Hellororo

Hello all, I have an 87’ XJ and am having some throttle problems. When I press the gas in low idle it will stall. In high idle it works fine. I have a few theories but am not sure where to go from here. This started happening at around 10000ft after driving up about 4000ft. It got up fine, but started with the issues on the way down.

TPS Issue?
Fuel Pump Issue?
Maybe some gunk got in my fuel lines due to low fuel level?

A video of the issue is attached below. Thanks for any help.

UPDATE:

I replaced my fuel pump and cleaned my c101 connector and this problem went away.

tjwalker

I would start with a simple test of fuel pressure. Must be done with a fuel pressure gauge which can be rented from many parts stores inexpensively if you don't have one. For your 87, you need approximately 31 psi of fuel pressure at idle. Now disconnect the vacuum line leading to the fuel pressure regulator under the hood and the fuel pressure should jump up to about 39 psi. If there is any raw fuel in that vacuum line, replace the fuel pressure regulator as it has a ruptured diaphragm.

The TPS can be tested and that would be a good idea. A simple search of this forum will get you the procedure to verify the TPS or Cruiser or somebody will post it up for you.

Never hurts to clean the throttle body and idle air control.

Good luck and keep us updated!

Hellororo

Thanks for the reply. I will try these things and post back with results to hopefully help someone else. I do know how to test the TPS so when I get a multimeter I will do so.

Roler

Welcome to the forum
And thank you for making a ready to click, clear demonstrating video of the issue!

As suggested -
I'd start with the free stuff: Cleaning the TB and IAC first, check the TPS 'sweep'.
Fuel pressure next


Cruiser54 will likely wake up shortly and join in...you tripped the Renix wire . Have you been to his website? He'll likely refer to it, plenty of tips for you there.

I'm sure we can help getting this sorted

Hellororo

got it. Plan on doing this all tomorrow. What exactly is a renix wire? I’ve never been to his website. If he posts I will check it out

Roler

Ha! That was a matter of speech, not an actual wire..

Your jeep is from around a specific era, Renix. There are a few, not many, but few knowledgable folks here specifically re those years, that have specific issues and solutions. You'll see them getting involved usually.

In the meantime: Cruiser54.com for tips and lots of info.

I should should get a dime everytime I refer someone there 😆

cruiser54

Wake up? I'm getting ready for bed!!

Anyway, go to www.cruiser54.com and complete Tips 1 through 5 before doing anything else.

Hellororo

So here is a little update. I’ve done steps 1-5 on this website and still a no go. I’ve tested the TPS and it’s outputting the correct voltage. I changed my crankshaft position sensor because I had a spare laying around and was out of ideas. My next idea is that either the cat is clogged or the fuel pump is actually bad. Here is another video showing a little more detail than the first. Any tips are appreciated.

Hellororo

checked it out, thanks. My c101 connector was actually full of black gunk. Probably good to clean it even though it didn’t fix it. I tried hooking an ODB reader to the XJ and was surprised there wasn’t a port for it. I guess it’s too much of a classic and I’m too young to know what came before 😅