I acquired a 1992 XJ along with a crate motor and a parts XJ. I have connected everything that I know to connect. When trying to start it, it takes forever to crank then goes upwards of 3000 rpms. New Standard sensors on throttle body. Cleaned throttle body before installing. I'm at a loss. I retightened the intake/exhaust manifold thinking that there might be a leak there, but no. All vacuum lines that I can see are connected. Replaced fuel pump and filter and fuel pressure regulator. all new sensors in intake. New distributor and is timed correctly. All ports on vacuum canister have lines going to something or are plugged. I know I must be missing something, but I don't know what.

 

Clean the IAC and check for leaks with some carb cleaner spray would be my first suggestion.
Did you use a new gasket on the TB?

 

The intake manifold can appear and feel like it's tight but be hung up on one or more of the locating dowels.

 

Roler, thanks for the reply. I'd check for leaks if I could let it run. It is a new engine and I shut it off when it gets up to 3000 rpms. It is climbing higher than that when I shut it off. I cleaned the throttle body when I installed it. New IAC, new TPS, new gaskets on everything. I even replaced the IAC and TPS again yesterday. Didn't replace MAF sensor, but pulled the one off of my donor XJ and put it on. Scratching my head.

 

Thank you. I have looked at all of the mating surfaces that I can see, and they all appear to be flush. I am going to get underneath it and see if I can see more or get a mirror under the manifolds and see what I can see. If I knew this was going to be such an issue, I would have installed the intake and exhaust manifolds before I dropped the engine in. Lol.

 

That's what I do. Install them before.

I think you're on the right track now.

 

Thanks. I'll update this thread when I figure it out and will try to include photos. I don't want someone else to suffer from this issue.

 

Just thought: reset the throttle cable yet?

 

That's exactly what it was. I reamed out the holes on the intake and it mounted flush. To find the leak, I attached a hose to my bee smoker and pumped smoke into the intake with the engine off. Smoke started coming from the under side of the intake manifold, so I removed the intake and did some surgery on it. Now it starts, although it takes a long time to start, will die randomly, and has no power under load. Like none. If you mash the accelerator to the floor, it just spits and sputters and very begrudgingly starts to accelerate. I'm currently scratching my head again. Also the check engine light comes on intermittently.

 

The check engine light is something to pursue

 

Thanks for the reply. Yessir I did that. Or at least the kickdown cable. I have not looked at or seen how to adjust the throttle cable, but I will look into it.

 

Sometimes the terminology gets mixed up.
This is the one I'm referring to - see video

 

yessir I did that. There’s a little slack in the let’s call it “accelerator” cable, so I will replace it, as well, but that shouldn’t affect it if I understand how it works. I am still going to get the code reader. I might check for obstructions in the exhaust, as well. The vehicle sat in a pasture for an unknown amount of time before I got it with the exhaust disconnected, so it’s not beyond reason that there could be a mouse nest or something obstructing the catalytic converter as well. It never occurred to me to check that, or at least blow it out from the tailpipe end to eliminate that possibility. It might explain why it idles okay, but doesn’t respond under a load, since it is just a big air pump. We’ll see! Thanks for the reply. And your insight. 😉

 

This is where my thought has been but it wasnt exactly clear the condition of things. I think youd see a more immediate test result if you drilled a 3/8 or larger hole just before the catalytic converter or the muffler than pushing air from the tailpipe.

usually pulling the 02 sensor from just before the cat is a good way to test this out but if I remember right the rear O2 is after the cat on these - thus the drill-a-hole method.

 

the O2 sensor is upstream from the catalytic converter. The 3/8 hole idea might be the ticket!