90 Cherokee starting and running problem

Well I have replaced all the sensors on my 90 xj all new vac hose new fuel filter swapped out a couple fuel regulators new spark plugs on and on well it still takes for ever to start back firers when try to push gas and start once it's started push gas it dies I can push gas real fast to get to rev higher. I'm almost out of ideas mabe someone else ran into this before ? Any ideas ?

Any ideas . It's sad seeing it sit

Did you replace the Throttle Position Sensor? If so, did you adjust it?

I did replace it adjusted a bunch of different ways moved a little and try until I ran out of adjustment

There's only one way to adjust it:


RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Adjust the TPS until you
have achieved this percentage. If you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles—FOR ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the four-wire connector side of the TPS.
If you have ENGINE issues check the three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 08-27-2012

Check the vacuum line from the throttle body side to MAP sensor on the fire wall, test the MAP sensor.

Give us an exact list of what you have replaced, what you have tested and the exact results.

ON and on

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won't do it!!!!

Also list all the various symptoms, odd behavior and when they happen and when they don't! Take your time, make the list COMPLETE!

I did not adjust it like that.. Ok a list fuel rail, regulator ,cps, tps, egr, egr sensor,o2 , knock, map , all vac hoses, updated ground both dip stick and fire wall new spark plug cap rotor the other sensor on t/b

Tobyxj said:

I did not adjust it like that.. Ok a list fuel rail, regulator ,cps, tps, egr, egr sensor,o2 , knock, map , all vac hoses, updated ground both dip stick and fire wall new spark plug cap rotor the other sensor on t/b

Click to expand...

Need to adjust the TPS properly.

Ok what it's doing is it takes forever to crank it just cranks and cranks then when it does start it it idles perfect then I push gas it dies I can get it to run by pump it real fast. I've been away form it for a couple days in the morning I'll put the fuel gauge on it and see what psi I got and update

Tobyxj said:

Ok what it's doing is it takes forever to crank it just cranks and cranks then when it does start it it idles perfect then I push gas it dies I can get it to run by pump it real fast. I've been away form it for a couple days in the morning I'll put the fuel gauge on it and see what psi I got and update

Click to expand...

Good idea to check the fuel pressure.
And adjust the TPS properly soon.

The other "sensor" on the TB is not a sensor, it is an idle air controler valve, controls (does not sense) idle air flow rate, the EGR has transducer (on some) and an electric solenoid valve, no EGR sensors.

Does it have a good spark from the high voltage coil, the so called hot blue snappy spark?

Was the fuel pressure regulator new? Were any of the parts used?

Usually your problem is caused by
(1) a bad MAP sensor signal, which can be wiring, the MAP sensor itself or a vacuum leak in the line feeding the vacuum signal to the MAP, or a clogged port on the throttle body where the MAP sensor vacuum line connects.
(2) Poor spark (ICM, HV coil)
(3) flooding, like a fuel pressure regulator leaking fuel in to the vacuum hose
(4) low fuel pressure or low fuel delivery rate at higher rpms and loads

I have seen Renix run just fine with out a TPS sensor, except that it will have a flat acceleration spot at first if you gun the accelerator.

Good Spark, good fuel delivery, and a good MAP sensor signal are critical when you gun the accelerator on Renix. The key symptoms are good idle and back fire o when you gun it!

If it bogs down, when you slowly give it gas, and wants to die at higher rpms, you may have a blocked exhaust!

I have two 90s that ive rob parts off all used parts except cps and vac hose plugs wires cap rotor. Oh and map is new I had almost same problem on one of the others found it was map. Seams the same but switching between three map I think that's not the problem I put the map back on the other xj that runs good it work put on other same problem

So just to be clear, the other 90 runs fine?

OK, one thing you should test is the CPS cranking voltage with a volt meter set on AC volts and a scale just above .5 Volts (1-5 volt range). If you get less that 0.50 Volts AC then the new CPS is bad, or needs to be remounted closer the flywheel or flex plate!

So this little bastard hose cost me a lot of time and money but thanks to all the input I got it fixed up good now

Congratulations!! That's why we recommend fuel pressure tests so frequently.

Only needed the hose?

Thanks and thanks for the help I would have tested sooner but no test tool and the local auto parts rented it out I kept checking back and no go finle just primed it id put my finger on shader valve and no good pursuer. I'm not 100% if that was the ONLY problem due to all the stuff I replaced but peace or mind because I am putting this xj together for my niece first ride this way I should not have to go work on it every other day

It's good to have closure, and your hillbilly fuel pressure test served you well! LOL.

Lol yes it did