Jeep Wrangler Forum banner
Cancel

Idle/Brake/Vacuum Leak Issues

9167 Views 10 Replies 5 Participants Last post by  GotMudYJ, 
G
3
Okay I have a 1987 Wrangler YJ With a 4.2L 258 I6. Here are the symptoms; When driving my RPMs drop fast when I hit the brake Pedal. The RPMs Drop so fast that the engine stalls. Also I can't get the idle under 2000 RPM. I've rebuilt my Carter 2bbl Carburetor. Nothing seems to work. Also the previous owner took most of the stuff off the engine. {AC, Oxygen Sensor, Idle Solenoid(sol-vac), Heater and much more.) I've had the 4 Wheel Drive gear shaft break on me I had to buy front new calipers and new brakes. The previous owner plugged all the vacuum lines that he took off. Also What does the Line on top of the valve cover(the One closest to transmission) go to? That line doesn't seem to do anything I don't feel a suction or air flow. Could it be the brake booster? Exhaust manifold leak? Help! So I'd extremely Appreciate if someone could help me out. & Since I bought it, my Wrangler has become my obsession to fix it So I need help finding out what the problem is. I will be uploading pictures shortly. -Thanks for taking the time to read this.

Attachments

See less See more
Reply
Save
Like
1 - 11 of 11 Posts
G
I have more pictures if anyone would like to see.
Reply
Save
Like
harleydragon
sounds like your brake booster is bad..the hose on your valve cover should go to the base of your carb (probably on the back side)..once you get those problems repaired,if it still idles high,check for any other vaccum leaks.high idle can also be caused by the float level setting,throttle cable to tight,throttle return spring too weak,choke butterfly not open
Reply
Save
Like
90YJinPC
x2 on the brake booster
Reply
Save
Like
G
Could a missing float retaining pin be the problem? Im going to clear my venturies and check my vacuum on the brake booster tomorrow.
Reply
Save
Like
cmcgriff
X3 on the brake booster...


Sent from my iPhone using AutoGuide.com Free App
Reply
Save
Like
G
Im guessing the Brake booster needs replacing. Ill see about getting a new one. Do I have to unplug the MC to replace BB?
Reply
Save
Like
harleydragon
GotMudYJ said:
Could a missing float retaining pin be the problem? Im going to clear my venturies and check my vacuum on the brake booster tomorrow.
Click to expand...
that could possibly be your high idle problem .I doubt it but can't rule it out
Reply
Save
Like
harleydragon
GotMudYJ said:
Im guessing the Brake booster needs replacing. Ill see about getting a new one. Do I have to unplug the MC to replace BB?
Click to expand...
should be able to just unbolt it from the booster and pull it back enough to get the booster out..leave the lines connected
Reply
Save
Like
snowbrd84
Before you replace the booster. The vacuum line that feeds the booster from the intake manifold will have a 90 degree elbow/fitting where it plugs into the booster. That is not just a fitting, that is a check valve. Slide back the little metal retaining ring and take it off. You should be able to suck through it from the manifold side, but when you blow, it should not let you. If you can blow through it, then your check valve has failed and you just need a new one...
Reply
Save
Like
G
My issue was apparently solved when I adjusted my Stepper motor Needles in the back on the carb. And Put the EGR back on. The Booster seems to be fine now.
Reply
Save
Like
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Jeep Wrangler Forum
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!
Full Forum Listing
Explore Our Forums
JK General Discussion TJ General Discussion TJ Technical Discussion JK Technical Discussion YJ Technical Discussion
Top