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Bad fuel injector

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6K views 31 replies 10 participants last post by  96Lt1civi  
#1 ·
Hello! My 96 caprice recently developed a miss on cyl #7, and I narrowed it down to the injector for that cylinder.
I decided to try and clean all the injectors with a diy cleaner that works pretty well. However the no 7 injector leaks pressure when off and only intermittently clicks on. When it finally does, the spray is not as consistent and clean as the rest.

To fix this should I just get a working one from the pick and pull and clean it, or just get a new set or one new one?
 
#2 ·
you can have injectors serviced/rebuilt for less than $20 per injector.

I use www.cruzinperformance.com

its a mail them the injector(s) thing. They send a B/A flow chart to show wat the difference is after service

If you pull one from junkyard, you want it to be the same 24 lb one you have

even though there are other 24 lb injectors to buy you want the same kind you have as pulse rate and spray pattern vary between brands
 
#4 ·
If you pull one from junkyard, you want it to be the same 24 lb one you have
even though there are other 24 lb injectors to buy
you want the same kind you have as pulse rate and spray pattern vary between brands
Good news is there are better 24lb per hour injectors out there, AND, there are larger injectors out there that can idle better than mid-'90s LT1 24lb per hour injectors.
But if you got 'different' injectors with the same flow rating, I don't know who could possibly program properly for them.

Ideally you want your injectors to be as close to octuplets as possible, though that's rare.
Far more common is a pair of quadruplets.

I invite ANYone to explain this better than I.
 
#3 ·
#6 ·
 
#9 ·
Sorry I'm late, been busy shipping injectors. Unfortunately I don't have the ability to tune 96 PCMs at present, but I'm working towards it (probably a few months out). In the mean time, you could search out junkyard injectors and you may find some usable ones. Be very sure to check part numbers, as I accidentally sent some L99 4.3 19lb injectors because I didn't pay close enough attention. As I wrote in my thread, after sending two sets to WitchHunter and barely squeaking out with one good set, I was done with the stockers.
 
#11 ·
The junkyard over here has them for $10. I figure it's worth a try.
Fortunately I know how to tell the difference betwixt the the two engines.

Do the Lt1 injectors have a different part number than the L99 ones?
Because I have some injectors laying around that I think are for the L99, but I'm not sure.
 
#12 · (Edited)
The junkyard over here has them for $10. I figure it's worth a try.
Fortunately I know how to tell the difference betwixt the the two engines.
Just so you know, I've personally witnessed 5 cars that should have had LT1s that actaully had L99s.
I know one was intentional.
Whether the others were mistakes or trickery, I never found out.
Do the LT1 injectors have a different part number than the L99 ones?
Because I have some injectors laying around that I think are for the L99, but I'm not sure.
By definition, a 19lb per hr injector and a 24lb per hr injector must have different part numbers
(because they have different specs).
 
#13 · (Edited)
EDIT - GM part number for the 19lb injectors is 17120683. Mistakenly I had called this the 24lb injector part number.
GM 24lb injector P/N is 19244617.
 
#18 ·
Sweet! I know for a fact that the extra ones work well, so I'll run that one until I decide i want new ones.
Thanks for the help!

Also, since the part numbers are obsolete, would I correct in thinking that they are likely original?
 
#19 ·
Yes.

And I edited my post above. The 17120683 were 19lb injectors.

For what it's worth, injector "refurbishing" is really just cleaning and replacing o-rings and the filter basket. It's not like they replace the windings or pintle or anything like that.
 
#22 ·
I'm also chiming in late, but I still daily drive a '94 Caprice and a '95 Caprice. Plus I have '95 Impala SS and '95 Wagon. I actually have the most problems with the Impala since it sits the most. That's what seems to hurt the injectors. That and they all have seen their share of bad fuel.

Myself and friends have had injectors serviced by Rich at Cruizin Performance (already recommended earlier in the thread). I can vouch for him. Very reliable and affordable (under $200). He sends you a performance chart outlining each injector before and after. Well worth the expense. I always send him a few spares with my order just in case one cannot be recovered. But so far, he's been able to bring them back to life without needing the spares. I have not encountered the permanent ethanol damage, at least not to the extent that the injector could not be brought back to life so far.

He's very knowledgeable about getting them working perfectly again. Not just some random shop who will run them through a generic cleaning cycle and say "oh well".

Looks like he has limited work hours these days, so be sure to reach out to him to set expectations on turnaround.

One note: if you live in the rust belt, he also cleans up the injector cases. But they will flash rust with the first winter road salt spray. I recommend taping them off and spraying the silver part with a layer of clear coat as soon as you get them in. Or live with the surface rust.

A few years ago I tried the guys on eBay who will sell you an entire "new set" of "equivalent" injectors for $100. Nope. Junk. Don't be fooled by the cheap prices. I am pretty sure they sent me refurbished ones, not new ones. And they weren't even the same style GM ones that belong on the car. The injectors will run the engine. But not happily. The engine ran rough at times with them, so I checked using a scan tool and the fuel trims were way off. As mentioned earlier, needs a reprogram to be reliable. I sent them back. At least the seller was nice about it and refunded my money saying "he's never had a problem before". Uh huh. OK. Since then, I vowed to always use the correct part number injectors on the LT1. I'll just keep sending them to Cruzin. He'll bring them back to life or let you know if you need any replacements.
 
#23 ·
Hello! My 96 caprice recently developed a miss on cyl #7, and I narrowed it down to the injector for that cylinder.
I decided to try and clean all the injectors with a diy cleaner that works pretty well. However the no 7 injector leaks pressure when off and only intermittently clicks on. When it finally does, the spray is not as consistent and clean as the rest.

To fix this should I just get a working one from the pick and pull and clean it, or just get a new set or one new one?
For 110 dollars after sending back the old injectors at Atlanta auto parts on ebay item#283538734938 it's a upgrade OEM Rochester 17095004. You'll be glad you have purchased it.
 
#25 ·
Why not try one used junk yard one if you are on a budget? Then check the fuel trims.

The OEM injectors are slow to open compared to the newer "Bosh style"(thin) injectors. My personal experience is the Bosh are hard to tune for a idle on a stock car. Mine idles but is rich.

Some of the used cleaning vendors care and offer warranty on the parts they sell. Due to brokerage fees at the border I have been asking and getting matched sets of ten. If one fails I have a spare. To me this is cheaper than all new but still has reduced risk. The guy I have been using sent me three replacements for no charge when I showed him pictures of scratched plastic on the injector bodies. He asked for some information on the paperwork so he could trace my injectors back to quality control. His policy is to reject some of the injectors for cosmetic reasons.The most mileage I have on any set is 30 000 miles and they are fine. The other car has less but no problems with them except for the PCM tune.

Injectors are electric solenoids that control fuel. My personal opinion is that under normal conditions they will be plugged by fuel contaminants long before other problems. If the vendor changes the fuel filter and pintle cap on a flow tested injector and provides warranty it should be a option verses a expensive new one.
 
#26 ·
I let car sit for a few months, which I'm sure has caused this.
Also ever since I got the car all of the fuel pressure bleeds off in about 10 sec. After seeing how badly the injector was leaking fuel, I'm thinking its been a problem for awhile.
My dad has an l99 in his garage that I got another injector from, since it ran great when he pulled it.

Cause he has a 95 Lt1 9C1 that had an l99 swapped in, but with lt1 parts, intake, injectors, ect. It even had an lt1 tune.
 
#27 ·
As I wrote in my Injectors For Sale post, if you just change the flow rate but not the short pulse adders and voltage offsets, the car will run fine with high duty cycle, but starting, idling and part throttle fueling will be off. Good tuners who had access to other GM BINs could use things like L67 and LS injectors and get the full characterization data out of those BINs, but I searched tons of aftermarket injectors and could never find the complete tables needed for any of them to be properly characterized. As Paul Yaw (Injector Dynamics) writes in Marky Dissod's links above, Ford's injector characterization scheme is far more simple and elegant than GM's, and Ford Racing does publish a lot of data for their injectors. I have no idea what Chrysler does for theirs, nor any of the other manufacturers.
 
#29 ·
I swear I hear “If you have enough time to do it twice,, just invest the time and do it right the first time!” Every time I read one of these posts. LOL. No offense intended - some schitt my dad would say whenever I tried to cut a corner...

buy new set of 30# injectors (stock is 24#) and call it a day.

Hello! My 96 caprice recently developed a miss on cyl #7, and I narrowed it down to the injector for that cylinder.
I decided to try and clean all the injectors with a diy cleaner that works pretty well. However the no 7 injector leaks pressure when off and only intermittently clicks on. When it finally does, the spray is not as consistent and clean as the rest.

To fix this should I just get a working one from the pick and pull and clean it, or just get a new set or one new one?
 
#31 ·
Hello! My 96 caprice recently developed a miss on cyl #7, and I narrowed it down to the injector for that cylinder.
I decided to try and clean all the injectors with a diy cleaner that works pretty well. However the no 7 injector leaks pressure when off and only intermittently clicks on. When it finally does, the spray is not as consistent and clean as the rest.

To fix this should I just get a working one from the pick and pull and clean it, or just get a new set or one new one?
Everyone is right about ethanol corroding fuel systems, including fuel injectors and fuel pumps. Bs sure to add ethanol treatment, such as Sta-bil marine 360, to the fuel at each fill-up. Any vehicle before 2007 is very susceptible to ethanol corrosion. I use ethanol treatment in all my vehicles, including the new ones. Adding ethanol to gas was one of the worse mistakes the government made.