99' Jeep 4.0L, wont start

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Apr 13, 2015 | 01:21 AM

#16

DFlintstone

CF Veteran

Joined: Aug 2011

Posts: 10,489

Likes: 24

From: Nor-Cal Coast

Year: 90,84

Model: Cherokee

Engine: 4.0,2.5

Quote:

Originally Posted by DFlintstone

the MAP got no vacuum which would make it very rich. I think you have a little elbow under your MAP on the TB you can check as well as it's wires. ___________________________Bad, separated fuel/ethanol happens.......

With the wires right, maybe be sure that MAP & it's vacuum are OK.

Apr 21, 2015 | 04:22 PM

#17

CheapCharlie

Thread Starter

Newbie

Joined: Mar 2015

Posts: 9

Likes: 0

Model: Cherokee

Vacuum

So today I blocker off all vacuum ports, and it would make 16 inches. Also I sprayed ether all around the intake manifold gaskets. no leaks were found.

Now with the engine running, I can operate the throttle by hand and run the rpm's to 1300 and it will run smooth and it makes 20 inches of vacuum. But as soon as I move the throttle it starts sputtering and loosing its vacuum.

The new question is, why is the vacuum so low? Valves/springs or a poorly placed cam shaft, are the only things I can come up with.

And now I have been in contact with a tech for Gear Head Engines. He had me loosen the rocker arm bolts, like a full turn loose. First the rocker bolts were way tighter than my book said they should be. So I re torqued all of them to 21 ft lbs. That actually smoothed it out at idle and raised the vacuum 1". But if I tried to throttle up it would just sputter. Then I loosened the rocker bolts 1 full turn, it idles ok but it sputters when I try to rev it up, oh and the rockers rattle LOL.

Charlie

Last edited by CheapCharlie; Apr 22, 2015 at 09:17 PM.