Hi all.
First Im sorry, Im not native english speaker...
I have 1989 cherokee (AT/AC) 4.0.
It has some mysterious engine problem. When I start the engine it takes about 10-20 seconds. When it idles then one or two cylinder will fail I think, anyway it is choppy. When I’m accelerating slowly the engine fails, when I do it extra slow the engine fails completely (shuts off). When I’m driving at solid speed the engine runs, but after some time it goes choppy again. When I’m accelerating very strongly (pressing the pedal to the floor), then the engine “thinks” a moment and runs well. Acceleration is normal and the engine has the power.
So I have changed wires, fuel filters, spark plugs, MAP sensor. But the engine still has the same problem(s).
I suspect that on problem can be in fuel pump and/or vacuum lines. Also I found one resistor, in under hood (driver side).
So my question is what may cause the problems? Also does anyone have a vacuum diagram? Does anyone know how big the fuel pressure should be?
-------------------------------------------------------------------------
This message was posted also to other jeep forum, but guys didn't know mush.
-------------------------------------------------------------------------
So, yesterday I decided to look those vacuum lines. I closed EGR system completely (solenoid and sensor are also disconnected). It didn’t make any difference… Then I disconnected the vacuum line between vacuum fitting and air cleaner, I left the system open, and the idle speed raised and the engine runs ok (if system is open, it takes too much fuel).
My question is how the vacuum system operates? How it reacts to rpm’s?
I suspect, that the problem may be caused by fuel pump. Or does someone have other solutions?
First Im sorry, Im not native english speaker...
I have 1989 cherokee (AT/AC) 4.0.
It has some mysterious engine problem. When I start the engine it takes about 10-20 seconds. When it idles then one or two cylinder will fail I think, anyway it is choppy. When I’m accelerating slowly the engine fails, when I do it extra slow the engine fails completely (shuts off). When I’m driving at solid speed the engine runs, but after some time it goes choppy again. When I’m accelerating very strongly (pressing the pedal to the floor), then the engine “thinks” a moment and runs well. Acceleration is normal and the engine has the power.
So I have changed wires, fuel filters, spark plugs, MAP sensor. But the engine still has the same problem(s).
I suspect that on problem can be in fuel pump and/or vacuum lines. Also I found one resistor, in under hood (driver side).
So my question is what may cause the problems? Also does anyone have a vacuum diagram? Does anyone know how big the fuel pressure should be?
-------------------------------------------------------------------------
This message was posted also to other jeep forum, but guys didn't know mush.
-------------------------------------------------------------------------
So, yesterday I decided to look those vacuum lines. I closed EGR system completely (solenoid and sensor are also disconnected). It didn’t make any difference… Then I disconnected the vacuum line between vacuum fitting and air cleaner, I left the system open, and the idle speed raised and the engine runs ok (if system is open, it takes too much fuel).
My question is how the vacuum system operates? How it reacts to rpm’s?
I suspect, that the problem may be caused by fuel pump. Or does someone have other solutions?