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Engine runs fine for a while then quits
http://forums.ctzcc.com/viewtopic.php?f=4&t=9755		 Page 2 of 8
Author:  jp260z [ Mon Mar 16, 2020 7:30 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Great news John! Poor Mike though. I'm guessing next time he's wrestling a tank out of an old Z he will be on the passenger side instead. I'm glad you found a good place to have the work done, and that everything is in such good shape under there, that's terrific.

You never know with a Datsun, the hidden rust can be surprising sometimes. I'm glad it all looks good!
Author:  Frank T [ Mon Mar 16, 2020 7:39 pm ]
Post subject:  Re: Engine runs fine for a while then quits
I would take that to Jim Kinsella when it's been etched and sealed and have him paint it for you.

Karl makes a good point; I had forgotten you had a previous issue with high rpm flattening. You experimented a lot on that. If there was any fuel restriction coming from the tank, that might have caused or contributed to it.

Did you examine all your fuel lines btwn the tank and the pump? if any of them kink or collapse under 'vacuum' (no such thing, scientifically; it's just a difference in air pressure), that would certainly restrict fuel flow to the business end of your car. Remember an empty fuel filter bowl was our first suspicion?
Author:  johnnyZ [ Tue Mar 17, 2020 10:47 am ]
Post subject:  Re: Engine runs fine for a while then quits
Yes, I did check all the fuel lines. All of the lines from the engine bay to the tank are steel lines with rubber connecting hoses at each end which I believe is a good design. This week I will give the underside of the car in the tank area a thorough inspection and cleaning including inspecting all of the hoses back there. Initial inspection looked good, and again, the tank never seemed to experience a "vacuum" condition.

I really think there was something blocking the tank fuel pick-up tube.

We shall see. :roll:
Author:  HowardJ [ Tue Mar 17, 2020 12:15 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Hi John,

My 2 1/2 cents worth... Would I be correct to assume that the exhaust system on the car has NOT been moved or modified (bringing heat closer to the fuel)? Also fuel lines NOT rerouted or inadvertently placed near exhaust or EGR? (Boiling/vaporizing fuel- alias "vapor lock" usually occurring during hot summer days). Depending on the type of fuel pump (mechanical vs. electric) maybe: a rigid/dried diaphragm if it's the original; a torn/cracked diaphragm or maybe a cracked gasket allowing an air suction leak?

Can the fuel system be INTENTIONALLY plugged from maybe the carbs on back (air vents, air cleaner lines, filler neck, etc.) and then pressurized to test for leaks? Does the pickup tube have a "sock" or screen on it that might have or sometimes collapses? I'm sorry I don't have more to add to the knowledge pot.

Good luck and prayerZ on definitively finding the solution needed.

Howie
Author:  Frank T [ Tue Mar 17, 2020 12:22 pm ]
Post subject:  Re: Engine runs fine for a while then quits
When we were teens we used to secretly stuff potatoes up our buddy's exhaust pipes and then cruise around with them. When we went fast enough the blocked exhaust backed up into the combustion chambers and the car stalled.

We would all pull over together, act surprised and concerned, open the hood and offer to let our "mechanic" (17 years old) trouble-shoot the problem. We told the driver to sit at the wheel (so he couldn't see what we were doing) and pretend to fiddle around with stuff under the hood long enough for the back pressure to leak down to zero. Then we'd all stand back and have him turn the key, at which time the engine would start back up.

Cheering, we closed his hood and raced back to our cars to repeat the procedure several more times that night.

At the end of the night we took him around to the back of the car and pulled the potato out with a coat hanger, explaining what we had done. He and his girlfriend were in on the joke for the next cruise, when it was some other newbie's turn. 8)
Author:  HowardJ [ Tue Mar 17, 2020 12:32 pm ]
Post subject:  Re: Engine runs fine for a while then quits
:twisted: :mrgreen: :thumbs_up:
Author:  HowardJ [ Tue Mar 17, 2020 12:44 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Frank brings up a good point with his potato story. Exhaust restrictions. Might one or even two collapsed muffler baffles cause the engine to cut out? Not restart? Then "unblock" when it cools down? Questionable. Prevent fuel from entering float bowls? Probably not. :roll: :wink: :thumbs_down:
Author:  johnnyZ [ Tue Mar 17, 2020 3:06 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Hi Howie!

I checked for potatoes, ….none to be found! :P

Frank's story brought back a not too distant memory of an experience I had when a potato "projectile" actually shot out of the tailpipe of a nice red 240Z formally owned by a guy that asked me to help him find out why his car wouldn't start. Somebody had sabotaged his car with a potato in the tailpipe and sugar in his gas tank! :shock:

Hmmm, I wonder if my gas tastes sweet? :wink:
Author:  Frank T [ Tue Mar 17, 2020 6:02 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Right ~ the potatoes wouldn't work on any of the big V8s; they'd just get blown right out. We learned that on Bill Kauffman's SS 396 when both potatoes came flying back at us.
Author:  HowardJ [ Tue Mar 17, 2020 8:05 pm ]
Post subject:  Re: Engine runs fine for a while then quits
Spuddy Buddies! :thumbs_up: :mrgreen: 8) :D
Author:  Frank T [ Wed Mar 18, 2020 1:37 am ]
Post subject:  Re: Engine runs fine for a while then quits
:thumbs_up: :lol: :thumbs_up:

LoL!
Author:  johnnyZ [ Thu Mar 19, 2020 9:21 am ]
Post subject:  Re: Engine runs fine for a while then quits
2:37AM??? Frank, Do you ever sleep??? :roll:

While i'm waiting for my gas tank, I figured I might as well check the rear brakes while the rear end of the Z is on jack stands and grease the prop shaft. I just installed new front pads a couple of months ago. Rear shoes don't wear that much on these cars.
Author:  Frank T [ Thu Mar 19, 2020 11:48 am ]
Post subject:  Re: Engine runs fine for a while then quits
Yessir, I sleep from September when the humidity breaks and my nightmares stop, until spring when the temperature rises and all my dead buddies return to my dreams.
Just one of the prices of freedom for small struggling Republics.
Author:  HowardJ [ Fri Mar 20, 2020 9:11 am ]
Post subject:  Re: Engine runs fine for a while then quits
Semper Fi , bro.
Author:  Paul [ Fri Mar 20, 2020 9:15 am ]
Post subject:  Re: Engine runs fine for a while then quits
Make sure the return line and breather line are clear as well, also replace the rubber hoses with the hi-grade rubber that doesn't dissolve with Ethanol. I bought some myself from rock auto.
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