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Mustang 19# Injectors, Backfiring Initially, Now Wont Even Start.

8

88XJSport

NAXJA Forum User
Location
Michigan
Changed my old Injectors to 19# Mustang injectors today, and once I got everything buttoned back up, I fired it up, took a few cranks, but finally fired. Once I gave it throttle idling, it would backfire, but after a few minutes, that cleared up.

Then I go to drive it, throw it in drive, hit the gas, and it backfires. I put it in reverse, same thing. I tried it again, and it was fine. Now I get onto the main road, and it has a hard time getting into second gear. First gear is fine, but when it shifts to second, there is a power loss. I push the pedal, and nothing happens, I dont seem to speed up as fast as 2st gear...pedal is in the same position. Until Ive pushed it far enough, it will go back to first gear and to redline. If I let it lag in second like it does, it will shift to third, and 4th...everything is fine, except second gear.

Bring it back home, shut it down. 5 Minutes later it just cranks and sputters. I checked one plug, and it seemed ok.

Anyone with a Renix run into this before?
 
Hopefully you didn't accidentally swap adjacent injector harnesses(1&2 and 5&6 esp). How'd it run before injector swap?
 
sounds like your getting way too much fuel and not enough air, I'm running a newer XJ but if I recall the renix are carbed right?? So maybe you need a bigger carb....Might even want to mess with the gaps of your plugs.
 
So the countless threads on here about 19# injectors for a Renix XJ are wrong? Everyone is boasting about how 19# injectors helped their throttle response, MPG's, and everything. I labled the connectors, those are not screwed up, and it ran fine before the swap, except for the fuel leak.

Keep in mind I drove it for 5 miles before I shut it down...it had a backfiring problem at random, but I was still able to start it until it decided not to.


Spark Plugs are dry BTW.
 
Last edited:
88XJSport said:
So the countless threads on here about 19# injectors for a Renix XJ are wrong? Everyone is boasting about how 19# injectors helped their throttle response, MPG's, and everything. I labled the connectors, those are not screwed up, and it ran fine before the swap, except for the fuel leak.

Keep in mind I drove it for 5 miles before I shut it down...it had a backfiring problem at random, but I was still able to start it until it decided not to.


Spark Plugs are dry BTW.
Click to expand...
im running motorsport yellow 19lb injectors in my 1990 and have had no problem i replace the o-rins when i did them and adjusted the tps sensor, but not being able to run with the renix system is not true i still get 15to 18 mpg with my daily driver from what i understand stock injectors are 16 to 17 lbs
2s963gh.jpg

11t6901.jpg
 
jeepxj1990, you may be onto something. How far off was the TPS when you had to adjust it? In other words how far from .83 was it???
 
Check and re-check the injector harness. It is easy to swap the cables between the injectors.

Did you use new injector connectors? Check the connector type are correct and fit the injector tight. I am using the same injectors. I also had the same problems that you do. I had to squeeze each connector (wire harness) with a needle nose plyers to get them to fit the injectors properly.

Next time I have to change injectors, I will buy the harness connector and splice them in. That would have saved me plenty of frustration.
 
Hello Mr. 88, Have you checked the firing order on your spark plugs?
I have installed the same injectors on my 1988 with no problems, actually it runs better than before. If it helps any, the firining oreder is: 1,5,3,6,2,4. good luck. Olaf
 
techno1154 said:
Check and re-check the injector harness. It is easy to swap the cables between the injectors.

Did you use new injector connectors? Check the connector type are correct and fit the injector tight. I am using the same injectors. I also had the same problems that you do. I had to squeeze each connector (wire harness) with a needle nose plyers to get them to fit the injectors properly.

Next time I have to change injectors, I will buy the harness connector and splice them in. That would have saved me plenty of frustration.
Click to expand...

Sqeeze the long sides or the shorter ends?
 
Where did you get the injectors? Were they new? Double check all of your vacuum lines making sure they're plugged in correctly.

I got a set off of ebay. They work fine in my 88.

JeepEngineBay003.jpg
 
I swapped these in on my '88 XJ with no problems. Plug and play. Check the firing order and the connections to the wiring harness. The OEM injectors were something like an 18.6 lb injector.

I won't say mine made mine run any different, but they kept it from turning into a flaming heap!
 
The injectors are brand new. I will check the connectors, making sure they are on the correct injector, and will check vacuum lines again.

Would not disconnecting the battery cause my problem? Stupid I know, and I realize Renix does not store memory, but Im thinking since I havent disco'ed the battery from the old injectors, that it could cause problems.

Thoughts?
 
jeepman121 said:
sounds like your getting way too much fuel and not enough air, I'm running a newer XJ but if I recall the renix are carbed right?? So maybe you need a bigger carb....Might even want to mess with the gaps of your plugs.
Click to expand...


fuel injectors and a carb????



88xjsport,

when i replaced the injectors on my 89 with new out of the box injectors, the engine spit a popped for the first mile or 2 and then all of a sudden it cleared up and ran perfect.
 
vacuum line on the pressure regulator? It's easy to miss reconnecting it and that could give you a lean backfire if it's allowing fresh air into the intake. Double check other vacuum lines as well-- MAP. CCV, etc.
 
After further investigation, I ordered Mustang injectors...but they ended up being 97 3.8 V6 injectors. A website I googled, told me that those injectors are 15# not 19 like I thought.

So now it makes it easy...engine is starving for fuel, poundage is too low, and Im embarrassed as hell. :looser:

Off to find stronger injectors. Sorry for the confusion.
 
89xj said:
fuel injectors and a carb????



88xjsport,

when i replaced the injectors on my 89 with new out of the box injectors, the engine spit a popped for the first mile or 2 and then all of a sudden it cleared up and ran perfect.
Click to expand...
LMFAO!!! I can't believe that just happened! I was skim reading and was not thinking :roflmao:...I had a buddy with an AMC Eagle that had carb issues and it BF'd and chugged. Uhhh, yeah, just go ahead and disreguard that last comment of mine!
 
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