DFlintstone

No time, raining and mud, 300 miles from home. My original 90 was rear-ended and somewhat totaled by Mrs. Amber Hammer. (yes, Ms. Hammer!) (Same 1990 4.0/AW-4)

My new $600 Jeep (or twice that), is pretty clean! BUT.....

Always a bunch of brake petal travel. I have not checked the adjusters. He sold it cheap because the shop couldn't figure it out. I intend to check the rear adjustment, AND that the auto adjuster threads are correct for left and right.

This Bendix 9 with anti-lock has a new warenteed pump installed. (I think it's a pump). First thing, cold, I hear the pump run. Besides the excessive petal travel, brakes feel good. After just a bit of knocken around, it changes, to feeling like there are no power brakes. (not sweet being near the floor and needing so much pressure) I do not hear the pump run with ign on.

I gather from Cruiser that a WJ Vac/Master will go with modification. (and others), but that ain't happening here now. (more on that later in this tread)

It seems OK besides the excessive petal travel until it warms up, then no hear pump, no power brakes. Once maybe after under-hood heat had time to "migrate".

Am hoping Chuck or someone can provide that "magic bullet" to it's pump power failure. My ohmmeter is dead and it's doing plenty of other tricks to point towards grounds. I wonder if the ECU is even in involved, it has it's own puter' under the back seat. So there is a start.

New Paint, very smooth, strong and sweet, 180K, rebuilt transfer case. New $1,500 ABS? pump.

Metmknice

Replace the POS system with a 95-up/WJ etc dual diaphragm booster/master cyl.

ThatDude114

Your pump is starting to go. As you drive around and use your brakes it starts to leak from the built up pressure inside the pump. The pump has a lifetime warranty but some dealerships won't even touch it, and others can't find the parts. If they did replace the pump it'd just happen again eventually. Its super to replace the system with a standard braking system. You'll need a booster, master cylinder, and possibly a brake pedal from a non abs Cherokee. Also you'll need to either use adapters or use new brake lines because the fittings on your current lines are a different size. Some people have had to fiddle with or replace the brake light switch but I didn't have to and I didn't have to replace my pedal either. When you start to disconnect the abs system you need to disconnect the battery and pump the pedal 50 times to relieve pressure in the system. If you have any questions feel free to ask, I just finished up converting my '91 a couple weeks ago.

DFlintstone

Agreed. And to make the circle of **it complete, waz 1/2 off for, say a WJ booster here till 5:00 Today ($20)

I appreciate that Dude. Truth be told, I was not sure how the business bolted on when I looked at a $20 WJ booster/master (only) yesterday. My back was killing me and the thing waz way up high. NOW I GET IT THAT IT BEING WAY UP THERE WAS A BIG PLUS! (could reach the bolts). In any case that would be to grab a booster/master to install at home. Hopefully my local guy won't be much more than double.

My hope is that the new pump that was just installed.....will get me home. What I'm fishing for, ......it runs and works, then goes silent. Is that the power to it? Or will it just go dead without making any sound?

DFlintstone

Here is the new pump below the expansion bottle, then the brain under the left rear passenger seat, then a view of the mess this thing makes out of the space under the hood. (the lines and thieir "protection" fill it up). (Pucking Mess) Then last, I only noticed two that were tagged, under the rear seat. A pic of one tag.

Radi

Roadside troubleshooting a Bendix 9? Man, are you asking for punishment, lol.
The pump runs on start up to pressurize the accumulators. It's supposed to run again as they deplete, but yours apparently isn't. There is a relay and pressure switch near the pump that controls that.
There is also an accumulator low pressure switch that is supposed to trip the dash warning light and force the pump on if the primary circuit fails.
There is a thermal fuse in the pump that temporarily shuts it down if it reaches a certain temperature. This can happen if you have a leak and it keeps cycling.
Any of that stuff could be failing, or bad wiring, or as you mentioned- bad grounds.
The system shouldn't leave you with no brakes, just no power assist.

Other than that- looks nice! I like the white.

eta: not to be obvious, but the fuses are all good? Do the ABS/Brake warning lights come on?

DFlintstone

Usually both, but the amber? ABS? one goes off sometimes. The red brake is always on.

DFlintstone

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freegdr

Found this info a while back not sure if it will help any ...http://www.aa1car.com/library/abs_bendix9.htm

DFlintstone

Many thanks Freedgr, I'll be saving that. "an accumulator low pressure switch for signaling the controller if accumulator pressure is lost. The accumulator switch is a single terminal, self-grounding switch that remains closed during normal operation. If pressure in the accumulator drops below 1,050 psi, the switch opens and the controller illuminates the yellow ABS" < there's that!

freegdr

DFlintstone

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Radi

Wouldn't that be the isht, $1500 in repairs and a stumped mechanic, only to find the fuseholder was dirty?

DFlintstone

I guess he got it on warranty, then got panced 4 bills plus to instal it. Jury is still out, this AM it HAD run before I monkeyed with the fuse.

Do you "agree" that the play is likely the adjusters? And "B", your thoughts, could that cause the rest of the "cascade"? (or part of it}....

Radi

Well, the rear adjusters are the first place to look when you have too much pedal travel. I bet they are frozen up.
The other problem- the pump isn't cycling back on when the accumulator pressure drops (and the warning light comes on), I don't think is related.

I'm kinda stumped as to why the pump would run until the correct pressure is reached when you start the jeep, but not run again when the pressure drops while you are driving. I'm not that familiar with how the system works. Pressure switch? Brake controller?