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Renix motor running rich?

S

Slim35

NAXJA Forum User
Location
Wilmington,NC
I have an 89' Cherokee 4.0 and I noticed to day when I shut it down in the parking deck at school I could smell gas. There are no leaks that I could find but I used almost a quarter tank of gas only running 20-25 miles. Im assuming its running rich because of the smell it runs perfect drives fine and last week I got 19mpg on 31s and 3.5iknch lift stock gears. I have put upgraded Bosch injectors in it (which helped alot) new plugs cps is fine just fixed it maybe 2 months ago. Only thing I dont have on the Jeep that I know of is a cat (was like this when I bout it) havent been able to put a new one on it yet but will in the future. So what could be causing this issue.
 
I would check under the jeep all the way back to the gas tank for a leaking hose under pressure.
 
Also, pull the vacuum line to fuel pressure regulator and see if there is gas there. If there is, the regulator is bad. Sounds to me like leaking fuel line from the tank to the fuel rail.
 
Ya im starting to think theres a fuel leak on my way home with just the driverside window down I could smell gas when I accelerated a lil. Where is the regulator at and should I invest in an adjustable one if it needs replaced?
 
Adjustable regulators are quite expensive and not really needed unless you are building a turbo.
 
It is vacuum adjusted already. It is on the front of the fuel rail, with a vacuum line attached.

Find the leak before you drive it again and go BOOM!!!!
 
If you are really consuming that much gas, it would be hard to even keep the engine running and you would see a significant black cloud out the tail pipe. Leaking that much gas isn't all that hard. Look under for a clean spot on the bottom where the Jeep rust proofing (oil) has been washed away. If you turn on the key, you should hear the pump pressurize the lines and you should be able to see/find the leak.

Now if you mileage has simply gone to hell, check the lines to the MAP and the MAP itself, or a commonly overlooked sensor, the Air Charge Sensor.

Personally, I am old school. I would pull the plugs and do a visual on them. Do a bit of searching. Plug reading tells you the world about what your engine is doing. With computers, it seems to be a lost art.

Good Luck
 
I agree!!
 
Wen i did the plugs number 5-6 they were a lil black guess ill check em again. It has also started to run like the head gasked is blown only wen at idle but wen i rev it up it does fine. This morning it shut down because it idled so bad right after starting it. Started it again and didnt have any problems after the second start up. No oil in the coolant and no coolant in the oil. Im lost.
 
Did you check the Vacuum connection on the fuel pump regulator for a gas leak while the engine is running?
 
Time to do a compression test.

Is there a greasy film on the rear window?
 
Slim35 said:
What should I be looking for when I do this?



No there is not a greasy film at least not that I have noticed.
Click to expand...

Look for liquid gas, and gas smell at the vacuum male nipple, on the FPR. Make sure the engine is running.

You also might have a fuel injector sticking open.
 
Ecomike said:
I would check under the jeep all the way back to the gas tank for a leaking hose under pressure.
Click to expand...

X2 -Have a look underneath while it's running. I pin hole size leak in a fuel line or connection can spray so fine it's hard to see but you can usually smell it and sometime feel it. The metal fuel lines often start disintegrating so look along the frame rail on the drivers side down towards the gas tank. I had a suburban that smelled like gas but you couldn't really see any drips on the driveway. When I ran my hand along the fuel line, I felt the mist on my hand. Had to redo a long length of line to fix.
 
Its holding fuel pressure as far as I can tell parked it at school for 3-4 hrs and push the pressure releas valve and gas came out so Im asumeing my new injectors are fine.
 
Was talking to a guy at the parts store whos got an xj and he mentioned the map sensor may have something to do with it running rough once in a while and uusing more fuel. He also mentioned the odler xjs fuel guages didnt work quit right either. Is it possible that this would be the issue and can the map sensor be reset or something to try and help the issue
 
the fuel gagues work just fine as long as the sender in the tank is good and the grounds are good.

I'd check the map sensor and the intake air temp sensor.

and the coolant temperature sensor in the side of the block, as it tells the ECM when the motor is warm, and thus wen to drop into closed loop operation.

same with the O2 sensor.
 
The reading on the needle type fuel gauge in the Renix years is notoriously non-linear. I drive the same 45 miles each way to work every day. From a full tank, I can make it 4 days. I have pretty much a half tank after three days and the last day it goes to from half to zero.
 
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