Okay, this is my luck. Yesterday both of my Cherokees decided to be pains in my rear. Both are DD so I need to fix be this evening. I tried to search but all I have is my phone and it say can something the remote site. I don't know?? I really just need to verify a few things.

First the 94, it wont start. Cranks over and over, and doesn't start. I have some fuel pressure but only at around 15. I'm pretty sure I need a pump. BUT what throws me off is the relay is clicking none stop after I try start it. Does it with any of the relays I put in. So would the bad pump make the relay go batty??

The 90. After the no start in the 94, we jumped into the 90 went into town. On the way back something didn't seem right. I looked in the rearview when I was on the gas and it was smoking pretty bad. I got it home and its black smoke. So its running rich?? Most likely an O2 sensor??

Thanks for any help. This weekend has not been the greatest.

 

15psi on the fuel rail is not enough, if you have a set of noid lights you can check for injector pulse. check spark as well just to rule out the CPS. I forget exact spec. but the presure at the rail should be around 45psi.

 

Just went out to check the 94 again. It started right up. The fuel pressure is at 31 and with the vacuum off the regulator its at 40. I know the 90 pressure can be in the 30 range but the 94 is should be higher??

 

Both are the same fuel pressure.

Check the 90 to see if the hose froom the throttle body to the MAP sensor isn't cracked, unplugged, melted etc. MAP seeing low vacuun will make it run pig rich and smoke black. A CTS or IAT can do the same. O2 is not gonna cause your black smoke.

On the 95 you may have a bad hose inside the tank from the fuel pump to the fuel module causing some intermittent fuel starvation.

 

Thanks cruiser. Will check that on the 90.

On the 94. Why would the relay make the continues clicking nose? When it was doing that the pressure was around 15.

 

Pump hanging up? Bad ground for the fuel pump at the back of the Jeep?

 

Cruiser you are a life saver!!! At first I thought there was no way the vacuum hose was clogged or cracked on the 90. Its brand new!! So I just looked at it because you said to check it. I guess when I put the new one in, it was to close to the manifold and was almost melted shut. Put a new one on and the black smoke went away.

I will start on the 94 checking those things.

Thanks again. You are the man. Can I have your direct number to save me some time. Hahaha

 

I love simple solutions!!

 

Yes they are the greatest. I kind of freaked out when both of them went down on me. I was Thinking worst case.

 

How old is the battery in the 94?

 

One year old red top optima. That's a good point I will check the voltage. Thanks for the idea.

 

The battery sets at 12 when engine is not running. When running its high 14's. So I think I'm good there. Now I'm not very good at electrical stuff. Does anyone know what the voltage should be at the fuel pump plug? And I did the continuity check at the plug and the volt meter beeps at me on both outside plugs. When I put a probe in one outside one and one probe on the frame rail I get a beep. Same for the other outside plug. So I have two grounds?? And the center is my power??

Edit: Or I don't know what I'm doing. Ha

Okay I'm looking at my chilton schematic. Following wires after the fuel pump relay. They go to the ballast resistor bypass relay?? And the ballast resistor?? I know my 90 has the ballast resistor on the left apron and is ceramic. Where are they at in the 94. And how to check them??

 

Power to pump is one wire, ground for pump is other wire, varying ground to gas gauge. Check resistance from ground to frame rail. Sender will not be 0 but fuel pump ground should be.

 

Try to bypass your ceramic resistor.. I used a 15 amp fuse and it worked good.. That was a test after buying 2 resistors.. I just left the fuse there and dont use resistor..

 

I don't think it has the ceramic one on this year. If it does its not where my 90's is?? I thought they did away with the ceramic ones in 91. I maybe wrong.