Mechanic Help

[deltadukman]

I need a mechanic that sho'nuff knows his chit on engine vaccume. Prefferrably one that knows a little about old jeeps. Any help? Its probably something simple, but I cant figure it out.

[Bull Duck]

When all else fails, ask Dirt!

[deltadukman]

But Dirt is at Donaldson(I think). No doubt he knows. I took some stuff apart to put a new intake/exhaust manifold gasket on, and now when I slow down and bring it to a stop using the breaks, it chokes it down. Also, the previous owner had the vaccume advance from the distributer unhooked and wanted to see if it would make a difference if it were hooked up or not.

[Buckwabit]

That jeep will be the death of you.....

[Buckwabit]

I'll give you $500 for it today....CASH....

[MudHog]

What you need? I helped a friend of mine work on his YJ that was full of vacuum crap which is mostly all emissions related.

[torch]

delta does that jeep have power brakes. Does it have a brake booster. Sounds like the diaphram has a hole inside the booster. If so don't run it cause it will burn up valves.

[LODI QUACKER]

I cant help you with your problem other than to say this. I had the same problem on my 90 yj. I have gotten rid of 95 % of my vac. crap, good luck is all I can say and when you get a chance convert it and get rid of that vacume system.

[BR549]

But Dirt is at Donaldson(I think). No doubt he knows. I took some stuff apart to put a new intake/exhaust manifold gasket on, and now when I slow down and bring it to a stop using the breaks, it chokes it down. Also, the previous owner had the vaccume advance from the distributer unhooked and wanted to see if it would make a difference if it were hooked up or not.

You definately have an air leak. Question is where. It could be on the intake gasket u changed. Was this problem there before u changed the gaskets? If so most likely u have a bad brake booster or the line to it is unhooked. Go to your booster and trace the line down. It must go to a fulltime vacume port on the intake or under the carb. If it is hooked up properly, unhook it and plug the port to where the air cannot get back into the engine. If the problem goes away then the booster is your problem. As far as the distributer goes, not sure of ur model but electronic ignition takes full time vaccume and breaker point takes part time vaccume.

[MudHog]

Vacuum diagram for a YJ:

[LODI QUACKER]

NNNNNOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!!






That schematic gave me nightmares for about a year!!!!!!!!!!!!!!!!

[deltadukman]

Ok. Mine is a 1980 with a 258 straight six. Most of my vaccume stuff is off of it. The vaccume advance from the distributor in unhooked and has been. I have a line from my pcv to the air breather, and one on the other side to the carb. On the back of the air breather, there are two sets of two of two hoses that I have routed to some little "tubes" 2 on the front of the carb, and two on the back side. The brake booster is hooked up to a large port on the back of the crab. Torch, I was told that the diaphram issuse would be present when the brakes were pressed even when sitting still. It is only when stopping under load...the harder I stop, the worse it wants to "cut out" and die...went by a mechanic this mornig, and he seems to think it is leaking vaccume around where the shaft goes into the carb for the accleration. I have since heard that is a gimmick and dont trust it. I have been looking around, and someone suggestted a bag EGR valve. I really dont need it, but I am tring to figure out where it is.

Buckwabbit...KMA

[MudHog]

It's not that hard to figure out. I used a different one when I worked on my buddies YJ, but it's all the same.

[BR549]

Ok. Mine is a 1980 with a 258 straight six. Most of my vaccume stuff is off of it. The vaccume advance from the distributor in unhooked and has been. I have a line from my pcv to the air breather, and one on the other side to the carb. On the back of the air breather, there are two sets of two of two hoses that I have routed to some little "tubes" 2 on the front of the carb, and two on the back side. The brake booster is hooked up to a large port on the back of the crab. Torch, I was told that the diaphram issuse would be present when the brakes were pressed even when sitting still. It is only when stopping under load...the harder I stop, the worse it wants to "cut out" and die...went by a mechanic this mornig, and he seems to think it is leaking vaccume around where the shaft goes into the carb for the accleration. I have since heard that is a gimmick and dont trust it. I have been looking around, and someone suggestted a bag EGR valve. I really dont need it, but I am tring to figure out where it is.

Buckwabbit...KMA

It sounds like ur problem is twofold! 1. Your brake booster is easy to check. Just plug it off from the engine. And yes it would effect it any time the brakes were applied. Moving or not! #2 you must have vaccume to ur distributer! Electronic ignition has to have fulltime vaccume! The advance in ur distributer works opposite of a breaker point dist. Without vaccume the advance will stay fully advanced instead of only advancing under power when the vaccume falls off. You can run a breaker point ignition without it because the centrifical force will advance it as the rpms come up and retard it as they go down. Its totaly opposite for hei! Find u a fulltime port (has vaccume at idle) and hook it to the distributer. You will probably have to reset the timing should be around 8 to 10 deg btdc at idle and advance up roughly 20 degrees or so when reving the engine up to appx 3500 rpms.

[deltadukman]

The thing is, it wasnt doing this before I started messing with the intake and exhaust gasket replace. Well actually, it started going bad at the front, and was causing it to not idle. Fixed the gaskets, and then this started up. Is there any validity to the throttle shaft coming out of the carb casuing it to leak. When I bought the jeep, the vaccume advance wasnt hooked up at all and it was running fine. What do you think that could be from?