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| Engine runs fine for a while then quits http://forums.ctzcc.com/viewtopic.php?f=4&t=9755 |
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| Author: | jp260z [ Tue Apr 14, 2020 8:40 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
I wish my questions were more helpful John. I'm sure you'll get to the bottom of this soon, you've covered most of the possibilities it sounds like. I like Frank's question better though.  I wish I'd have thought of it! Yours is one of the nicest Z's I've ever seen. Jay |
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| Author: | johnnyZ [ Tue Apr 14, 2020 10:04 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Thanks Jay. I really do appreciate your feedback  . With all that's going on right now, its keeping me busy. I'm sure we'll get it figured out soon.And No Frank. You cannot have my car...…… Not yet anyway 
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| Author: | johnnyZ [ Fri Apr 17, 2020 4:11 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
With fingers crossed, here is an update. Yesterday, I pulled numerous vacuums on the tank using a hand operated cylinder attached to the fuel supply hose which connects to the bottom of the fuel filter. I have used this "pump" before to remove old brake fluid from master brake cylinders prior to installing and bleeding with fresh fluid. After pulling out a couple of pints of gas, I then blew back the line using compressed air. I again pulled vacuum on the line to get the line filled with gas and I could not detect any restrictions so I reconnected the line to the filter and tried to restart the engine. No good!  I was not getting gas again to the filter, so I disconnected the line from the filter to inlet of the recently new Delphi fuel pump and had my wife crank over the motor. And what do you know? No suction at the pump inlet.  I then replaced the "new" pump with a spare that I had and she started right up. So, to Frank's credit, I may have bought a faulty pump from MSA. However, I am wondering if the pump may have failed due to the blockage I think I was having at the fuel tank.  The good news is that I ran the car around town and again idling on the driveway for a full hour without any problems. I took it out again today, did some minor carburetor adjustments and she continue to runs really well. I plan to take a few more short runs, fill the tank, and hope (again) this is the last update.
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| Author: | HowardJ [ Fri Apr 17, 2020 4:56 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
I will keep my fingers and toes crossed and say a prayer to the Z godz for you! |
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| Author: | Frank T [ Fri Apr 17, 2020 6:30 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
  Diaphragms on new old stock pumps become brittle with age and can work for awhile but then rupture and refuse to pump anything. Or, one of the one-way valves might have stuck open or closed. At any rate, congratulations on isolating your problem and effectively trouble-shooting it; well done old boy. I like the idea that your prefect Z also has a perfect fuel tank, too. That's a very nice thing to do for your car. |
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| Author: | johnnyZ [ Fri Apr 17, 2020 9:07 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Thanks again guys for your moral support. This car issue (which is minor in the current grand scheme of things) was something that helped keep me busy, test my patience, kept me from bugging my wife, allowed me to work on my Z with my son, and kept us all in contact during this "crisis". It's gratifying to know that you have worked on something with some resolve and have the buddies around to help you get there. Thanks! |
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| Author: | Frank T [ Sat Apr 18, 2020 2:17 am ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Wait ~ you have buddies???
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| Author: | jp260z [ Sat Apr 18, 2020 10:44 am ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Congratulations on figuring out the problem. Also Thanks to Frank for suggesting the faulty fuel pump. Nothing more frustrating than a faulty new part. Grrr On the bright side you now have a well serviced fuel tank. Which is great for peace of mind. I'm glad you got her worked out, great job sticking to it John. Your Z is well worth it! Jay |
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| Author: | johnnyZ [ Mon Apr 20, 2020 1:15 pm ] | ||
| Post subject: | Re: Engine runs fine for a while then quits | ||
Jeeez this has become a long thread! But I thought I might share this update with you anyway. After replacing the new Delphi fuel pump with my spare after getting the car running again (still being cautious) I decided to take the new pump apart to see why it wasn't pumping. I must say that the pump seems well made to me, and looks very similar to the original mechanical fuel pumps originally supplied on the cars when new. Remember, I installed another "new pump" when I first started having the fuel starvation issues. Before I disassembled the pump, I tried sucking and blowing on the suction side of the pump, only to discover that I was able to suck air (and some fuel, UGH!) out of the pump suction connection.... Hmmm. After disassembling the new pump, I found a small sliver of metal which fell out of the top section of the pump (see picture attached). The pump, otherwise, was clean. After checking the operation of both of the little diaphragm check valves (one suction, one discharge) and checking the main "pumping" diaphragm, I reassembled the pump and was able detect proper suction and discharge "puffs" when operating the pump arm. The debris must have been in this pump from the beginning, as it could not have passed though the new fuel filter. I assume that it could very well have affected the operation of the new pump when I last had the fuel issue again. Regardless, I still believe there was an intermittent blockage at the tank suction which hopefully as been eliminated. Time will tell.
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| Author: | Frank T [ Mon Apr 20, 2020 9:32 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Yup! That would surely do it! |
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| Author: | jp260z [ Tue Apr 21, 2020 10:02 am ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Good troubleshooting John. I bet that piece of metal was preventing a valve from opening or closing and causing loss of pressure. You may have ended up with a useable spare pump now! Jay |
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| Author: | Frank T [ Tue Apr 21, 2020 1:16 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Or a repaired new one. Time to take 'er out and give her a day's test John. Say wheeen (Doc Holliday). |
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| Author: | HowardJ [ Tue Apr 21, 2020 2:53 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
Sooo... glad to hear that your Z's colonoscopy was a running success. LOL. Good job Dr. John. 
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| Author: | Paul [ Sat May 09, 2020 9:01 am ] |
| Post subject: | Re: Engine runs fine for a while then quits |
I know that scenario very well..........You think you have your problem solved so you go through all this work..........and then..........it ends up being some stupid little thing. 
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| Author: | johnnyZ [ Thu May 14, 2020 5:21 pm ] |
| Post subject: | Re: Engine runs fine for a while then quits |
After |
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