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Can anybody tell me what the difference is in 1988 4.0 injectors and 1996 4.0 injectors??? I'm thinkin there's a slight difference in flow rates. If so, how much???

 

I have an injector on my 88 4.0 thats leaking. I have a full set of injectors out of a 1996 ZJ sittin in tha tool box. What would be tha "pros" or "cons" in putting those 96 ZJ injectors in my 88 MJ?

 

Pending the answer from above, I was thinkin about taking an injector out of my 89 XJ to replace tha one thats leaking in my 88 MJ. Then temporarily replace tha one I took out of the XJ with one of the ZJ's so the XJ will still run good enough to be moved as needed.

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Thanks for the info. It answered my question. NO!!! The 96 injectors won't work in my 88. :(

 

Reckon I better git back top work since I now have two injector rails to R&R. I've already pulled all the injectors out of my truck once thinking I had an o-ring leak. Replaced all of the o-rings only to find out it's the injector itself thats leaking. :wall:

 

Thanks again.

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Those 96 ZJ injectors aughta work just fine after all.

 

"The injector flow rate varies as the square root of the pressure drop across the injector. The stock '91-'95 4.0 injectors are rated at 22lb/hr @ 43psi fuel pressure, so at 39psi they flow ( sq. rt.(39/43) x 22.0 = 21.0 )."

 

In my case, I have 10 lbs less fuel pressure than what they say a 96 is supposed to have. (1996-1999 / 49psi / 23.2lb/hr) (1987-1990 / 39psi / 18.6lb/hr)

 

So based on the formula above; If 4lbs less fuel pressure only gives you a 1lb/hr loss of flow, then a 10lb loss in pressure should only give you a 2.5lb/hr loss of flow. By that formula based on having 39lb of fuel pressure those 23.2lb/hr injectors should give me a 20.8 lb/hr flow rate. Thats an increase of only 2.2lb/hr of flow rate over the stock 18.6lb/hr rate. No problem. It aughta run fine. Perhaps a little better.

 

.

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Too much thinking in that post. I think i'm getting a headache from reading all the thinking he typed.
YOU??? What about me??? I havent had a headache like this since I was trying to figure out what frickin tires to buy. :wall: LOL!!!
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