Fuel filter changed, no change with engine running. Next will be fuel pump. O2 sensor looks good, while measuring.
BTW: where is injector and how to remove? Is on the internet any maintenance manual to see? ideally illustrated part catalog, or something like that.

 

Do you have an exhaust leak before the O2 sensor?, even a small leak can fool the O2 sensor into sending the wrong signal to the ecu.

 

No, there is no leak in front of O2 sensor. But yesterday I measured fuel pressure, during driving. When engine runs good fuel pressure is about 120kPa after few hundert meeters, pressure starts descent, and engine starts be lazy, when pressure reach 80 kPa, engine has rough running, than pressure drops to 60kPa and engine goes very bad and car isn't able to go. Than I relase the gas pedal, pressure starts increase and car goes well, afer pedal to the metal it starts again. So I think, thai it can be only two things. Fuel pump, or pressure regulator. I let you know, if problem is here, after replacement of fuel pump.

 

Hi Jelen, the fuel pressure should be 45 psi which converts to 310 kpa so it must be pump, regulater or blocked filter. Martin.

 

Thank you very much for your info.
Filter is new, so I think it must be pump or regulator.
Injection is single point, that pressure is for single point? I think, that single point has little less, than multi point. I have another single point car, and it has about 150kPa, I had Mercedes Benz W126 and it had about 400kPa. So if pressure must be 310kPa for single point, I must change the pump. Than I will change the regulator.

 

Sorry Jelen the pressure I gave you is for the multipoint, not sure what it is for your single point. Martin.

 

Jelen, I looked in my manual and it says that the fuel pressure should be 14 to 15 psi for a single point,thats 96 to 103 kpa at idle, if it is a lot higher the fuel return line could be blocked.

 

Yes, it's about my press now. I have 120 at idle. Do you know, how much it should has during drive? When I'm driving, it drops to 60 and car stops. But I think fuel press should be same at all.

 

Jelen, I would think the pressure should be constant, I have a 97+ XJ with multi point and that runs a constant 45psi. If you Google 1987 Jeep cherokee manual there are several downloads for manuals. Martin.

 

Yes, I found any manual here:
http://jeep-manual.ru/index.php?page=19
it says:
,,An electric in-tank fuel pump supplies fuel through the fuel
filter located under the right rear floor pan to the throttle body,
maintaining a constant operating pressure. Fuel enters the fuel bowl
reservoir of the throttle body through the injector and overflow type
fuel pressure regulator. The fuel pump is controlled by the ECU.
A
ballast resistor attached to the right side of the plenum chamber,
reduces fuel pump speed after engine is running. The resistor is
by-passed in the "Start" position."

only diference is, I have fuel filter on the left side, not on the right side.

so I think I have faulty pump, or regulator. Or maybe that resistor, it can be faulty after warming. On wednesday I'm going to remove old pump and order new one.

 

Hey man. his dollar value is probably worth way more than ours... so $100 here is probably $150 there

 

hey Jelen, wanna try something to diagnose it? get a block of wood and a hammer, hold the block of wood against the filter, and give a couple of good but gentle hits. (you don't wanna break it, but you may loosen some crap in there). then test drive. If its better, you know its the filter.

Good Luck

 

oh Jelen, how did an 87 XJ end up in the Czech Republic?

 

Thanks for tip of hit to the filter. but filter has been already changed. New one is installed and problem is still here. Now I'm going to change the fuel pump.

Previous owner bought this jeep in California and brought it to CZ, than I bought it from him.

Of course, my dollar value is little bit more, than yours, but 25 dollars for the new pump is still very cheap. For example, one dollar is for one loaf of bread, or one beer.

 

Today I removed in tank fuel pump, connected to battery, and it's noisy, something rattle in pump. So I think, here is definitely fault.