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Renix Stumped

indyjeepnut

indyjeepnut

NAXJA Forum User
Location
Greenwood, Indiana
I am putting together an 89 MJ that has been sitting for 3 yrs. The problem I am having is that it keeps fouling the plugs on start up. I have replaced the following, cap, rotor, plugs, plug wires, and O2. If I put a fresh set of plugs in it will fire rite up and run but the next time it will crank and crank and then foul them. What I am calling fouled is black and wet.

Any help would be appreciated. I am trying to get this thing ready for winterfest and It's not looking to good.
 
I would double check the coil, cps, cts, map and the fpr. You might want to try a step hotter on the plugs, you obviously have another problem but it might help. A champion 346 or an Autolite 3926 are a range hotter and readily available. Also is the gas fresh or three years old?
 
CW said:
I would double check the coil, cps, cts, map and the fpr. You might want to try a step hotter on the plugs, you obviously have another problem but it might help. A champion 346 or an Autolite 3926 are a range hotter and readily available. Also is the gas fresh or three years old?
Click to expand...


I took a coil from another 89 cherokee and the same result. I will pick up come chanpions tomorrow. I am not sure of the # on the champions that I have but they fouled also. I have 40lbs of fuel on the rail If that matters.

Thanks
 
seconding the fuel pressure regulator. even if it's not leaking through the vacuum hose it could still be stuck open. possibly the map, but fpr seems more likely.
 
jneary said:
check the fuel pressure regulator. if fuel leaks from the vacuum port, it is bad
Click to expand...

X whatever, it is getting too much fuel or not enough air for some reason. Could also be a leaky injector. I would think its more fuel related than spark and air. Also make sure the IAC port is as clean as you can get it to allow the proper amount of air to flow through it.

Are all of the sensors plugged in? If either the CTS or MAT are unplugged(or not working/out of range) it will be full rich on start up.
 
All sensors are plugged in I think. I will triple check tomorrow. I will also swap the FPR from anothe working renix to check that too. I have checked the IAC and it is clean.

Anything else?
 
Try cleaning the injectors. If you have to, remove them and soak the pintle ends in acetone, then brush lightly.

Gasoline turns into something between varnish and shellac when it sits for too long, and I've run into this sort of problem before. The varnish will either close the pintles (meaning no fuel) or stick them open (meaning far too much.) Sounds like the latter case for you.
 
CW said:
I would double check the coil, cps, cts, map and the fpr. You might want to try a step hotter on the plugs, you obviously have another problem but it might help. A champion 346 or an Autolite 3926 are a range hotter and readily available. Also is the gas fresh or three years old?
Click to expand...

I went to NAPA and they said champion 346 is not a valid number. I crossed autolite 3926 and it came up champion 344. That is what Napa's computer say's fits renix. Is that what everyone is running?
 
The 344 is the stock heat range plug, I sell the 346 and my work I don't know why they didn't get a valid number and the autolite crossed back to a heat range lower. :dunno: I can't remember off the top of my head but the part number on the champions is like RC10YC4 vs the stock RC9YC. We stock both of those plugs. I run the hotter autolites because I do mostly short trips in town with my dd and they seem to work better.
 
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