Fuel Injectors
 

Well now that its starting to get warm, its time to start working on the Z again. I am going to do some tests, but I believe that my injectors are bad. I am going to get the Accel if I do in fact need new ones, but not sure which ones to get.

What is the stock flow rate? My 92 is all stock short of a Samco air duct, so I wanted the stock injectors.

I cant seem to find what they should be.

Thanks

BTW for the guys who have used the Accel Injectors, how are they working?

Re: Fuel Injectors
 

Mine are working just fine!

Accel 150121 if bought individually, Accel 150821 if bought in packs of 8.
The best deal is from Atlantic Speed Performance Parts, $249.88 for pack of 8. Plus they send a nifty "Tee" shirt with your order. There might still be a discount if you mention the ZR1 Net Registry.
http://www.atlanticspeed.com/
You'll need Marc Haibec's special "O" rings if your Z is a 90-93 for the primary injectors.
http://www.zr1specialist.com

What makes you think that your injectors have gone bad? Have you measured the resistance of the injector coils?
No sense climbing under the plenum if you don't absolutely have to...

TomC
'90ZR1 #792
Honorary Pirate
http://i71.photobucket.com/albums/i1...ey5_pirate.gif

Re: Fuel Injectors
 

I just tested my injector resistance tonight - all seem OK. They were cold though, but all between 12.1 and 12.4 ohms. I'll re-test when hot.

(I'm having some loss of power on 2ndaries..).

If it's any help, I created myself this diagram to speed up figuring the stuff out from the factory service manual:

http://i158.photobucket.com/albums/t...esistances.gif

... it's not as complicated as it looks ... The first relay is easy to get to, the second may need small hands with the battery in place. The ECM of course easy to get to, and the Ignition Diagnosic Connector - as the manual says - is sort of lying on top of the big cable-bunch just by the wiper motor...

Re: Fuel Injectors
 

Very cool diagram!
I will be keeping a copy of it for future reference.

TomC
'90ZR1 #792

Re: Fuel Injectors
 

I am not sure that they are bad at this point but it is a guess.

After I replaced the ECM, it was running fine for a bit, but then I could feel a pretty major loss of power under load. When I got toward the top of the RPM range, it would throw a check engine light. I ran that code and it said "lean fuel" (I forgot which code it was).

I was going to be checking the resistance next on the injectors, just have not got around to it. I just wanted the part #'s in case they are bad, I can order then right away.

What is the flow on them, 24# primary and 19# secondary?

Re: Fuel Injectors
 

me too---nice of you to post it here c4koh


links for you to check out ff

injector tech page>>> http://www.rceng.com/technical.htm

http://listserv.corvettemuseum.com/c...zr1net&P=37183

http://www.flatlanderracing.com/accelfuelinj-gm.html

Re: Fuel Injectors
 

I hope that the reference diagram is useful! I've had so much help here (and on the previous listserv) over the years - by people who know so much more than me - that I'm glad to offer whatever I can!!

I remembered I checked out my injectors about 3 years ago, and checked them yesterday - and was just puzzled for about 1/2 an hour trying to figure out exactly what the service manual, the listserv posts etc. were trying to say...

Anyway, I decided to write it down - it will surely speed up the process for future...

Re: Fuel Injectors
 

http://www.autoshopracingengines.com/

432.00 for all 16. :thumbsup:

Re: Fuel Injectors
 

I had the same issue on my 90', turned out to be a bad fuel pump. Replaced both of them, problem solved. By all means check your injectors too, but I think you'll find the fuel pump is the issue. If you haven't already done it, replace the fuel filter before you do the fuel pump test. A clogged filter can cause the same problem.

Hans

Re: Fuel Injectors
 

I don't know the exact number, but the primary and secondary have the same flow rating. So it won't be something like 24 and 19.

FWIW, my injectors read fine too between 12-13 ohms hot or cold (read higher when hot). But they leaked. When I pulled the plenum I could see drops form on some of the injectors as they sat. Also before that I could let the car sit and sit and sit, and then crack the throttle blades open. You could really smell the gas vapors coming out.

I imagine the car made full power, though, the injectors weren't too bad. But idle, low rpm, and part-throttle driving was much smoother after replacing them. I went with Delphi '93-95 replacements on my '90. They were slightly less than RC's (and were available immediately).

Re: Fuel Injectors
 

They are 21#... doing mine soon, after I get moved into the new house in Chicago.

:cheers:

Re: Fuel Injectors
 

WELL-WELL LET ME WELCOME YOU TO THE WINDY CITY CC I KNOW IT WILL NOT BE THE SAME AS THE ROCKIES BUT YOU WILL ADAPT TO BEING A FLATLANDER AND WE STILL HAVE PLENTY OF SNOW AND COLD TO KEEP U FROM BEING TO HOMESICK!! LOL :cheers:

Re: Fuel Injectors
 

Looks like I won't be far from you, Bryan... I bought a place in Grays Lake.
:cheers:
Hans

Re: Fuel Injectors
 

if your engine light comes on at the top of the r range you could be having a secondary vaccume issue. i has your systoms and it was a leak to the manifold dif meter that sits under the ecm..it looks like a mapsensor:mrgreen:

Re: Fuel Injectors
 

Kool---I am puting a vette/radio guys party together for the last sunday in july rain date 1st sun of aug at the McHenry Dam. I'll be sure u get an invite! It was a blast last year but only the radio guys--this year we add the vettes! Afternoon cookout party type of thing!:thumbsup:

Re: Fuel Injectors
 

You could be losing your secondary fuel pump...basically you're running out of gas because the primary pump can't keep up wit the demand of all 16 injectors...works OK with 8...but 16 is to much of a load...that's why we have two fuel pumps. Make sure you remember to write down the code(s) you get when you get your SES light...so you can post them here...

Re: Fuel Injectors
 

Great minds think alike :handshak:

:cheers:
Hans

Re: Fuel Injectors
 

You guys posted some great thoughts on this issue.

I am going to do more testing before I say that the injectors are bad, that was just my first guess.

The fuel pump is a good thought too. Where do I start to test that? How can I determine if it is good or bad? I know someone posted it before but what are the part numbers for it, or should I say for that truck pump and the years for that truck pump that works?

Well my first step will be to get it running and take it out. I will see what is happening and see if it throws the light.

I did notice sometimes, it did not feel like it had full power and it did not throw the light, but a few times it did.

I was going to check the vaccuum lines but it appears that the hose is hooked up to the map sensor, but not sure if it is hooked up to the other side.

I will check this stuff out and post my results back here.

Thanks to all for the ideas and help.

Re: Fuel Injectors
 

If the SES light is a "hard" or stored code reading it will give you a starting point. The extra MAP under the ECM is used to verify vacuum to the secondary system and the ECM uses it to turn on the pump as a back up vac source during extended 2* operation, or low vacuum conditions like WOT.

Fuel, if the pumps are not up to it you could get a lean signal from the O2 sensors but I'm not sure if we are in closed loop during 2* operation if WOT is not achieved. 55 psi is the target figure in the KOEO test, and 48 to 55 with the motor at idle speed. Both pumps will run during the KOEO test, you have to pull either fuse to do the KOEO test on each pump. Test primary pump, then secondary pump after teasting both pumps in the KOEO test. You could discon the relays instead of the fuses as the 2*(?) fuse is up by the CDM box and a bit of a PIA to get to. I would change the F/F before doing the pump test.

:cheers:
Tom

Re: Fuel Injectors
 

Crap, you know, last year I tested the fuel pumps, but I forgot the readings I got.

I thought they were in the good range, but I will test them again first.

Unfortunatily, the car is not in a garage right now and its going to be raining all week. I will chevk into that when the weather clears up.

Dont worry, I am hopefully going to buy a house this year and will get a garage for it. I hate leaving it outside. But being single, it is hard to find a house I can afford nearby.

Re: Fuel Injectors
 

http://i119.photobucket.com/albums/o...white-zr-1.jpg

Maybe FF will come down for the party too--

"Kool---I am puting a vette/radio guys party together for the last sunday in july rain date 1st sun of aug at the McHenry Dam. I'll be sure u get an invite! It was a blast last year but only the radio guys--this year we add the vettes! Afternoon cookout party type of thing!"

Re: Fuel Injectors
 

Keep us posted!! I may have too

Re: Fuel Injectors
 

OK. Tested the injectors today. Here are the results:

Primarys: Secondarys:
#1 12.1 #1 12.1
#2 9.3 #2 12.3
#3 12.4 #3 12.3
#4 12.3 #4 12.1
#5 12.3 #5 5.1
#6 12.4 #6 6.0
#7 12.4 #7 12.0
#8 11.7 #8 12.2


From those numbers, I am going to guess I need some injectors.

I know when we tested the pumps last year they were within the specs listed in the shop manual, but cant remember what the pressure was.

Does anyone know if the Accel are stainlss steel? I cant find it on the description of the injectors. If not, I may go with the RC. I dont drive the car alot and I dont want them to rust.

Re: Fuel Injectors
 

I don't know much about the Accels. I would think if they were s/s that Accel would say that up front...sales gimmick & all. TCrabs & johnny phrogs used them...maybe a pm is in order? I do think that there is an o-ring kit from Marc that is needed for the early primaries to be replaced by the accels, but I could be off on that...I used the RC's when I did my 90...ya may want to check up on that too. Oh, Marc = zr1specialist.com = M. Haibeck.:o

While I had it apart I'd check the pumps again....I've bad luck when it comes to this "while we're here" stuff!:o But I think most of your #'s are nominal save for the obvious ones. Were those #'s cold or hot? Mine were easy, four of the 1* on the right bank just quit & all the 2* were gunked up @ the tips!

Not to make work for ya but ya may want to go thru the 2* vac system and check the alt & starter & coils & wires & the CCV box gasket....ya know the while we're here thing again! Only reason I say to look at all that stuff is that the gaskets are expensive and all that stuff lives under them. If something else breaks under there shortly after....well ya know.

Sorry to be so looong winded & not give any concrete answers!
:cheers:
Tom

Re: Fuel Injectors
 

Thanks for the info and you read my mind!! I was prob going to replace the vac lines and check everything else under there.

That test was all cold. I have not even run it this year yet.

Re: Fuel Injectors
 

The Accels are stainless steel.
You will need to buy Marc's special "O" rings for the primary injectors on the early year cars. $20 plus shipping.

If you're running a stock chip, yank it out and put in one of Marc's updated PROMS. You will not be disappointed.

TomC
'90ZR1 #792

Re: Fuel Injectors
 

OK, need a little clarification here. I'm about to replace all my injectors in 1990 #1507 with Accels ($27 each at Auto Shop racing engines). I called Haibeck about these o-rings and he said the info is a little misleading and I don't really need them. So now I'm confused. Any help?
PS: I'm a new Net Registry member.

Re: Fuel Injectors
 

Hmmm.......
I bought a set of Marc's special "O" rings when I replaced my stock injectors with Accels last year based upon this information:

This probably belongs on a web site but I didn’t have a chance to add it to mine yet but anyway here is my story….and warning this one is a long one....

I was already cussing like a sailor when I found out that that I needed to replace essentially all of the injectors on a recently purchased 1991. Then when I found out that that you really have only a few choices: original stock “crap” with the same flawed design, rewrapped originals (aka MSD, and not avail for “correct” primaries for 90-91), or finally, RC’s. Also notably, most reputable “Injector Cleaning” services won’t service the originals because of the flawed design where the cleaning process itself has been known to kill them. Yes, there are some interesting conspiracy theories that GM pushed through these injectors knowing they were flawed to begin with but I won’t go there. Anyway, back to the story. With all options in excess of $1000 for a set of 16, my cussing turned into kicking and screaming since that $1K would come out of my “MORE POWER” budget.

As longtime F-Body and L98 converts like myself can attest, a common mod/cost savings for standard TPI cars is to ditch the stock 22lb injectors in favor of the much cheaper “Motorsport”/Bosch style, so I started my investigation as to whether or not this would work on our Z’s. Initially, I came up with the same results as many before me. Bosch style can be used on the secondaries, but most are poor quality, and then you have mixed sets on of primaries and secondaries. Unfortunately they also don’t work on the 90-91 primaries thanks to the unique design with the O ring in the injector housing and the “offset” guide for the electrical connector clip. It is possible to “update” to the later style injector when used in conjunction with a larger O-ring in the injector housing but that only works with Lucas/Delphi/Multec style injectors that do not have the plastic end cap like Bosch do.

So, after all that research, I planned to suck it up and buy RC’s. When I called RC in December 2005, they were out of the 205cc primaries until late March 2006. Crap, now what. Many just bought their 210’s during this time, but I already have a Haibeck chip designed for 205’s. Probably wouldn’t be a big deal to use to the 210’s anyway, but I decided against it.

The plot thickens. It turns out Accel ditched their old style “Bosch” injector in favor of a new stainless steel body, Lucas style housing. You guessed it, it’s a comparable housing to that used by RC. Curious, I found a set of 8 “new” style Accel 21 lb/hr on eBay for $209, and since I had a few months, what harm is there in experimentation? When I received them, they did indeed look like a much higher quality unit than the old design, and knowing that the old style Accel units typically flowed more than rated, I sent them off to the very reputable Rich Jensen to get some flow numbers.

Oddly, they flowed almost exactly 19.4 lb/hr across the board for all eight. That’s really great for me, but potentially really bad for Accel, since they are rated at 21 lb/hr. If you do the math, 19.4 lb/hr * 10.5 = 203.7cc, almost right on the mark for what I was looking for.

I immediately purchased another set, yes on eBay again, and sent them of to Rich. To my amazement, Rich had the same results on the next set of 8. On top of that, the flow numbers for all 16 were so close I didn’t even need any “pairing” them to balance lower flowing injectors with higher flowing.

Now to make them work:
For the primaries, remove the lower O-ring on the new Accel units. Replace the existing IH O-rings with the larger O-rings from Marc Haibeck (~$20+ship). The lower O-Ring will seat against the slight taper on the Accel injectors (see photo). For later models you don't need the larger o-rings and needless to say, do not remove the lower o-ring.

http://img145.imageshack.us/img145/3...ies2lp5.th.jpgJust click for larger images...



Use a razor blade to remove the plastic guide for the injector harness clip.

http://img134.imageshack.us/img134/3...fiedxe7.th.jpg

http://img154.imageshack.us/img154/1...riesej0.th.jpg

Don’t worry, the guide is just that, a guide, the harness will still clip in place by using tabs on the sides. The guide was simply there so the primary and secondary were not swapped, but I’m not sure why they did that since it’s really difficult to stretch them to install them incorrectly. As for attaching to the fuel rail, simply use the original clip on the highest ring on the Accel unit(see pic above). Yes they do sit slightly lower in the rail but this does not impact sealing.


The secondaries work without modification.

What you need:

(16) Accel 21# fuel injectors PN 150121 ($228-$248 for 8 right now on eBay New In Box) I think they run ~ $280 from Summit

Large IH O-rings available from Mark Haibeck $20 (Sure you can probably get these elsewhere but Mark deserves the biz..)

Flow testing of your Accel injectors just to be sure… $5/injector

Total: ~$500


My 1991 is up and running in this configuration without any sealing issues on the injectors. I have yet to put it on the dyno to verify the A/F. My “seat of the pants o' meter” tells me they are working just fine, and yes, my seat is a very highly tuned measuring device. I am having a bit of difficulty with my idle a bit high but I’ve all but ruled out the injectors.

Take this info as you like. This is simply the way I did mine to save a buck, actually over 500. I will post more details on a web site when I have a chance but I wanted to pass along the info since “Injectors” seems to come up regularly.

I was hoping someone else might be as adventuresome and give it try to substantiate my claims….

To be honest, I didn't match up the originals to the ones I bought from Marc to see if there was a size difference. I just figured they were what I needed and was happy with that.

If Marc said you don't need them, then you don't need them. However, having said that, it would probably be prudent to call him one more time and ask him "Are You Sure???".
Marc is THE MAN and I would never question him on anything ZR1 (or anything else for that matter, but I digress). Maybe he's learned something since I replaced my injectors last year.

TomC
'90ZR1 #792

Re: Fuel Injectors
 

So the Accels are S/S?? I did not see that anywhere and was not sure. Does it saty that somewhere and I missed it?

As for a chip, I do have a DRM chip. I do not know the specs as I got it with the car. I know it gets rid of the 1-4 shift.

Other than the chip and a Samco air duct, my car is all stock and I was going to keep it that way.

If them Accels are S/S, I think I will get them.

Re: Fuel Injectors
 

I stand corrected. According to Uly (Guinessdude) the Accels are nickel plated as per his posting over at the CF:
TomC
90ZR1 #792

Re: Fuel Injectors
 

OK

So what is the opinion overall on which injectors I should get?

I dont drive the Z a lot so it has some sitting time. I dont want them to rust up and have to replace them in 5 years.

When I do drive it, I drive it hard. The secondarys are always open.

Re: Fuel Injectors
 

Welcome GH to the forum!:thumbsup: :cheers:

Re: Fuel Injectors
 

If it's to be a NCRS judged car, order up a set of AC Delco and live with the fact that you will replace them over and over and over.

If cost isn't an issue, the RC Engineering fuel injectors are the next most expensive and a lot of people have used them. Ask some of the builders/tuners out there what they think of them. Some use them, some don't.

The Accels are new, so far only a handfull of us have them installed, so there's no real hard supporting evidence on longevity or reliability.
My "Seat 'O Pants" dyno tells me that mine are working JUST FINE and hopefully will continue to do so for some time to come.
The price was right too.
Accel is a pretty big name, and I'm hopeful that if there's problems they will be helpful and friendly.

[rant ON]
AC Delco was NEVER helpful, friendly or stood by their product.
And they NEVER WILL.
The original AC Delco Multecs were (and still are) a flawed design from the get-go and because it was such a limited production run they never updated the injectors nor offered to replace them.
They're "Official Corporate Response" is:
"We designed them for the gasoline at that time, it's not our fault that you're putting bad gasoline in your car that ruins your injectors".

Don't get me started.... I spent hours and hours on the phone and trading emails from the flunkies at AC Delco.
Got me NOWHERE.
A complete waste of time and effort.
[rant OFF]

TomC
'90ZR1 #792

Re: Fuel Injectors
 

I agree, AC delcos will not be going back in the car. Just for fun, I went to the dealership to price them out, since I wanted to check on crate engines for another car, and they are still available at $180 each, thats over $2800 to replace all 16!!

I am mostly concerned about durability. I dont want to do this again int he next 5 years. My choise is between the R/C and the Accel, just cant decide at this point.

Re: Fuel Injectors
 

Yes welcome to the forum!!

Im not sure on that either. When I helped replace a set in Effingham last year on the 90, I believe we did use O-rings. I was going to order them just as a safe measure. But I would tent to believe Haibeck also.

Anyone else got the correct info?

Re: Fuel Injectors
 

I've spoken to Haibeck personally (and in person) about the o-rings, he says special ones are not required on the Accels or the RC's. I just ordered a set of Accels for my car, everyone I've talked to that put them in is happy with them. Just make sure thay are the new silver (nickel) bodied ones and not the older design yellow ones.

Hans:cheers:

Re: Fuel Injectors
 

I'm fairly sure the Delphi ones are visually indistiguishable from the originals. They are resistant to ethanol. Not too many people seem interested in going that route, but just wanted to toss it out again. :)

Mine cost me about the same as RC's would have. Though if you go with the '90 style primary it would probably be a couple hundred more as they were ~$20 more each.

Re: Fuel Injectors
 

Nice catch!!!!

Are all 16 the same? I thought they were different between primary and secondary.

Re: Fuel Injectors
 

Yes all 16 are the same. Put them in and go..

Hans:cheers:

Re: Fuel Injectors
 

I went to place an order with them and they dont show a payment type using a credit card without using paypal!! Idont have paypal.

I sent them a e-mail to see if they will do a credit card and no paypal.