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AMC 401 runs only on starter fluid

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wight4031 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wight4031 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/23/2022 at 11:11pm
The auto parts stores sell a generic carb rebuild kit that covers most typical carbs for about $40.  Has passable instructions, which along with youtube, can walk you through how to tear down and rebuild the carb.  I rebuilt a Holley 4bbl carb for my 304, helped a lot, but the engine was still prone to hot-flood.  Finally bit the bullet and swapped out to an Edelbrock 4bbl carb.  Course, it also helped that I replaced the factory 2bbl intake manifold that a PO had installed the 4bbl Holley on with an Edelbrock Performer 4bbl intake...

Censored PO's, go figure, I've learned not to take anything for granted with my 73 Commando.
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Jun/24/2022 at 5:25am
Best bet, Borrow  a spare carb that fits the engine.
Eliminate all easter egg hunts involving non fuel system parts.
If not try this.
Get a oil squirt can, enpty it and try gas instead of starter fluid.
Force the choke shut after it starts.

If the carb has gas in it it should run with the choke forced shut.






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Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/24/2022 at 8:54am
On an engine that had sat for extended periods of time, my old-school granddad, a mechanic since the 1920's, advised me to remove each spark plug and, with a pump oil can, put a "short stroke" shot of motor oil in each cylinder and then perform a "wet" compression test. Cranking the engine that way also puts a bit of oil on the cylinder walls, 

If the wet compression test shows acceptable numbers, then you can move on to the fuel system. As others have said, un-vaporized fuel doesn't ignite worth a Censored. Full stop.
Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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Heavy 488 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/24/2022 at 1:47pm
Have any 2 cycle fuel mixed for yard equipment? Use that for priming and playing with an engine that hasnt been fired for a while. Or just get a premixed can.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeebo76 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/24/2022 at 7:56pm
Thanks for the responses, everyone.  I'll try some 2 cycle fuel out of an oil squirter tomorrow and see if anything changes.  I'm ordering a carb rebuild kit tonight, and will tackle that once it comes in.

As a side note, I also re-timed it, and confirmed that my distributor is at least on the correct tooth for how the cap is laid out (#1 plug is pointing roughly "forward" on the cap relative to the engine) by trying other configurations and learning it wouldn't run any way other than the "correct" one.

I said in my last post that I'd have a compression tester today, but turns out it's not "today", it's "soon".


Edited by zeebo76 - Jun/24/2022 at 8:22pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeebo76 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/26/2022 at 11:08pm
Got the compression tester today.  The results are mostly encouraging, with a helping of "I expected that".

Cyl 1: 150
2: 143
3: 150
4: 145
5: 70
6: 150
7: 145
8: 150

There's definitely something going on with Cyl 5, I suspect stuck rings, so it's currently enjoying a SeaFoam bath.  Will see if the numbers improve tomorrow. If they don't, I'll pull the valve cover and check if anything's going on there.

Carb rebuild kit is on its way, it arrives tuesday.

On a more self-indulgent note, here's a picture of the truck itself:



Edited by zeebo76 - Jun/26/2022 at 11:10pm
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390rambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 390rambler Quote  Post ReplyReply Direct Link To This Post Posted: Jun/27/2022 at 7:10pm
Check the fuel pump. Make sure you have about 6psi.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote zeebo76 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/30/2022 at 2:38pm
Rebuilt the carb yesterday, and everything on it works fine now, even the accelerator pump.  Still won't run - it will ALMOST run, but the time it came closest to actually running on its own fuel it backfired out the carb at me and then lost spark. I have a loose connection somewhere.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Jun/30/2022 at 4:54pm
Fill the tank with starter fluid and run it. I mean, how much more can it cost than gasoline?Smile
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Kreep View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2022 at 9:10am
Make sure you have a good ground to the engine block.
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http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
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