Hi all,

I just bought an '87 Cherokee with 140,000 miles on it. It ran fine for the first week I had it. I changed the oil and air filter today. But, when I went to start it up after that it started fine, idled okay for about 2 seconds then the idle dropped and it started sputtering. After about 20 seconds of that it picks up and idles normally for about 3 seconds and immediately dies.

I'm assuming I knocked something loose while I was changing the oil and air filters, but I can't figure out what it is. I spent 3 hours double checking every connection I could find and still nothing.

I'm completely lost. This is my first jeep and older car, so I'm not too familiar with all that's going on under the hood.

Thanks for reading.

 

Did this symptom begin to occur IMMEDIATELY after changing your oil and air filter? If so, the area surrounding the air filter is what you must concentrate on. Get a good light and check all CCV hoses, vacuum hoses, etc. I don't see much that would be related to an oil change.

If you absolutely can't find anything, the first thing you should do is test your fuel pressure. This MUST be done with a gauge, which often can be rented from some local parts stores; call around for availability.

For your 87, you should have 31 psi at idle. Now disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Check that vacuum line for raw fuel; if you find that.....the fuel pressure regulator is shot.

Biggest tip I can give you? Get a factory service manual to help you along the way. You are going to need it. There is a lot of learning within those pages.

 

It started right after the oil change. The vacuum lines in it are pretty shot. The line from the top of the valve cover to the intake manifold had been taped together by the previous owner. One of the EGR lines is broken. However, it was like that before this issue so I'm not convinced that's the main issue. I ordered new vacuum harnesses just because. Not too expensive and the wife is letting me put some money into it to get it reliable. So, worst case scenario I'll see if they solve the issue when I get them in.

I'll check the fuel pressure tonight to see if that's the problem. I did change the fuel filter after it started acting up so I know that can't be it.

Thanks for your repsonse. I'll let you know what happens.

 

Gotta get all vacuum lines and CCV lines (to/from valve cover) replaced. And EGR lines too. Vacuum, CCV, EGR are all critical.

All of that plastic/rubber stuff breaks down over time and 30 year old components can cause many problems when they fail. None of these parts are expensive, all systems are critical and may likely be related to what you are seeing.

Take inventory of what looks bad and replace all of it. Then see where you are at. Testing fuel pressure is still a good idea. As is a full tuneup of Champion plugs gapped to .035, quality plug wires, distributor cap, rotor.

And don't forget about fluids. They are the lifeblood of your XJ. If the previous owner taped CCV lines, routine fluid changes were not likely high on their priority list!! Transmission fluid drain and fill, transfer case, differentials, coolant flush/fill, new 195 degree thermostat, possibly a wholesale replacement of all hoses, radiator cap. You get the picture. This vehicle is likely in need of a lot of TLC.

All of this stuff is not expensive, if you do the work yourself, which it sounds like you can! Good luck and keep us updated!

 

I ordered three different vacuum harnesses. They seem to be all that I need. For now anyway. I got that impression from the precious owner. Everything seems to be good for now. But, over the course of the next few weeks I plan on changing all fluids and flushing the coolant.

I checked the fuel pressure and it won't go above 10 psi. When I prime the fuel pump it'll jump for as long as it's on but quickly drop to zero. There isn't any fuel leaks. Could it be a fuel pump issue?

 

10 psi won't cut it. Not even close. You need 31 psi for an 87 4.0 engine to run properly. If I were you I'd consider replacing both the fuel pump for sure and maybe a fuel pressure regulator to boot if it looks ancient.

 

Bypass ballast resistor by airbox ...

 

Might have bumped that changing the air filter.

Mr. Walker also offers very sound advice.

Coupla things.

If you do have to replace the fuel pump, use only BOSCH.

Want some free and easy stuff to do to help the reliability?

Go to www.cruiser54.com and do tips 1 through 5 to start with.

 

It appears that I don't have a ballast resistor in my jeep. I ordered a fuel pump and regulator. I'll let you all know what happens in order of installing new parts.

I plan on replacing most things on it that are questionable.

One thing I'm unsure of is there are 2 wires from the TPS that are hard wired to the harness (ie. bypass the plug). I'm not really sure why. I initially assumed that it was a later model TPS and they chose to wire some things manually instead of changing the plug. I'll upload a picture if needed at some point. Just kind of concerns me because I have no idea why its that way.

 

Gimme a pic please.