; just rebuilt last year by Z-Therapy ... new everything at that point.

Thinking the driving cam on the front of the camshaft is loose/getting ready to fall off/spinning or something ...

Going to pull the valve cover and see what's going on there ...

Plugs are dry.

I can disconnect the fuel line at the carbs and spin the engine to no avail ... no gas.

Spark is fine.

It was running great, sat in the garage for a couple of weeks, and wouldn't start. Sprayed a little ether in the air horn and it fired.

Gotta be a fuel problem ... somehow .... tank is full of fresh gas ...

This car is not easy to fix, that's for sure .... every problem has been a bear to resolve, taking a lot of time and money.

Gets old after a while ... like I am .... don't like crawling around under them any more ... or bending over the engine for hours at a time.

Wish there was a good Z mechanic in the Portland Oregon area. None in a city of over a million people ... so wierd.

Beautiful place Portland. Forgive my Limey humour.. But if you pay I will gladly fly over fix your car and come back....:rolleyes:
If you can suck gas through the large bore pipe then the tanks not the issue. Blowing back through the pipe would release the blockage and allow a little gas to be pumped through before the car starves as the debris settles in the tank. That's not the issue. When you replaced the pump did you also fit the spacer onto the back of the pump? Also check what the other guys have said re priming the pump {although I have never had to prime mine} and the connections to the pump.
Check also the braided hoses from the pump to make sure one has not collapsed internally they can get a bit weak with age and as the pump sucks it collapses the walls of the pipe which is no help at all to get the gas through.
You could try an electric pump mounted under the bonnet but ideally pumps like to push rather than pull....
I hope you get this sorted soon.. I am also in the advanced years. But still find a great deal of relaxation delving about and maintaining my Z. The relaxation is excellent.. the aches and pains the next day are no fun.. but worth every creak and groan when the Z fires up and we zoom off for a drive. Good luck.:cheers:
 

RJRACIN240

Forum User
Let me know if you are ready to sell it, have a friend transferring up to Oregon; think he will be ready for a fixer upper?
 

Kerrigan

Well-Known Forum User
Best of Class in Portland Roadster Show ... not a fixer upper for sure. Just has a *&^$# fuel problem ...

But thanks for asking!

Let me know if you are ready to sell it, have a friend transferring up to Oregon; think he will be ready for a fixer upper?
 

Kerrigan

Well-Known Forum User
I'll try your suggestions ... thanks!

Beautiful place Portland. Forgive my Limey humour.. But if you pay I will gladly fly over fix your car and come back....:rolleyes:
If you can suck gas through the large bore pipe then the tanks not the issue. Blowing back through the pipe would release the blockage and allow a little gas to be pumped through before the car starves as the debris settles in the tank. That's not the issue. When you replaced the pump did you also fit the spacer onto the back of the pump? Also check what the other guys have said re priming the pump {although I have never had to prime mine} and the connections to the pump.
Check also the braided hoses from the pump to make sure one has not collapsed internally they can get a bit weak with age and as the pump sucks it collapses the walls of the pipe which is no help at all to get the gas through.
You could try an electric pump mounted under the bonnet but ideally pumps like to push rather than pull....
I hope you get this sorted soon.. I am also in the advanced years. But still find a great deal of relaxation delving about and maintaining my Z. The relaxation is excellent.. the aches and pains the next day are no fun.. but worth every creak and groan when the Z fires up and we zoom off for a drive. Good luck.:cheers:
 
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