Question: Swapped 350 into CJ7, runs fine for 30 mins, then stalls when I come to sto - JeepForum.com
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Unread 09-01-2011, 01:32 PM   #1
Big_Pete1999
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Updated*Question: Swapped 350 into CJ7, runs fine for 30 mins, then stalls when idle.

I have my 1983 CJ7 with Chevy 350 engine swap done, and have been driving it to and from school when I can't use my wife's car cause obviously the jeep gets horrible gas mileage vs a honda civic.

I also need to add that when I state things with obvious answers such as checking spark plugs, please understand that to do this, I'll have to drive my jeep somewhere to do it, as my HOA has told me that if I even think about lifting the hood of my jeep 1 more time, they are gonna start fining me.
I also bought the engine already rebuilt (few thousand ago) and pulled from a 1970 Chevy truck. This is pertinent when it comes to my 3rd question and to why I'm not sure what to do.

A few questions....
I notice that when I drive to places that are 10+ miles away, or about 20-30 minutes, the jeep runs perfectly fine. BUT (there's always a but), when I get done doing whatever it is I'm doing (ex. getting tile, going to class, etc...) when I start up my jeep, it starts ok, but when I get to driving, it stalls each time I come to a complete stop, unless I lightly hit the gas to keep revs up to barely above normal idle.

This never use to happen, and has recently started happening. There are a few things that I think might have caused this, but I'm not sure, as some of them have been fixed, yet it still happens (although not 100% of the time anymore, only about 50% of the time).

#1. My tranny (sm465) had 2nd gear out. Naturally, that tranny has a granny gear, so I never launched in 1st anyways. This left me starting in 3rd and essentially having a 2 speed transmission. I had to give it gas and slip clutch to start in 3rd. I was thinking that maybe I gunked up the plugs etc cause of the extra gas, and over time, that's why it started happening (remember, it didn't always happen, only after a month or so of driving). I have since got the tranny rebuilt, and have noticed that after a few weeks of driving, the occurrence has decreased, so maybe I need to pull the plugs and replace?

#2. My PCV & Breather are on the same freaking valve cover. My passenger side has PCV in back, breather in front. The Drivers side has the grommet for the PCV in the front, but instead of the PCV valve, it has a wine bottle cork to plug it. Obviously this is wrong and needs to be fixed, but could this be aiding my stalling symptoms? I'm gonna have to either get a long hose to re-rout the pcv to the drivers front, or swap the valve covers. The only reason why I'm saying possibly swap the valve covers so pcv is on drivers, and I can put breather on passenger side is cause I tried to pull the cork out, but it broke, and I don't want it to fall into the head, so I'm probably gonna have to pull the valve cover off anyways to push the cork out from the inside. At that point, I might as well swap them, but it might not be worth it cause that's just more time.

#3. I never re-hooked up the canister vacuum lines (outside the one that goes to the tank, which was never messed with because it wasn't pertinent to swapping engine). The canister is on drivers side right in front of the fire wall (where the battery would go if the battery was on drivers side). There are 3 lines coming off of it, and are marked on the canister. The middle one, which goes to the tank (hooked up), a fat one that says Bowl that is going nowhere, and a thin one that is marked as PVC, and is just laying there. I have a holley 1850-2 (4160 series 600cfm 4bbl) carb. The Carb's PCV Port (rear passenger side of carb) has the PCV on it and is going to passenger side of valve cover. On my carb, the spark port is going to distributor, so that's fine, but there is only 1 more port I can see, and that's the ever mysterious port on the bottom front of the carb, which is capped. I know from looking at the carb manual that the front port is Full Manifold Vacuum Port, but again, it's capped. So basically, I have 1 unused vacuum port on the carb (which is capped) and 2 available vacuum lines from the canister, which I know went somewhere when I had my 258 in the jeep. Anyone have any idea what I should do with them? If they really go nowhere (like maybe the pcv one since I have pcv from carb), then I'll cap the canister ports. But if they do go somewhere, where would they go? I'm assuming this is leading to a vacuum leak, as the canister is going to be pulling a vacuum.

Thanks for the help guys. Any help would be greatly appreciated. Even if you only know 1 of the 3 questions I asked, any help would be appreciated.

Pete

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Last edited by Big_Pete1999; 09-08-2011 at 04:18 PM.. Reason: **Updated on last post**
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Unread 09-06-2011, 01:40 PM   #2
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I was wondering if I maybe had a vapor lock issue, cause I do have true dual exhaust the dumps in front of rear tires, and the fuel pump is the mechanical one that sticks out of the passenger side of the 350's block, so the fuel line runs close to my exhaust, and then across the engine to the carb, but from what I'm reading on vapor lock, my jeep shouldn't start right back up, so that has me super stumped.
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Unread 09-06-2011, 01:45 PM   #3
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When you are at a stop, holding down the brake pedal, does it stay nice and tight or does it slowly creep downward? If it's creeping downward, you could have vacuum leak in your master cylinder or the vacuum line going to it. At some point these leaks are large enough to stall you.
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Unread 09-06-2011, 03:07 PM   #4
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Brakes were always tight, but yesterday and today, I had to push on the brakes practically to the floor before they caught. I'll check master cylinder for leaks. Should I also just go ahead and cap off the evap canister lines?
You're the first person to reply, so I really appreciate it and will go out and try it.
The jeep didn't stall today on my way back from school, but of the 4 stoplights I actually had to stop at, the first 2 of them I had to touch gas cause it sounded like it was wanting to die, the other 2 it idled fine.
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Unread 09-06-2011, 03:19 PM   #5
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I'd definitely check the master cylinder and the line going to it. I wouldn't cap off any evap canister lines since it sounds like the only one connected is the one for your fuel tank. Seeing that you aren't putting any vacuum into it, I doubt it's actually doing anything at the moment. Perhaps your canister is bad and the PO decided to bypass/disconnect it?

You'd be wise to take care of the PCV problem and also to reconnect a working canister.
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Unread 09-06-2011, 03:34 PM   #6
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Well, the PO had it connected, but it had the 258 I6. After a few years of driving, the engine threw a rod on the side of the freeway. I opted to do an engine swap to the 350 Chevy instead of getting the 6 cyl rebuilt. When I swapped it out, it kinda relegated the canister useless. That's why I was thinking of capping it. But hey, I might be able to figure out a way to reconnect it, though the Holley carb doesn't have the matching ports to easily figure it out.
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Unread 09-06-2011, 03:46 PM   #7
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sorry
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Unread 09-06-2011, 03:48 PM   #8
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well, if i read that correctly (i am sure i did not) The problem is cutting off when stopped, and the 1970 350's were carborated, so tune the carb to idle a little higher an you SHOULD not have the cutting off problem... Sorry couldnt help more
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Unread 09-06-2011, 04:01 PM   #9
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Quote:
Originally Posted by Tylerzap View Post
well, if i read that correctly (i am sure i did not) The problem is cutting off when stopped, and the 1970 350's were carborated, so tune the carb to idle a little higher an you SHOULD not have the cutting off problem... Sorry couldnt help more
I was kinda thinking about doing this first. lol. Guess I should go ahead and do it. I don't have a gauge, so I am leery of messing with the rich/lean mixture, which I might want to do if I adjust idle. Maybe local shop would do it real quick for a few bucks. lol
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Unread 09-06-2011, 04:19 PM   #10
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Quote:
Originally Posted by Big_Pete1999 View Post
I was kinda thinking about doing this first. lol. Guess I should go ahead and do it. I don't have a gauge, so I am leery of messing with the rich/lean mixture, which I might want to do if I adjust idle. Maybe local shop would do it real quick for a few bucks. lol
Exacly, I would just have them do a full tune up of it (or if you have the tools you do it) and replace the spark plugs, oil, ect.

I couldnt imagine them charging more than $20, or $10 for a matter of a fact for the carb tuning if you dont want, or cant, tune a carb... Just remember- If you dont know what you are doin, dont touch a carb... my grandfather blew up a engine when he was young messing with a carb...

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Unread 09-06-2011, 04:31 PM   #11
Big_Pete1999
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Quote:
Originally Posted by Tylerzap View Post
Exacly, I would just have them do a full tune up of it (or if you have the tools you do it) and replace the spark plugs, oil, ect.

I couldnt imagine them charging more than $20, or $10 for a matter of a fact for the carb tuning if you dont want, or cant, tune a carb... Just remember- If you dont know what you are doin, dont touch a carb... my grandfather blew up a engine when he was young messing with a carb...

I hear that! I've tuned a few before, but that was a good 10+ years ago, so yeah, I'm not touching it. lol
I changed my oil about 100 miles ago, and plugs only have maybe 500+ miles on them, but if it's a carb that is out of tune, they might be fouled. I had the carb tuned, but it was before I got my exhaust on it, so I know it needs another one, albeit minor tune.
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Unread 09-06-2011, 04:33 PM   #12
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Thing runs fine at speed and then dies when you stop. Still sounds like a vacuum problem to me. When you are at speed and hit the accelerator nice and quick, does it jump and get ready to go or does it dog out? Could be distributor weight springs or something like that.

Check the easy things first. Vacuum leaks.
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Unread 09-06-2011, 04:36 PM   #13
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Quote:
Originally Posted by Bakunin View Post
Thing runs fine at speed and then dies when you stop. Still sounds like a vacuum problem to me. When you are at speed and hit the accelerator nice and quick, does it jump and get ready to go or does it dog out? Could be distributor weight springs or something like that.

Check the easy things first. Vacuum leaks.
It always seems responsive when I drive, but I'll pay extra attention tonight when I drive back to school (also taking night classes). I replaced the points distributor with an HEI when I was finishing up the swap and getting ready to turn over, so hopefully that thing is ok, but I'll check that too. I really hope it's a "little thing" that is going on.
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Unread 09-08-2011, 04:17 PM   #14
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Ok
So today I brought a screwdriver with me and left my house.
In my transmission guy's parking lot, I raised the idle speed half a turn, and that seemed to help a lot with the stalling when I come to stops issue. At this point, I had already driven to school and back. On the return trip from school is when my jeep always wants to stall at stoplights (while either in neutral or clutch pushed in and idling). So while I know raising the idle speed is keeping it from stalling, it was still kinda rough.

Into Checker Auto I go. I pulled out the wine cork that was in the PCV valve's spot on the driver's side, bought a new hose, and put the PCV valve in it's rightful spot (front driver's side). Instantly, my jeep ran like new. I of course had to take my valve cover off to get the cork out, which is why I've put it off for so long.

Anyways, my jeep fired up 1st crank, which is normal if it's cold, but not normal when it's warmed up. My jeep idled better, drove smoother, and when I came to stops, it was "sweeter than yoohoo." ~Roy Munsin

Thank you guys on here so much. I ended up doing what I thought needed to be done anyways, but you guys were instrumental in giving me the kick in the *** that I needed (such as the motivation to take off valve cover). I'm hoping this is a permanent fix. My next question is this....

Should I buy some sort of engine cleaner (internal) that is a gas or oil additive? I ask because surely my pistons are gunked up from the PCV valve issue, and if so, what products do you guys recommend?
Thanks guys!
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