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Posted: 9/16/2024 4:44:45 PM EST
[#1]
Quote HistoryQuoted: Are you using an electric pump? These things only need a few lbs of pressure, like 3-5. You could run that thing with just a gravity feed. Elevate the tank and syphon the fuel. That would rule out too much pressure. No, I'm using a standard mechanical fuel pump. |
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Posted: 9/16/2024 4:46:24 PM EST
[#2]
One question I have, there is what looks like a lower fuel port on the back side of the carb. It was originally covered with a small rubber cap, which had dry rotted and was no longer sealing. I stuck a bent piece of fuel line on there to keep it sealed, but is this some sort of fuel overflow/return on the carb itself?
 
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Posted: 9/16/2024 4:49:13 PM EST
[#3]
Vacuum port
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Posted: 9/16/2024 4:49:53 PM EST
[#4]
Quote HistoryQuoted: Vacuum port Ahhh....I think there are a couple on the carb. |
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Posted: 9/16/2024 6:19:10 PM EST
[#5]
Quote HistoryQuoted: Ahhh....I think there are a couple on the carb. Quote HistoryQuoted: Quoted: Vacuum port Ahhh....I think there are a couple on the carb. Vacuum port for the power brakes or PCV to be specific IIRC, which is no guarantee. It's been a while since I plumbed that old AIR system pollution crap. |
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Posted: 9/16/2024 6:21:52 PM EST
[#6]
Oddly enough, I went back out and cranked it again, and didn't seem to be leaking/overflowing this time. I didn't want to run it too long, need to go through the radiator and add some coolant. I also need to decide what I am going to do about the fuel tank, I still have no idea what condition its in. I'm going to try running by worthless Milwaukee M12 endoscope down the fill neck tomorrow, and see what condition its in.
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Posted: 9/16/2024 6:31:20 PM EST
[#7]
So did you get it running yet? Figure out the cam and distributor indexing and timing?
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Posted: 9/16/2024 7:03:37 PM EST
[#8]
Quote HistoryQuoted: Oddly enough, I went back out and cranked it again, and didn't seem to be leaking/overflowing this time. I didn't want to run it too long, need to go through the radiator and add some coolant. I also need to decide what I am going to do about the fuel tank, I still have no idea what condition its in. I'm going to try running by worthless Milwaukee M12 endoscope down the fill neck tomorrow, and see what condition its in. Iv've spent too much time cleaning tanks. It is pretty labor intensive and dirty. New tanks are surprisingly inexpensive. |
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Posted: 9/16/2024 7:56:17 PM EST
[#9]
Quote HistoryQuoted: It's usually the top of the tank that rusts, not the bottom. I'd suggest pulling it. I don't think you're going to see much through the filler neck. Iv've spent too much time cleaning tanks. It is pretty labor intensive and dirty. New tanks are surprisingly inexpensive. I actually have an extra tank put up in the shop, I'll pull it down and see what shape it's in. I'm keeping my fingers crossed that given how clean the carb looked, maybe the tank is in equally decent shape. |
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Posted: 9/17/2024 2:18:51 PM EST
[#10]
Quote HistoryQuoted: I actually have an extra tank put up in the shop, I'll pull it down and see what shape it's in. I'm keeping my fingers crossed that given how clean the carb looked, maybe the tank is in equally decent shape. I like the factory 20 gallon tanks. Extra capacity and they are poly so rust is never a concern. |
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Posted: 9/17/2024 2:29:53 PM EST
[#11]
Metal polish onto a q-tip chucked up in a drill. Polish the needle seat rinse and repeat.
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Posted: 9/17/2024 4:50:36 PM EST
[#12]
Quote HistoryQuoted: Metal polish onto a q-tip chucked up in a drill. Polish the needle seat rinse and repeat. I tried the old needle/seat, as well as the replacement assembly, no change. The last time I cranked it last night, it actually didn't seem to flood out the carb....but it did when I tried it again this morning. Good thing is, it cranked almost immediately and is still idling well...at least right up until the carb floods. |
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Posted: 9/17/2024 5:21:34 PM EST
[#13]
Buy a new carb and save yourself the hassle of the old one.
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Posted: 9/17/2024 5:32:48 PM EST
[#14]
Quote HistoryQuoted: Buy a new carb and save yourself the hassle of the old one. Lol, wut? If the fuel pressure is in fact too high, its going to be a problem regardless of which carb I use...new one included. |
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Posted: 9/17/2024 5:42:25 PM EST
[#15]
Quote HistoryQuoted: Lol, wut? If the fuel pressure is in fact too high, its going to be a problem regardless of which carb I use...new one included. If you are using a stock mechanical fuel pump and you have a flooding problem it isn't the fuel pump causing the flooding. |
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Posted: 9/17/2024 6:05:00 PM EST
[#16]
Quote HistoryQuoted: If you are using a stock mechanical fuel pump and you have a flooding problem it isn't the fuel pump causing the flooding. It is if its creating too much fuel pressure, more than the float & seat can seal off. The floats in this carb aren't that big, and don't provide a lot of mechanical leverage against the needle/seat to shut off fuel...wouldn't take much pressure to push past the needle/seat to flood the carb. I really need to try it just gravity feeding fuel to the carb, and see what happens. I also need to get an actual gauge on the fuel line to see exactly how much pressure is building, I just don't think I have a gauge that will read that low (I believe the spec for the Carter is around 2-5psi). |
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Posted: 9/17/2024 6:13:00 PM EST
[#17]
Quote HistoryQuoted: Lol, wut? If the fuel pressure is in fact too high, its going to be a problem regardless of which carb I use...new one included. Quote HistoryQuoted: Quoted: Buy a new carb and save yourself the hassle of the old one. Lol, wut? If the fuel pressure is in fact too high, its going to be a problem regardless of which carb I use...new one included. Yep, slap a Weber on it all call it good. |
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Posted: 9/17/2024 6:21:30 PM EST
[#18]
I doubt that the fuel pump is creating too much pressure. If anything the fuel filter or return line is plugged. More likely it's a float or needle and seat problem. They can be extremely temperamental.
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Posted: 9/17/2024 6:25:19 PM EST
[#19]
How much have you ran it? Is it possible you have over filled the tank, running your external tank? I imagine more fuel is returning than being consumed.
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Posted: 9/17/2024 7:14:33 PM EST
[#20]
Don’t be scared op!
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Posted: 9/17/2024 7:15:28 PM EST
[#21]
If anything the fuel filter or return line is plugged. More likely it's a float or needle and seat problem. They can be extremely temperamental. Haven't really considered the return line, I'll have to check it tomorrow. As far as the needle & seat go, while I admit it *could* be the issue, I just don't see it. I cleaned the original and bench tested it, shut off fine. Replaced it with a new needle and seat, doing the exact same thing. I honestly haven't been able to run it long, mainly because it doesn't take long for the carb to flood out. |
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Posted: 9/17/2024 7:23:41 PM EST
[#22]
Quote HistorySadomasochism. Why no 6-pack? |
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Posted: 9/18/2024 12:54:21 PM EST
[#23]
Update 9/18
I went ahead and pulled the tank, which wasn't as bad as I suspected...worst part are the hoses that are pretty much seized in place, but you have very little room to work to actually loosen them up. The two hoses going to the charcoal cannister/evap system(?) in the back were completely toasted, and most of the hose clamps were so rusted they simply fell off. Good thing is the fill neck and vent tube hoses are still good, they can easily be reused, but all other hoses will have to be replaced. Here's the tank...   ...and the sending unit.  There was definitely a decent amount of rust in the bottom, which should have cleaned out OK, except this was the bottom of the tank...   Yup, rusted through in multiple spots. Luckily, I have this sitting on a shelf in the barn....  
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Posted: 9/18/2024 1:54:12 PM EST
[#24]
Quote HistoryQuoted: Yep, slap a Weber on it all call it good. Webers require a fuel pressure regulator. Been there, done that. MC2100 > Weber |
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Posted: 9/18/2024 1:55:22 PM EST
[#25]
Quote HistoryQuoted: Update 9/18 I went ahead and pulled the tank, which wasn't as bad as I suspected...worst part are the hoses that are pretty much seized in place, but you have very little room to work to actually loosen them up. The two hoses going to the charcoal cannister/evap system(?) in the back were completely toasted, and most of the hose clamps were so rusted they simply fell off. Good thing is the fill neck and vent tube hoses are still good, they can easily be reused, but all other hoses will have to be replaced. Here's the tank... https://i.imgur.com/j9xsx0s.jpg https://i.imgur.com/4PvtUw1.jpg ...and the sending unit. https://i.imgur.com/Nyfmovg.jpg There was definitely a decent amount of rust in the bottom, which should have cleaned out OK, except this was the bottom of the tank... https://i.imgur.com/KRWALO2.jpg https://i.imgur.com/8VdPUgs.jpg Yup, rusted through in multiple spots. Luckily, I have this sitting on a shelf in the barn.... https://i.imgur.com/HT37doP.jpg https://i.imgur.com/ETEQ4vG.jpg Just slap some JB Weld on it and run it! |
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Posted: 9/18/2024 3:33:26 PM EST
[#26]
Quote HistoryQuoted: Just slap some JB Weld on it and run it! Lol, believe it or not, I spent more than a few minutes trying to figure out how I could repair it...but even if I didn't already have a spare tank, a new replacement tank is under $100 delivered. |
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Posted: 9/18/2024 6:19:53 PM EST
[#27]
Hey OP.....
I was looking through FB marketplace for some Jeep parts, saw this brand new carb for a 258 for $40. If you're interested, I'll see if it's still available. I'll have it sent to me, then send it off to you. Link to FB market place ad for 258 carburator. 
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Posted: 9/18/2024 6:22:12 PM EST
[#28]
Quote HistoryQuoted: Hey OP..... I was looking through FB marketplace for some Jeep parts, saw this brand new carb for a 258 for $40. If you're interested, I'll see if it's still available. I'll have it sent to me, then send it off to you. Link to FB market place ad for 258 carburator. https://scontent-sea1-1.xx.fbcdn.net/v/t45.5328-4/450966361_1471808493707498_5252579128290906589_n.jpg?stp=dst-jpg_s960x960&_nc_cat=105&ccb=1-7&_nc_sid=247b10&_nc_ohc=x3aeLM0UJr4Q7kNvgGebV5c&_nc_ht=scontent-sea1-1.xx&_nc_gid=Acm4TN9JSHE3Wdg2aROAdrU&oh=00_AYCOL4WXPkaMVBZ12J2QKAuLi3_t04qRLjBwtN3QabQrIg&oe=66F1273E Yes, please check!! |
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Posted: 9/18/2024 7:03:47 PM EST
[#29]
This thread reminds me of why I ditched the carb on my AMC 401 V8 in my 79 Cherokee.
I am running multi port fuel injection with full timing control. Built and tuned it all myself. OP, have you looked into doing a 4.0 head swap? It is a popular swap for the old 258's. Go to the junkyard and get a 4.0 head and intake/fuel injection stuff and swap it over to the 258. 91-95 are the best years to use. |
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Posted: 9/18/2024 8:18:12 PM EST
[#30]
OP, have you looked into doing a 4.0 head swap? It is a popular swap for the old 258's. Go to the junkyard and get a 4.0 head and intake/fuel injection stuff and swap it over to the 258. 91-95 are the best years to use. The amount of work necessary in adding fuel injection via a 4.0L head swap isn't exactly plug and play....there's an assload of work. Head, wiring, adding crank sensor (either via harmonic damper or to the bell housing), and that's just the major stuff...still a decent amount of minor tweaking involved as well. Before I even remotely considered that, I would simply do a complete 4.0L swap with an AX15 and adapter plate for the D300. |
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Posted: 9/19/2024 6:55:01 AM EST
[#31]
Quote HistoryQuoted: The amount of work necessary in adding fuel injection via a 4.0L head swap isn't exactly plug and play....there's an assload of work. Head, wiring, adding crank sensor (either via harmonic damper or to the bell housing), and that's just the major stuff...still a decent amount of minor tweaking involved as well. Before I even remotely considered that, I would simply do a complete 4.0L swap with an AX15 and adapter plate for the D300. You could also do a swap to throttle body fuel injection. All that would be is a adapter plate to your current intake, rig up the throttle cable and air filter, add a few sensors, electric fuel pump and you are good to go. I am sure there are places that make bolt on kits if you do not want to tune it yourself. The factory distributor can be modified to work with it. I had TBI on my 401 for a couple years before I switch to multi port. I started out with the factory distributor I modded, but then later switched to a modded HEI distributor. No crank sensor required for TBI. |
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Posted: 9/19/2024 7:02:55 AM EST
[#32]
My last and I promise it's my "last" 258 had carb issues.
It was all resolved with a 75.00 Amazon China carb. Thing ran great after that. |
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Posted: 9/19/2024 11:16:15 AM EST
[#33]
Well, I may have solved the carb issue. ***fingers crossed***
Started looking through things, and checked the return line off the filter going back to the tank....completely clogged. Traced the soft line, found this...  Attached File Attached FileNot sure what the previous owner was going for, but the kink in the hose completely blocked off all fuel going back to the tank....which meant all flow was going to the carb. Of course, the needle/seat couldn't keep up, hence the flooding. Ran a new kink-free hose, everything seems to be fine now. I may still need to adjust the float level, but it cranks easily, idles smoothly, and seems to rev without any hesitation. All it needs now is the tank replaced, coolant added, and i should be able to do a road test. I did hook up a gallon jug to the return line, and was very surprised by the amount of fuel bypassed around the carb. I probably ran it for less than a couple minutes, and there was at least a quart or so of fuel in the jug. |
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Posted: 9/20/2024 6:58:41 AM EST
[#34]
Yea the pump has more flow than is needed. There will be lots of return at idle as you are using barely any fuel.
At full throttle full load, there might be very little fuel return. But there still should be a little, otherwise the pump is too small and you run the risk of running out of fuel. I remember that happening with my old carb on my 401. I had a universal electric pump that only made a few psi. It worked fine 99% of the time. But if I hammered on it and all 4 barrels were open, it would suck the float bowls dry faster than the pump could fill them up. If I hammered it from a stop and ran it out to around 4k rpm before shifting, I would run out of fuel going from 3rd to 4th. And this is on a granny gear first gear transmission where you start out in 2nd for normal driving. |
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Posted: 9/20/2024 7:10:04 AM EST
[#35]
Now, about that recurring valve cover leak and the blow-by oil vapor...
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Posted: 9/20/2024 2:48:09 PM EST
[#36]
Quote HistoryQuoted: Now, about that recurring valve cover leak and the blow-by oil vapor... Thats actually funny after owning a Heep for 30 years |
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Posted: 9/20/2024 5:11:45 PM EST
[#37]
Once I get the replacement tank installed, I have to figure out hoses to the roll-over valve(?) and evap cannister...the lines to the roll-over valve were almost completely dry rotted. Once that is all sorted, I can get the drivers seat bolted back down and start driving it around.
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Posted: 9/20/2024 10:52:51 PM EST
[#38]
Quote HistoryQuoted: Once I get the replacement tank installed, I have to figure out hoses to the roll-over valve(?) and evap cannister...the lines to the roll-over valve were almost completely dry rotted. Once that is all sorted, I can get the drivers seat bolted back down and start driving it around. Thats bad ass. OP,throw some tools in that bitch. You will need them while you do your shakedown(for the next 20 years). I love Jeeps! |
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Posted: 9/21/2024 8:18:36 AM EST
[#39]
speaking of which- mine broke down yesterday on the way home. turns out it's a 2 part issue- the brain box checked out (old duraspark box) and the clear fuel fuel filter was "gulping" air from the line back to the tank. rpms kept dropping off, and the bucking/chugging was severe enough that I was genuinely concerned about the jeep spitting out the rear driveshaft.
found a place to pull over and made a call to have a spare brain box and tools brought to me. moral- CARRY SOME FOOKING SPARE PARTS and TOOLS to R&R. a 50 cal box is going unddr the hood, pass fender, along with spare parts. |
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Posted: 9/21/2024 8:57:36 AM EST
[#40]
Motivational pic for the op!
 So much jeep, so little time! |
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Posted: 9/21/2024 9:12:15 AM EST
[#41]
On my 258 AMC/Jeep, I tossed the Carter s far as I could.
I installed a Motorcraft 2150 from a Ford and it's been perfect for 25 years now. I've never had a carb as reliable on anything in my 65 yrs. Yes, I still own the Jeep. And do yourself a favor and install an HEI converted distributor. 2 wires and you're done. Trust me! |
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Posted: 9/21/2024 5:48:44 PM EST
[#42]
HEI conversion is the next project, once I get it actually driving down the road.
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Posted: 9/21/2024 5:59:42 PM EST
[#43]
Double tap.
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Posted: 9/26/2024 5:36:03 PM EST
[#44]
Update 9/26
Haven't had much time lately to work on the Jeep, but messed around a little with the replacement tank today. The inside of the tank looks great, absolutely no rust, but there is a little bit of old fuel varnish in the low parts of the tank. Any suggestions of a solution to use to try and clean the varnish out? Not sure I can spray enough brake clean in the bottom to brake it up, at least to reach all the spots, so I'll need to soak the bottom of the tank. It won't need much, just enough to cover the bottom. You can see a little bit of it in the pics...    Also, any reason not to go ahead and paint/cover the external of the tank with bed liner material? I have a few extra cans of it, seems like it might be some cheap insurance against future rusting (at least from water leaking in between the tank and the holding bracket/shield. |
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Posted: 9/26/2024 5:49:27 PM EST
[#45]
Have you got a bit of Acetone to try? If it works a qrt. isn't that much. Just don't smoke or make any sparks around the tank. Lacquer thinner may also work.
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Posted: 9/26/2024 5:54:48 PM EST
[#46]
Gasoline is a good mild solvent that I guarantee for safe use in that application.
 Sometimes tanks are a snug fit. If you paint it with bedliner you may have trouble getting it back in. |
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Posted: 9/26/2024 6:43:25 PM EST
[#47]
I pulled the sending unit, it's I'm really good shape....but what is this triangle piece hanging down with wire wrapped around it?
 Attached File Attached File Attached File Attached File |
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Posted: 9/27/2024 12:09:31 AM EST
[#48]
Looks like the potentiometer for your spending unit.
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Posted: 9/27/2024 2:33:25 AM EST
[#49]
I can't imagine it's supposed to be hanging down like that...
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Posted: 9/27/2024 6:29:00 AM EST
[#50]
You will need replace the sending unit.
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