Having some troubles with my ‘89. Has a 4.0 w/5 speed, fresh oil change, rebuilt fuel pump assembly, new injectors, cap, rotor, vac lines, plugs, and tps. Need some brake work and the throw out bearings makes some noise. Runs and idles great. As soon as I push in on the clutch and put it into gear it starts to fall on its face, stumbles, back fires, and I have zero throttle response once I put it into gear. Anyone on here have any experience with this issue? Fuel pressure is around 27-30

 

It stumbles as the clutch is let out, or literally when the transmission is in gear and the clutch pedal remains pressed? New TPS adjusted to 17% of reference voltage? Fuel pressure should be 31 PSI at idle and 39 PSI at idle with the vacuum line removed from the fuel pressure regulator (FPR).

 

clutch pressed and shifted into gear. I’ll recheck fuel pressure it’s been a few months since I checked it and it may be up there around 39. I know I had looked up what fuel pressure was supposed to be and it ended up being within the parameters.

 

Check your base idle with a scanner. It's likely too low. When you push the clutch in, the load makes it stall. Set it to spec with the IAC unplugged, then plug the IAC back in.

Also, double-check your TPS voltage and make sure it's set correctly. A bad signal there will kill the throttle response.

 

Is there any background on your XJ, when did it start doing this?

 

as soon as I got it running. I bought it as is with the information that it needed a fuel pump.

 

I can’t hook my scanner up it’s pre obd-2

 

So it is a mystery. Do you have a multimeter? I am still curious about what the TPS is set to (and the actual fuel pressure). I'd start with:

Renix TPS Adjustment | cruiser54

Renix Sensor Ground Test | cruiser54

Throttle Body to MAP sensor hose fix | cruiser54 When I did the MAP sensor mod, I just used standard vacuum line between the new throttle body fitting and the MAP sensor itself.

 

I need to do the hose fix anyway, it’s busted and missing half the vacuum line.

 

That could be a majority of the problem then. If you're not familiar with the RENIX, once you get these problems sorted out, it is a fairly solid engine management system.

 

These engines are new to me

 

Got vac line from map to tb fixed (didn’t change anything maybe made it worse but that could be me or due to it being a colder day), running 30-31lbs fuel pressure at idle and jumps to 39 when vac line is pulled from regulator. My voltmeter only reads to whole number. Input said 4 and output didn’t even show a volt.

 

Excellent on the fuel pressure, that is right on spec. You're going to have to find a way to read the voltage down to the hundredth to adjust that TPS - there really is no way to even try a guess at it. It's probably a good sign that the engine is running a little different with the MAP connected to vacuum, it should steady up as the rest of the sensors, and perhaps grounds, get cleaned up, although we haven't looked at compression...

 

The only noticeable thing having the map hooked up, is now when I put it into gear it dies.