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L28 Fuel Injector Replacement


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#1 6spd_monte

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Posted 28 September 2017 - 01:04 PM

First project time on my new-to-me 810!

 

My uncle had described to me that his 810 was hard to start when cold, and wouldn't idle on it's own until it was up to temperature and even then the idle quality was poor.  It had been diagnosed as a problem with the injectors and before he died he had purchased a new set.  When I went to move the car to my house it ran just as poorly as he had said.

 

So, for my first project I figured I'd get those injectors installed for him!  In my introductory post I mentioned that one of the items on my to-do list for the car was to clean up the engine bay, and while the fuel rail is out this is a good time to start.

 

Getting started, labeled the injector leads to make sure I don't mix them up.

R6urbsf.jpg

 

Harness out of the way.

SN3M2UE.jpg

 

Rail out.

GsI7BDS.jpg

 

And on the bench.

nQ3l8bo.jpg

 

Disassembled and cleaning off the oxidation.

2ZTjvNh.jpg

 

I'll post more pics as it goes back together.

 


-James

1979 810 Coupe


#2 6spd_monte

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Posted 03 October 2017 - 10:16 PM

So, here's the fuel rail all cleaned up.  I've decided I want it to stay looking nice so I'm sending it out to get plated.  Silver cadmium, nickel or zinc, I'm not sure yet.  I think that the original finish was that iridescent gold cadmium, but I like silver better.

 

P2xMhIb.jpg

 

Also, I've continued my mission to clean up the rest of the engine bay.  No pics yet because I want it to be a surprise! 

While I was going over everything with a rag and wiping the dust & dirt off, I noticed that the air hose running from the intake elbow up to the cold start air valve was really loose. 

Further inspection revealed this:

 

VXPCaDL.jpg

 

I'm pretty sure that a new set of injectors isn't going to make it run any better with this massive vacuum leak.  I'm going to fix this and put it back together with the old injectors, I'll bet that it runs just fine.

 

Stay tuned...


-James

1979 810 Coupe


#3 Crashtd420

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Posted 04 October 2017 - 01:54 AM

Your probably right with that air leak... just wondering if you can bench test the injectors before you reinstall....
Make sure they all spray the same and work
Not sure if possible or how but might be worth looking into.....

#4 datzenmike

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Posted 04 October 2017 - 05:40 AM

Not so much a vacuum leak as unaccounted for air getting in past the MAF sensor ahead of the throttle body.


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#5 6spd_monte

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Posted 04 October 2017 - 07:31 AM

Your probably right with that air leak... just wondering if you can bench test the injectors before you reinstall....
Make sure they all spray the same and work
Not sure if possible or how but might be worth looking into.....

 

That is a good idea. I'm thinking of how to do it, I would need to have everything connected to it. Extending the fuel and vacuum lines would be easy but extending the wiring would be harder. I'd want have it far enough away that it doesn't spray fuel all over the engine. I don't think it'll reach and I don't want to molest the wiring harness.  I think there's a place I can send them to get inspected, I'll look into that. 

 

Not so much a vacuum leak as unaccounted for air getting in past the MAF sensor ahead of the throttle body.

 

I suppose you're right, Mike. Not too much vacuum on the front side of the throttle. I think the industry term for this would be an "un-metered air leak". 


-James

1979 810 Coupe


#6 6spd_monte

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Posted 04 November 2017 - 09:55 PM

Ok guys it's all back together and I must say, it runs like a champ!

@Crashtd420 I was able to send the injectors out to a place called Witch Hunter Performance (http://witchhunter.com/).  They came back with a report card showing before and after testing, turns out they were in pretty good shape to begin with but there was some room for improvement.

 

I was unsuccessful in locating a new intake duct, I guess they've been NLA for quite some time.  I looked into building one out of tubing and silicone couplers but the available silicone elbows don't have a tight enough radius to work in the space available.  I thought about fabricating one out of tubing using the "pie cut" method to make my own tight radius bends, but I decided that much fabrication is over my head right now and the time it would take me to learn it would mean the 810 would be out of action for too long.

 

So, here's what I did; I bought this thing:

http://www.siliconei...ger/-p-500.html

It's for adding a vacuum port, gauge fitting, blow off valve, etc to your custom silicone intake plumbing. 

Here's what I did with it:

 

I cut off the damaged port on the original duct, and enlarged the hole in the tube.

L7JI6h2.jpg

 

I didn't use the thick rubber gasket that came in the kit because it was kind of stiff and I felt it would have required a lot of clamping force to seal.  I cut some thinner, softer gaskets from an old bicycle tube and used one on the inside and one on the outside of the fitting.  You can see both here.

tkfTXBp.jpg

 

Then I bought a 1/2 NPT 90 degree fitting.  I really needed one that was a 5/8 hose barb on the other side, but nobody in town had one and I was too impatient to order one. 

NNd37pK.jpg

 

So, I made this rig so I could chuck it up in my cordless drill.

rIftTNd.jpg

 

Then I made it spin really fast and removed the threads with a coarse file.  At this point, I was really wishing I had a lathe...

oo9iGXv.jpg

 

So now it looks like this.

f67TFIN.jpg

 

Here's the assembled port system.

Outside

4hkqynD.jpg

 

And inside

RpTaHu8.jpg

 

And with the fitting installed

WBTAt1S.jpg

 

There were still some small cracks around the hole.  I remember reading this really good article http://hiperformance...m/Ljetronic.htm where the guy talked about sealing up cracked air ducts with a product called "Shoe Goo".  I know, I was skeptical too but with a lack of other options I decided to give it a try.  I think the stuff is basically rubber cement.  It seems to be sealing up fine for now, I'll obviously be keeping an eye on it.

 

Of course all the fuel hoses in the engine bay got replaced along with a new fuel filter.  When I activated the fuel pump to check for leaks before starting the engine I caught a pretty good leak out back at the fuel pump.  I'm sure is wasn't there before, and I know I didn't touch anything back there but whatever.  It ended up being just a couple of loose hose clamps.

 

And, I finally finished cleaning up the engine bay and I'm quite pleased with how it came out.

Before:

 

GrN3bfO.jpg

 

After

 

RO6Tqm2.jpg

 

So that's where she's at right now.  I'm happy and the car is happy. 

On to the next project....

 


-James

1979 810 Coupe


#7 john510

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Posted 05 November 2017 - 09:34 AM

Nice job on the intake hose repair.Nicer job cleaning up the engine bay.Looks good.



#8 Stoffregen Motorsports

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Posted 05 November 2017 - 09:39 AM

Looks great. I like your homemade lathe.



#9 Lockleaf

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Posted 06 November 2017 - 10:38 AM

Nicely done

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