Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 16 of 16 Posts

·
Registered
Joined
·
117 Posts
Discussion Starter · #1 ·
I am back in the jeep game. I just picked up a 90 yj with a 4.2. The rig has been sitting in a shop since 2008.
What I know..... the original motor blew up and the last owner purchased it with a 4.2 not in it and unknown details on the motor. he swapped out the blown up motor but let the jeep sit in his shop.
The motor is in and wired up. There are no fuel lines hooked up besides the main fuel line going from the pump to the carb. There is also no vacuum lines under the hood. It looks like there was emissions stuff taken off also.
Can I run this rig with no emissions?
Where can i find a good layout of where fuel lines and vacuum lines should be running?
I'll snap some pictures tomorrow.
 

·
Registered
Joined
·
1,020 Posts
Do you have emissions testing where you live? That will determine if you need to put the omissions stuff back on..the 4.2 was developed way before emissions it will run fine without it..as far as the fuel line I only run line and the only vacuum lines I have is for the advace, brake booster and CAD...my jeep runs fine...
 

·
Registered
Joined
·
117 Posts
Discussion Starter · #3 ·
it will have historic tags so question answered. Sounds like the vacuum lines are going to be my big issue.
 

·
Registered
Joined
·
684 Posts
If your state requires emission testing, then yes you'll probably need them. If your state doesn't then you might be able to get away with it.
It was common practice years ago to pull smog equip because most believed they were power robbing.
There are several members that can provide links to service manuals. They'll be along shortly :)
 

·
Super Moderator
Joined
·
12,670 Posts
If you don't need to have your Jeep emission tested, the best setup you can have is a HEI distributor and:
1)- A non stepper carter BBD carb (Stock BBDs on YJs had a stepper motor. Early 258 CJs and a lot of MOPARS had non-stepper BBDs).
2)- Motocraft MC 2100 or 2150 carb
3)- Weber Carb

That would be my preference in that order for carbs. They are all good. Other posters may dispute the order that I prefer.

Vacuum shouldn't be a problem. sccritterkiller has a real simple setup.
I suggest that you also run a PCV and a charcoal canister.

The little fitting on the back of the intake manifold sends vacuum to your heater control.

With the HEI, you can get rid of the PCM computer (on top of the heater box in the cabin) and the ICM (under the windshield washer bottle) plus a whole bunch of wires and sensors & controls.

PCM = Power Control Module
ICM = Ignition Control Module

Pic 1 is the fuel filter and carb plumbing. The vent line goes to the top of the filter position, not like shown in the pic
Pic 2 is a check valve installed to cure a "hard start after sitting for two days" problem.
These are old pics. I have since installed a non-stepper carb, removed a bunch of controls and wires and properly positioned my fuel filter.

Good Luck, L.M.
 

Attachments

·
Registered
Joined
·
117 Posts
Discussion Starter · #6 ·
How did you know where to run the lines. I don't have anything to start from. IS there any pictures or layouts I can find online.
 

·
Super Moderator
Joined
·
12,670 Posts
Here's a great resource!

Find a post by MudMagnetYJ and look in his signature. The last item in his signature is a link titled "Service manuals". Click on that link. Several more links will show up. There are links to Factory Service Manuals and a link to a few parts manuals.
Don't forget to thank MM for this fine service.

If you click on the FSM for your year Jeep, you'll find more information than you ever expected. From paint codes and engine repair to how to adjust a soft top.
If you click on the parts manual for your year Jeep, you should be able to find every last part that the factory used in the building of your vehicle. There may even be (at least) a hint of how the fuel lines are routed.

I don't have any pics right now and I'm headed out on an errand. Perhaps another poster has a fuel line routing pic, or I can post a couple later today.

Good Luck, L.M.

BTW, Hey MM, Thanks for the manuals.
 

·
Super Moderator
Joined
·
12,670 Posts
Here are a few pics if my fuel feed setup. I believe it's stock.

Pic 1 is where the line from the tank connects into the fuel pump and pressurized fuel goes up the line that's covered with corregated plastic that I added to help prevent vapor lock.

Pic 2 shows the line with corregated cover going into the fuel filter.

Pic 3 is the fuel filter and connections

Pic 4 is me pointing to the fuel overflow return line. This line runs under the engine and I assume it runs back to the gas tank.

Pic 5 is the vacuum fitting and line to the heater controls.
The light colored patch between the ground strap and the red & blue is where the PCM computer wires were. I riveted a piece of galvanized tin on the inside and sealed it with clear silicone.

Good Luck, L.M.
 

Attachments

·
Registered
Joined
·
117 Posts
Discussion Starter · #9 ·
Dude you rock. This will really help. As far as the other vacuum lines like the one off of the distributor and I think there are 2 ports on the bottom of the carb. Where do they go?
 

·
Registered
Joined
·
391 Posts
If you have a little extra money to spend, take a look at the Howell TBI (fuel injection kit) you'll be smog legal and can do away with 99% of the vacuum lines, add a CRT HEI distributor and forget about it. No carb tuning and it will run better and stronger than it did brand new. The initial investment may be a little high, but the lack of future headaches is well worth it.
 

·
Registered
Joined
·
1 Posts
Andrew2456, I just picked up an '89 with a 4.2 that has been sitting for a number of years also. I'm in the same boat, looking to clean up the engine bay of unnecessary emission equipment if possible. Mine is all original so if you want specific pics just let me know of what and I can send them over. I'm going to start working on it in the next few weeks so let me know which direction you decide to go.
 

·
Registered
Joined
·
117 Posts
Discussion Starter · #13 ·
That would be awesome. Currently looking to figure out where all vacuum lines from the carb go and distributor.
 

·
Registered
Joined
·
117 Posts
Discussion Starter · #14 ·
would I have to change the distributor there is a brand new one on the jeep now. I am thinking this is my best and easiest option.
 

·
Registered
Joined
·
391 Posts
Is it a stock or aftermarket (HEI?) distributor? It really doesn't make a difference as far as vacuum lines, as they both have vacuum advance.
 

·
Super Moderator
Joined
·
12,670 Posts
Search this forum for "HEI". There was a recent thread describing why a person should take the distributor advance vacuum from the carb body, rather than the manifold.

Good Luck, L.M.
 
1 - 16 of 16 Posts
Top