Rerouting the 2150 Carb Bowl Line?

[wjamesbass]

The power valve on my 2150 is most definitely trashed so I will be following (Mr.) Ristow's rebuild sticky very closely when the the parts arrive, but for now I am studying the vacuum layout for my '88 and trying to work around an equally trashed vapor canister. However, for all the things I don't know about the emissions circuit I thought I would ask around about venting options. Specifically, I'm looking for ways to keep the bowl vent line active without using the canister.

Would I be able to reroute the bowl vent line to the PCV outlet tee behind the carb...

...or, could I run the carb bowl vent line directly from the carb to the fuel tank?

For what it's worth I have a vented fuel cap and the original air cleaner, which appears to be hooked up to the EGR and Dual CTO as described in the emissions diagram. Neither of the front CTOs (nor the NLV) are installed on this engine.

Finally, this vehicle does not figure into passing emissions anytime soon, so I got that going for me...

I will research this site and review the TSM before I attempt anything that I don't understand, but at this point I'm just as leery about plugging ports as I am in trying to reroute them.

Most appreciated!



89 Emissions Diagram:


__________________

[Ristow]

there is no reason to keep the bowl vent without the canister. that vent is only open (venting) when the ignition is off. the solenoid closes,shutting the vent off when the ignition is on. that vent must be closed when the engine is running. cap it off.

[wjamesbass]

Well there we go! Works for me just fine; one more potential leak plugged.

Pulled the carb off the manifold intake in preparation for the rebuild and it turns out the choke pull off vacuum fitting was epoxied back on a long time ago. Maybe it made it out of the mechanic's shop, maybe not.

I think simplifying the vaccum system is going to help a lot, and I appreciate the quick reply!

[FSJunkie]

You kinda have to cap it off without the entire rest of the vent system intact because there is no internal vent baffle in the carburetor to keep liquid fuel from sloshing out of the vent and you need a way to deal with that liquid fuel.

I put a 2150 on my early Wagoneer that has only a basic charcoal canister system and no valves or vapor separators like the 2150 was designed for. I capped off the bowl vent line. The carburetor doesn't care so it has no effect on how the engine runs, but you definitely don't want to leave that vent open to the air.

[wjamesbass]

I intend to wheel this rig along trails "as flat as Texas" for the foreseeable future.

The last experience I had with any thing resembling fuel slosh was driving my Dad's '86 Wagonneer down the street when the secondary, electric, fuel pump (to the secondary tank) evidently malfunctioned and flooded the engine bay until it lit but good.

Granted, this was almost 20 years ago and I was younger then but I still treat these (i.e., any Wagoneer) situations like a loaded weapon!

[Ristow]

The carburetor doesn't care so it has no effect on how the engine runs, but you definitely don't want to leave that vent open to the air.

it will run rich across the board with an external vent. external meaning a vent not in the same atmosphere as the venturi-the clean side of the air cleaner.

[JeepJeepster]

Check the fsm for your 88 for the proper measurements on your carb. That writeup didnt match what the fsm said for my 89.

[evdrummer]

it will run rich across the board with an external vent. external meaning a vent not in the same atmosphere as the venturi-the clean side of the air cleaner.

I'm having a lot of running rich/choke issues and with my missing charcoal canister the PO just vented it down behind the driver's side fender. Are you saying I can reroute that thing somewhere on the clean side of the air cleaner? Or should I more actively pursue rigging up a new charcoal canister to help my carb issues?

[wjamesbass]

I'm still trying to fine tune the electric choke on my 2150 and still run the EGR off the CTO and air cleaner but I have (temporarily) eliminated the charcoal canister. The catalytic converter and air pump are long gone as well.

The engine pulls almost 22" vacuum at warm idle and 12 degrees timing so I think I have eliminated the most serious leaks. But it still feels (smells) like it's running rich.

I think the consensus is to try and keep the charcoal canister, and I will likely work it back into my system this season. I also like the mention in another thread of using silicone tubing for emissions lines since it doesn't seem to dry out and crack like OEM rubber.

And I'll probably look into a 3 way cat, but that's for another post!

[Ristow]

The bowl vents are cast into the choke tower that sticks up I to the air cleaner. The external bowl vent is an emissions vent for underwood fumes with engine off. With no canister there is no use for that vent. Cap it off.

I'm having a lot of running rich/choke issues and with my missing charcoal canister the PO just vented it down behind the driver's side fender. Are you saying I can reroute that thing somewhere on the clean side of the air cleaner? Or should I more actively pursue rigging up a new charcoal canister to help my carb issues?

[FSJunkie]

it will run rich across the board with an external vent. external meaning a vent not in the same atmosphere as the venturi-the clean side of the air cleaner.

I should have worded my answer differently. What I meant was the carburetor will run the same either with the external vent plugged or hooked up to the factory vapor control system. Leaving the external vent open or able to suck air in from someplace will make it rich, as you said.

Hence why you cannot simply plumb the external vent to the charcoal canister, the gas tank, or anywhere else: because it will suck air from that location while running. The float bowl of the carburetor must be at the same pressure as the inside of the air cleaner, and if the external vent sucks in air from anywhere that pressure will not be the same and the carburetor will run rich.

If you use the external bowl vent, you MUST have a way of sealing it off when the engine is running. Some carburetors had a little check valve inside, but the 2150 does not, which is why it had the separate solenoid valve. Without that valve you're SOL.

[Ristow]

Exactly.

[evdrummer]

Thanks guys, that makes a lot of sense. I'll cap that vent off and see what happens. Also on the subject of carb issues, I have two concerns:

1) my vacuum at warm idle can't get higher than 18 when tuning it, but I keep seeing people talk about 20-22 when they're checking things. Does that sound like a vacuum leak somewhere? I've checked around, but haven't been able to isolate one.

2) My power valve came capped off from the PO. After rebuilding the carb, I recapped it, but if I understand correctly that means the valve isn't doing anything. Would this contribute to running rich and/or having a real hard time on cold starts? It should be routed to manifold vacuum, correct?

[Ristow]

A capped power valve vacuum source is doing something. It's leaving the valve in the open position which is the rich position.

[evdrummer]

In case anyone else is following this with similar problems:

Routed the power valve to manifold vacuum and plugged the bowl vent line that was open to the air...ran so much better this morning It's too early to tell if MPG has improved at all, but it didn't have any of it's usual cold morning hard starts, misfires on acceleration, etc. In fact, since my fast idle cam isn't working quite right, the idle was noticeably lower than usual when cold, which I assume is because it's running leaner than it used to be. Still have some light backfiring from the exhaust on deceleration to figure out, but I'll count this a victory for 10 minutes of my life in the morning.

Thanks for all your help!