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Posted: 9/16/2024 5:44:45 PM EDT
[#1]
Quote HistoryOriginally Posted By ARHank: 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 5:46:24 PM EDT
[#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 5:49:13 PM EDT
[#3]
Vacuum port
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Posted: 9/16/2024 5:49:53 PM EDT
[#4]
Quote HistoryOriginally Posted By bluesx: Vacuum port Ahhh....I think there are a couple on the carb. |
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MD, USA
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Posted: 9/16/2024 7:19:10 PM EDT
[Last Edit: Ranxerox911]
[#5]
Quote HistoryOriginally Posted By Jason280: Ahhh....I think there are a couple on the carb. Quote HistoryOriginally Posted By Jason280: Originally Posted By bluesx: 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 7:21:52 PM EDT
[#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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MD, USA
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Posted: 9/16/2024 7:31:20 PM EDT
[Last Edit: Ranxerox911]
[#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 8:03:37 PM EDT
[#8]
Quote HistoryOriginally Posted By Jason280: 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 8:56:17 PM EDT
[#9]
Quote HistoryOriginally Posted By ARHank: 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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USA
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Posted: 9/17/2024 3:18:51 PM EDT
[#10]
Quote HistoryOriginally Posted By Jason280: 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 3:29:53 PM EDT
[#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 5:50:36 PM EDT
[#12]
Quote HistoryOriginally Posted By lowcountry: 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 6:21:34 PM EDT
[#13]
Buy a new carb and save yourself the hassle of the old one.
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Posted: 9/17/2024 6:32:48 PM EDT
[#14]
Quote HistoryOriginally Posted By DamascusKnifemaker: 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 6:42:25 PM EDT
[#15]
Quote HistoryOriginally Posted By Jason280: 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 7:05:00 PM EDT
[#16]
Quote HistoryOriginally Posted By DamascusKnifemaker: 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 7:13:00 PM EDT
[#17]
Quote HistoryOriginally Posted By Jason280: 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 HistoryOriginally Posted By Jason280: Originally Posted By DamascusKnifemaker: 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 7:21:30 PM EDT
[#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 7:25:19 PM EDT
[#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 8:14:33 PM EDT
[#20]
Don’t be scared op!
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Posted: 9/17/2024 8:15:28 PM EDT
[#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 8:23:41 PM EDT
[#22]
Quote HistoryOriginally Posted By 71jeepcj6: Don't be scared op! https://www.ar15.com/media/mediaFiles/485930/IMG_3838-3325196.jpg |
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Posted: Yesterday 1:54:21 PM EDT
[#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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USA
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Posted: Yesterday 2:54:12 PM EDT
[#24]
Quote HistoryOriginally Posted By 71jeepcj6: 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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USA
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Posted: Yesterday 2:55:22 PM EDT
[#25]
Quote HistoryOriginally Posted By Jason280: 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: Yesterday 4:33:26 PM EDT
[#26]
Quote HistoryOriginally Posted By wm69: 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: Yesterday 7:19:53 PM EDT
[#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: Yesterday 7:22:12 PM EDT
[#28]
Quote HistoryOriginally Posted By IdahoPCCinc: 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: Yesterday 8:03:47 PM EDT
[#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: Yesterday 9:18:12 PM EDT
[#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: Today 7:55:01 AM EDT
[#31]
Quote HistoryOriginally Posted By Jason280: 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: Today 8:02:55 AM EDT
[#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: Today 12:16:15 PM EDT
[#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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