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PostPosted: Fri Mar 13, 2020 7:44 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 682
Location: Ansonia, CT
Some of you may know that I had a bit of engine trouble during our little fun run this past Monday. Frank T and his lovely wife were following my lovely wife and I in our beloved Z's on RT 34 W just shy of the I84 crossover when my engine just sputtered and completely died. I had enough momentum to hang a left into a mulch company's lot where after much fiddling and head scratching I reluctantly called AAA for a flatbed ride home. This turns out to be only the second time in the car's 49 year history that it was flat-bedded home.

So, I have already replaced the coil, points, condenser and ballast resistor. The plugs looked fine. I then focused on the fuel system as it seems that there was little fuel reaching the carbs. I blew back the gas suction and return lines with compressed air and could hear the gas bubbling in the tank so I knew the lines were clear. I then ended up replacing the gas filter and my mechanical fuel pump with another Delphi OEM mechanical fuel pump purchased from MSA.

Hot digity! She started right up and seemed to run great. :thumbs_up: I took her out for a test ride and put on about 6 miles. After returning home, I left the Z running for a bit as the last time I thought I fixed the issue, she quit on the driveway while idling. She would not restart then and wouldn't you know it, the same thing happened again today! :roll: It would not start up at all. :thumbs_down: I verified that all plugs are getting spark so I still think I'm having a fuel issue.

I removed the rear carb float cover to find NO GAS in the bowl. Hmmm! :? I can blow though the float cover gas inlet just fine, and the float seems to shut the fuel off when lifted up. I'll check the front carb tomorrow to see if it is also dry. If it is, the only thing I can think of is that there is a restriction somewhere in the fuel system preventing my new pump and filter from delivering gas. I think this could possibly be caused by sediment in the tank, a pinched gas hose somewhere or a maybe a Leprechaun in the tank! Hey! I'm opened to all theories here fellas!

Well, tomorrow is another day. I'll keep you posted.

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John Kish
1971 240Z original owner


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PostPosted: Sat Mar 14, 2020 8:35 am 
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Hey John!

I'm sorry to hear about your troubleZ. I'm sure you are having a fuel issue and fortunately they are pretty easy to solve.

My first move with a no start condition is always to shoot a bit of ether in the carb(s) and crank it over. If it starts briefly then quits it's a fuel problem. If not it's a spark/compression problem. Easy way to zero in on the system that requires attention.

A couple troubleshooting approaches for you;

Connect the inlet of your fuel pump to a small Jerry can filled with fresh gas (you may need to pre-prime the fuel hose, also helps to gravity feed the pump by positioning the can higher than the pump....although once she's running it won't matter) and see if she starts and runs easily. This would indicate a problem in the tank or supply lines (you may have a piece of rust/junk in the tank that is floating and occasionally blocking the fuel pickup inside the tank) - I've actually seen this happen before.

I'd also confirm that the fuel return line isn't blocked either, as that will cause issues.

I don't believe you mentioned whether or not you confirmed if the fuel rail (pump to carburetors) is clear. Blow compressed air through those as well.

When you checked your float Chambers, did you confirm proper operation of the needle/seat assembly in the float lids. If even one of those is stuck closed (or blocked) it will make the car not want to start as only three cylinders are receiving fuel.

I also think it's worth verifying that the Venturi pistons are both moving freely in the domes. I'm sure they are but in the off chance one of them is hung up in the down position the needle will be cutting off fuel supply at the nozzle. Easy thing to confirm.

Hope this helps John.

Good luck with her!

Jay


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PostPosted: Sat Mar 14, 2020 2:53 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
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Location: Ansonia, CT
Thanks for your input Jay! Your advice was very much appreciated and most of your suggestions have already been implemented. :thumbs_up:

I am convinced that I am experiencing a fuel starvation issue. Both carb bowls were empty as was the fuel filter when the car died again after a prolonged run up on my driveway this morning. I have verified that all fuel lines are clear including the suction and return lines on the "fuel rail" as well as the little "flow guide valve" on the left inner fender and the "air supply" line which is connected to the fuel tank vapor reservoir allowing make up air into the tank preventing a tank vacuum as the tank empties.

Next step is to remove, inspect and clean the tank. I have siphoned out most of the gas. I won't try to remove the old tank drain plug which I would fear may lead to other issues as it has never been removed before. I am betting that there is a piece of rust or some foreign matter blocking the suction (outlet) line on the tank as you have suggested. Not a "fun Job" at my age, but Z season is approaching fast! :wink:

More to come!

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John Kish
1971 240Z original owner


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PostPosted: Sat Mar 14, 2020 4:43 pm 
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Good luck John. If the tank is original then you are sure to find some junk in there.

Truthfully that isn't a fun job at any age. When I removed the tank on my 260z (the second time) I found a bad strap too. I looked for replacements which I was unable to find, but they were very easy to reproduce as it turned out. Flat stock and some time forming, cutting and painting is all it took.

I'm anxious to hear how you make out! :thumbs_up:

Jay


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PostPosted: Sat Mar 14, 2020 10:35 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
The last time I removed a fuel tank I took a real bath. :roll:

You are narrowing down the probabilities to a clogged fuel tank pickup filter (even tho you air-hosed it in reverse) or a possible collapsing old rubber fuel line somewhere btwn the tank and the pump.

As Uncle Phil once learned, a blocked fuel tank air vent can cause fuel starvation; the pump lowers the fuel level to the point that the vacuum on either side of the fuel supply is equal, so the fuel stops flowing. His tank also collapsed from that, causing a large dent in the bottom. Phil thought his son had run over something with the car, the dent was that large.

Phil also got a loud WHOOSH when he opened the fuel filler cap as air rushed in to refill the tank. He said the vacuum was so strong he had to use an oil wrench to turn the cap off. If your car runs perfectly with the filler cap open, that is 99.99% likely your problem.

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PostPosted: Sun Mar 15, 2020 7:53 am 
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That's a great tip Frank. And another easy troubleshooting method.......which is why Datsuns are so fun to work on I think.

I had to replace tank in the late 1990s.....wasn't worth saving. The amount of rust in there was unbelievable......like it had been filled with salt water. Also full of holes.

Of course back then I was able to get an NOS tank for the "bargain" price of nearly $500. It was the last one in North America in Nissan's inventory I was told. Totally worth it in the end for a clean fuel supply and a good running car.

I think the only options now if it's as bad as that are sending it off to a fuel tank restoration company or having one custom made.

Jay


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PostPosted: Sun Mar 15, 2020 1:38 pm 
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Location: CT
Racing collapsible fuel cells are available in various custom box sizes, but they are very pricey and many interfere with the spare wheel well.

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PostPosted: Sun Mar 15, 2020 2:51 pm 
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Joined: Sat Feb 01, 2014 9:21 am
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Location: Somers CT
Possible this was your problem before with the lag at higher rpm's ?

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W.Karl Walton
Somers CT



75' - 280Z - HLS30203249 - #304 Gold Metallic (stockish)
96' - 300zx TT - JN1CZ24d3TX960293 - Black on Black (enhanced)


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PostPosted: Sun Mar 15, 2020 3:02 pm 
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Location: Ansonia, CT
Well, My son Mike and I wrestled the fuel tank out of the Z this morning. :thumbs_up:

After draining the last bit of gas out of the tank, initial inspection of the tank while peeking though the fill neck revealed a small about of rust scale on the tank bottom and peeking over the baffle, a small patch of rust scale on the thinner, drivers side of the tank side wall. The majority of the tank looks good inside but I can't see well past the baffle which separates the tank down the middle front to back. I can see the float and sending unit which looks good, but can't really see the suction pick-up on the other side of the baffle. I may be pulling the sending unit to see if I can see the driver's side of the tank better looking over the baffle, which is where the suction tube is located.

I may have the tank sent out or try to flush out and seal myself. Not sure which way to go yet. :?


More later.

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John Kish
1971 240Z original owner


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PostPosted: Sun Mar 15, 2020 5:55 pm 
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Good luck John, thanks for the update.

I've never sealed one myself, but I've heard the sealants can fail and clog the lines up. Might be worth pricing a professional refinish just to see what the cost is?

Jay


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PostPosted: Sun Mar 15, 2020 7:50 pm 
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Location: Ansonia, CT
Thanks Jay.

I've heard the same thing about sealers. Tomorrow I'm taking the tank to a professional who Vinny Bedini recommended.

Oh, and he is still looking to sell that nice 260Z :wink:

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John Kish
1971 240Z original owner


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PostPosted: Mon Mar 16, 2020 7:40 am 
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Good idea John.

Great to know that he still has it. Hope it will still be there when I've recovered from building this house, still a few major expenses to clear though so I'm out for now. It's tough being a grown up haha

Jay


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PostPosted: Mon Mar 16, 2020 9:33 am 
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Location: Ansonia, CT
Jay,

I can relate!

I've been there 40 years ago. :wink:

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John Kish
1971 240Z original owner


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PostPosted: Mon Mar 16, 2020 1:24 pm 
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Location: CT
["It's tough being a grown up haha"]
I don't wanna grow up. I will never get old.

John, back-blow all the hoses which connected to your fuel tank (there should be about 40 of them if I remember correctly :roll: ). Sometimes dirt daubers and other insects build mud nests in them which block them off. If any of your vent hoses are blocked, that will cause the problem you describe. And yes, pull the sender unit and the pickup filter and take this opportunity to change them both out. New straps too, if you need them. They are made of a different metal than the tank and are constantly exposed to wet, so corrosion btwn the tank and the straps is common. You might even paint everything before putting it all back together.

Did you find you had a few gallons of fuel left after you 'drained' the tank? I did. Had a Z up on a lift, drained it for 20 minutes then cut it loose to drop it. Standing roughly underneath it to keep it from falling, I took a real shower when the tank tipped backward and about 3 gallons of fuel found all those open vent holes. :?

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PostPosted: Mon Mar 16, 2020 5:12 pm 
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Location: Ansonia, CT
Thanks Frank.

Yes, I had blown back every line and all were clear. There are no open-ended fuel or vent hoses anywhere on my system other than what connects to the air filter (called and air supply line) which is terminated "inside" the filter. Also. the old Z's do not have any in-tank filters, at least my Z doesn't. I'm sure I wasn't pulling a vacuum in the tank anyway as the car became fuel starved on my driveway with fill cap removed the last time I ran it.

My tank straps are in excellent condition as back in 1985 I had removed the tank and straps, cleaned and painted all the hardware. Since that time, the car rarely saw any bad weather and was always garaged. In fact, I was surprised at just how good everything looked under the car in the area where the tank sits. I will probably re-clean and touch up the area now that I am waiting for the tank to come back from Port Chester Auto Radiator (and gas tanks). I dropped it off this afternoon at their shop. Rick Piper is the owner and seems to be a straight up guy.

Ha! :lol: Mike, my son got the gas bath yesterday as he was on the driver side while we wrestled the tank out of the car. That stupid (now open) vent tube on the "shallow" end of the tank was just low enough to spill the little remaining gas on his leg. Glad he's not a smoker! :shock: Rick at PCAR told me the tank should be ready in 2 weeks.


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John Kish
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