New FIC injectors
Thread Starter
Pro
Joined: Oct 2012
Posts: 648
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From: weems va
New FIC injectors
Just installed new injectors in my 93. All went well. But now i have a small popping,backfire that i never had before. Its not an even steady popping noise. Not very loud and it seems only at low or midrange. The idle is a little rough. I had changed fuel filter,plugs and wires about 300 miles ago. I have to crank it for 5 or 6 secounds to start, but with the new injectors i dont get the white smoke that smells like gas when starting. I dont think i missed anything when i did the injectors but? Any ideas where to look? Fuel pressure regulator,EGR valve? Thanks Dave
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Check to see that you have the firing order correct on the plugs. I would guess that you do. Next check to see that the plug wires are tight on the plugs.
Can you check to see that you don't have a bad injector plug? Are the plugs on the injectors tight?
Can you check to see that you don't have a bad injector plug? Are the plugs on the injectors tight?
Thread Starter
Pro
Joined: Oct 2012
Posts: 648
Likes: 6
From: weems va
Plugs and wires were done a while ago and didnt have problem. Might have loosened a injector wire/plug when i put covers back on rails? The problem didnt start till i put on new injectors. Ill back track when i get home assuming the injectors are good( I hear nothing but good things about Jon at FIC) im not worried if i have to return them. Dave
Thread Starter
Pro
Joined: Oct 2012
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From: weems va
When i got home last night i started her up. A little hard starting but NO white smoke like i had before installing injectors.Got it up to mid way temp and it had the same light back fire/popping exhaust sound. I revved it some and thats when i noticed it,not ver bad but you can hear it and it hasnt happened before. I check all the injector plugs and the all seemed tight.No fuel leaking.Could i have allowed raw gas to drain into the crank case? The dip stick is on the high side.No popping when i 1st start it but as soon as it heats up it starts. Dave
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Since the fuel injector replacement on an LT1 is so easy, I would take everything apart and check again.
Use Dish Soap on the O-Rings instead of Oil or Vaseline as Jon Banner says in the instructions and push the injector straight down without twisting. Install the bottoms first, then bolt on the top fuel rail.
Use Dish Soap on the O-Rings instead of Oil or Vaseline as Jon Banner says in the instructions and push the injector straight down without twisting. Install the bottoms first, then bolt on the top fuel rail.
Last edited by GKK; Jun 6, 2013 at 10:37 AM.
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Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
...so i bought a Actron tester from advance and will hook it up for the first time asap.
You might also check engine vacuum at idle to verify that all vac lines are in tact and attached properly.
Instructor
Joined: Jul 2011
Posts: 166
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From: Chardon Ohio
Subscribed -- Same issue since early 2012. Have replaced TPS, Opti, Plugs, Wires, MAP, Cool Temp sensor, o2 sensors, intake temp sensor, fuel pressure regulator, pcv valve, cleaned throttle body, reset lash on roller rockers, new MSD coil, had the car re-tuned twice by PCMforless, replaced a couple fuel injector connectors, and about to purchase an ICM to add another to the list of unneeded parts installed. Lots of money wasted to solve this issue.
Thread Starter
Pro
Joined: Oct 2012
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From: weems va
I checked fuel pressure last night and its not holding. Hooked up tester turned ignition on got a 40lb+ reading and it dropped fast! Started car and it held at 40. Shut it off and down it went. Going to pinch return line to tank,looks like fuel pressure regulator. Jon and all my forum brothers have been alot of help.I have never fooled with injectors before. Im one of the old carb/dinos! Dave
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Hooked up tester turned ignition on got a 40lb+ reading and it dropped fast!
You can clamp pressure or/and return lines at the pump assy.
You can run jumper between ALDL pins A & G (??maybe on '94) to run the fuel pump for testing.
Thread Starter
Pro
Joined: Oct 2012
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From: weems va
Ok it was a few things. It turned out the FPR was bad replaced it. Now the fuel pressure was holding steady when i shut her down. I still had a miss. Last night when it got dark i started her up and sure enough i had a plug wire loose! And it was the plug closest to the firewall on drivers side. I got the plug wire on and its running great. Im going to change the sock next week end i found out that the fuel gauge is off. When i put 5 gals in an empty tank it shows half full or half empty? Anyway im on a roll cause this car was sitting sooo long up till this past Oct who knows what is in the tank. Cant say enough good things about Jon at FIC he walked me through the new injector install start to finish. Dave
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St. Jude Donor '12
When you pull the pump assy out of the fuel tank - inspect and clean the copper wires for the sender. Then use an ohm meter and move it through its range (IIRC should be 0 - 90 ohms) if its not you can add a resistor to bring it back. There are several old posts on what to look for and how to clean the wires and how to calculat the resistance for an additional resistor. Don't break or otherwise damage the thin copper wires!