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Discussion Starter #1
I have a '75 Z. I have pulled the fuel injectors to clean them. I have had my car since 1999. I would have assumed the injectors were original but I am thinking they are not now. In looking at the hose from the fuel rail to the injector it says GERMANY on it. I am thinking maybe these are Bosch injectors? They don’t seem to have any O rings but down by the outlet of the injector there is fairly wide “O” ring. Anyone know what these are? I’ve included a pic of them.

Next question would be are these good injectors to keep and behold or should I think of something else.

Thanks,
GT
 

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Mr.GT75Z:

Well, the Z was built with a version of the Bosch L-Jetronic fuel injection system. However, I suspect the (metric) hose was installed in service.

Beyond that, I'm unclear about just what is your question. Is there some reason you wouldn't use your injectors? The seals are available in the aftermarket. And you're only a couple of searches away for tips on reconditioning the injectors.

Or, if you've money to burn, you could replace them all.

The adventure begins...
 

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O-ring is present, its that wide band around the mid section of the injector. What you see missing is the pintle cap. One reason being these may have been replaced at some point with non oem injectors.
 

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Discussion Starter #4
I recall that now, the fuel injection system was a Bosch. I have cleaned three of them so far and they all seem to work fine. I will do the other 3 today. Plus the cold start injector.

My question about the O rings is that I only see the small O rings after pulling the injectors (assuming the small O ring is the one at the bottom (output) of the injector. I do not see any large O rings that came out with the injector.

The diagram in the Service Manual only shows a small O ring (see attached).
My other picture would be my guess where the large O ring would go.

Am I on the right track here?
Thanks,
GT
 

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Discussion Starter #5
O-ring is present, its that wide band around the mid section of the injector. What you see missing is the pintle cap. One reason being these may have been replaced at some point with non oem injectors.
I do not see an O ring around the mid section of the injector. Just at the bottom of the injector (output end). When I pulled the injectors, the only O ring I am seeing is the one at the bottom.

Thanks
 

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I recall that now, the fuel injection system was a Bosch. I have cleaned three of them so far and they all seem to work fine. I will do the other 3 today. Plus the cold start injector.

My question about the O rings is that I only see the small O rings after pulling the injectors (assuming the small O ring is the one at the bottom (output) of the injector. I do not see any large O rings that came out with the injector.

The diagram in the Service Manual only shows a small O ring (see attached).
My other picture would be my guess where the large O ring would go.

Am I on the right track here?
Thanks,
GT
You're on the right track, I'm sure that large O ring is more plastic than rubber at this point. Like I said before, the pintle is different than the oem in 75 ones are. I 'm sure its fine.
 

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Discussion Starter #7
OK, what might the pintle be, I am not familiar with that term.
I guess what I am trying to figure out is do I need to order both small and large O rings.

Thanks
GT
 

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The smaller ones fit into the manifold and the Pintel or end cap goes in here. The larger one goes around the middle for a snug fit into the plastic holder.
 

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Discussion Starter #10
Thank you Palladin. That is what made sense to me. However I am trying to get them together now and they will not go together without a lot more force than I am trying now. I have attached a photo of how I am putting them together with the O rings. When I took these apart, there was no large O ring in the middle. But I am trying to put them in as I am putting this back together. I cannot get the silver mounting piece and the O ring on together. The O ring will go on the injector by itself but I can't get the silver mounting piece on over it. If I try to put the O ring in the mounting piece, it fits just fine but then I can not get that on to the injector - again without using a lot more force than I have tried so far. And I have worked at it pretty hard.
Anyone have any thoughts on this?
Thanks,
GT
 

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There is a large O-ring. It's right under the steel plate that the two screws go through. It looks like its so hard and fossilized on your injectors after all these years (typical) that it looks like part of the injector. But it does come off (and will allow the plate to come off, too. And yes, replace the O-rings with new ones.
Just guessing, but I think from the steel-band hose clamps that those injectors are original Bosch units. Injectors that have been replaced usually have regular screw-to-tighten hose clamps. (If you do replace the hoses, be sure to use FI-only hose, as well as FI-specific hose clamps - regular clamps won't get tight enough to work, at least for very long.)

As far as cleaning, how are you doing that? Normally it is not something the home mechanic can do safely or effectively, since the injector has to be both pressurized and electrically triggered. And since they operate at something like 3 volts (what the dropping resistors are for), ticking them off at 12 more than a few times could damage them internally - not to mention ignite whatever cleaning fluid you're using.

The preferred method - okay, MY preferred method - is to send them out and have them ultrasonically cleaned. These services are all over the internet and maybe still even be on eBay. For about $15-$25 per injector, you will not only get them cleaned properly, but their spray patterns analyzed and compared to one another. Well worth the $$$ and few days it takes to send and get them back, IMHO. I've done it several times on several different cars (not just Zs) and have been very pleased with the results.
 

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Discussion Starter #12
Wow, thank you 6shutr, yes, the large O ring appeared to be part of the injector and I had not tried to remove it. But yes, they do come off with minimal effort.

Yes, I think these are original Bosch injectors and I had to use a Dremel to cut the steel-band off of them. And yes, I am using FI hose and clamps on the injectors and back to the fuel rail.

As far as cleaning them, I am using a 3 volt battery set up with a neatly rigged tire valve stem (I got this from a utube video - (
) and shooting compressed carburetor cleaner through the injector when the electrical is applied. It seems to have worked great. All my injectors are firing very consistently and a good hard spray. I might be concerned about your comment on ticking them off 12 or more times could damage them internally. I probably hit that level on some of them, but they all are functioning the same before I put them back on the fuel rail. I thought about sending them out but this seemed to be a good method.

One concern I do have is that my cold start fuel injector does not seem to be working at all. My car was running rough for the first 15 minutes or so and then would smooth out. Not sure if that could have something to do with it.

Thanks again for your input!
GT
 

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Mr.GR75Z:

Relax; Mr.6shutr's caution was about using 12v to trigger them, which is correct. But you figured it out before hand, just fine. Me, I overcompensated by using 1.5v to trigger, but it worked fine also.

For a guy "new" to this, you had a good handle on the cleaning process. I used WD-40 and carb cleaner propelled by compressed air too, The only other step I used was to do an open-valve backflush or two to clear the internal screen.

So like so many refurbishments, you've learned that there is little that a determined fellow cannot do himself.

My only question is: what "steel band" did you have to cut off from where?

Congratulatons on Mission Accomplished

Cold Start valve: I doubt that this was the root of the 15min. of rough running, as the valve only operates on the start; after that, the mapping of the injectors takes over enrichment.

I assume you tried light voltage triggering with that too. You should be able to hear that puppy click as well. If you do, try soaking it overnite a couple times.
 

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GT75Z - Ha ha! What a neat system for injector cleaning! It's been a few years since I did it last, but whoever came up with that YouTube method was really creative. And looks like it would be very efficient and effective. I will certainly give it a try next time I need to.
 

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Discussion Starter #15
6shutr – Yes, the rig worked very well. If anyone decides to try it, remember to take the tire valve stem core out. Otherwise nothing will get through.

And Ensys - Here is a photo pointing out the metal bands I had to cut away from the injector.

GT75Z
 

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