I got a 1990 cherokee laredo 4door 4.0 straight 6, 4x4.
When i crank it over it just runs for one sec and dies and wouldn't stay running. Ive put in new map sensor, crank sensor, new battery, and Tps, and then it started to stay running but still idles down and dies, Runs lean and rich. Next Ive put in new fuel pump, filter, and pressure regulator, and now it stays running and doesn't die but lacks power when you put into drive, you push on the gas and you get nothing outta of it, just bogs down and wants to die like it starves for gas, but if you left off the gas, it will coast its self fine.

Ive unplug the 02 sensor and it still ran the same. The catalytic converter is fairly new, the fuel rails and injectors are fairly new. And the jeep has been sitting like this for 3years now, i just tinker with it from time to time.

Theres no blow by, sparks plugs are not foul, distributor, plug wires we're all new before it had problems. Throttle body is clean same with air cleaner. And ive bought a new air idle sensor but it still ran same so i took it back, that was before i put in new fuel pump, filter, and regulator was installed. Also on that note, the old tps ran better then the old so i put old back in and still have new for spare.

Things I haven't tried is doing a fuel pressure test. Which i should.
This jeep has about 300,000 miles on parts that i haven't replaced.
Motor is a rebuilt has about half that or so.

Any suggestions on what my problem might be electric or Mech?

 

tps adjusted ?

 

I have but not recently

 

Reset the ecu

 

Swap the fuel pump relay check your grounds

 

I'd try to borrow a fuel pressure gauge and see if you have the right amount of fuel pressure. Sounds like it's running out of gas. Is there a gas smell along the fuel rail?

 

Thanks for reply.

No there is no gas smell along the rails.
I started it up couple days ago after a ecu reset which did nothing.
It runs and starts up just fine, and idles sometimes at 800 but after touching the gas it begins to run lean and rich, idle bogs up and down like it starves for fuel, when you gently ease into the throttle it revs up fine but if you just stomp down or give good pressure it sputters then takes off (only in park)
when you drive it you get nothing outta of it, just sputters and putts down the road no accel at all.

 

Check the fuel pressure next.

 

I double tested the fuel pressure last night both readings gave me 13-15 psi
Gonna check the lines later today.

 

Check what lines? Sounds like the fuel pump is toast.

 

If I had low pressure on my 90, I might check the voltage coming out the rear of the ballast resistor to the pump, there near the air cleaner. (around 10 should be enough). Also don't those have issues with the tube from the the pump, to where the fitting comes out through? I mean, a new pump makes sense, but don't be surprised if you don't find the tubing funky when you extract the old one. Also to be thorough, I guess you can pinch off the rubber return line to rule out the regulator. I little tough to reach. The metal tube off the regulator goes to rubber down there by the steering column/shaft. I guess I haven't seen people posting trouble with the regulator though.

 

Check the ballast resistor on the left fenderwell (up front) as well.

It can be replaced if bad, or eliminated outright with a jumper wire (I did the latter.)

It was added mid-1988 to reduce NVH (Noise, Vibration, Harshness) issues from the fuel pump running - by reducing current to the fuel pump when it's running, you get somewhat less running noise from the pump motor.

If you want a quiet ride, buy a Caddy or a Lincoln - this is a Jeep! A little pump noise never hurt anyone.

 

The 2 main fuel lines. We cleaned them out with air compressor also shot some brake cleaner hooked it all back up. And it runs super lean still starves for gas. And the fuel pump is new.

I unhooked the pump from the filter, turn key on, got gas shooting. hooked it back up then unhooked filter from main line. turn key on, got gas shooting from filter. So i know those 2 are working.

My question my dad had ask was is there a specific way the hoses need to cycle? Cause when he air compressed the line that's hooked to the pressure regulator that line shot into the fuel tank. And the filter line shot up through the rail and out the regulator.

 

Pretty sure fuel comes from the tank/pump, through the filter, then to the rear of the rail. There it's held to 31, 39 LBS by the regulator at the front where it's allowed to return to the tank, from that line going down off the regulator. That's the one I mentioned you can squeeze closed, down where it turns to rubber to prevent fuel from returning to the tank. (to rule out the regulator not holding pressure)

People DO get bad pumps. Airtex especially get's allot of bad press here. Then there is that connection to the pump inside the tank. I see NOW that you have been there. Still there is a chance something didn't go right there.

Really like said, that ceramic ballast resistor on the inner drivers fender, (orange wires),(can be bypassed), and needs to shoot power out the rear terminal to the pump. I don't know right off where the pump grounds, course that needs to be good too.

Let us know how it goes! You'll get it!