Injector Replacement or Clean

[Orthocad]

I have a 1990 Comanche with a 4.0 engine. I’m considering either cleaning the injectors or replacing them. Any suggestions? If I should replace them, what do you recommend? This is a stock truck, so nothing fancy is needed.
 

Thanks,

Scott 

[Pete M]

junkyard injectors from whatever gives us the proper 4-hole variety.    mustang?  volvo?  I forget the specifics, but I'll be doing this exact thing in a couple weeks to the 88 I'm working on (as one of the factory units has split and is now spewing gas in the wrong direction.  it's a lovely spray pattern, but I prefer my gas to stay inside the engine.   )

[Orthocad]

3 minutes ago, Pete M said:

junkyard injectors from whatever gives us the proper 4-hole variety.    mustang?  volvo?  I forget the specifics, but I'll be doing this exact thing in a couple weeks to the 88 I'm working on (as one of the factory units has split and is now spewing gas in the wrong direction.  it's a lovely spray pattern, but I prefer my gas to stay inside the engine.   )

Yikes!! I’m just taking my time going through the engine right now. It’s running a little rough and seems to crank over several times before it starts. I plan on giving it a tuneup and checking the fuel injectors. I also want to check the timing chain and gears. I had a CJ that ran rough, and when I changed the timing gears and chain, it ran as smooth as could be. Checking the timing on it will tell me if the gears are worn. 

[Pete M]

ancient parts are ancient.    I'm just glad that I caught it now.  if she was driving it, this was a fire for sure. 

[eaglescout526]

With Renix, there’s a priming sequence of the fuel rail. If you click the ignition to run, the fuel pump will run for two seconds to fill the line and pressurize the rail and then you start the engine. That should help with your long or multiple cranking. 

[watchamakalit]

Have you done any of cruisers tips? 

https://cruiser54.com/

 

Many of them are designed to address the issues your concerned with. Not saying that will fix things. Just hate to see someone change parts that aren't bad.

[eaglescout526]

10 minutes ago, watchamakalit said:

Just hate to see someone change parts that aren't bad.

I’d hardly say going from a single stream injector to a 4 hole with better atomization a bad thing. 

[watchamakalit]

2 minutes ago, eaglescout526 said:

I’d hardly say going from a single stream injector to a 4 hole with better atomization a bad thing. 

Maybe I explained that wrong. I didn't want to see someone changing parts to sole a specific problem if that part isn't the cause.  ie: changing a tail light bulb to stop the brakes from grinding.

[watchamakalit]

I'm definitely not opposed to upgrades. 

[Orthocad]

1 hour ago, watchamakalit said:

Have you done any of cruisers tips? 

https://cruiser54.com/

 

Many of them are designed to address the issues your concerned with. Not saying that will fix things. Just hate to see someone change parts that aren't bad.

This good stuff!! Thanks for the information 😊

[pizzaman09]

The Volvo 746 injectors are the recommendation and what I went with.  Cruiser has a good write-up:

https://cruiser54.com/?p=438

 

I went with cheap eBay knock offs of the 746 injectors and couldn't be happier.  I have much smoother idle and a bit better torque over all.  Changing the injectors didn't help the longish cranking I have before firing, but it doesn't bother me and has never not started.  

[cruiser54]

NOTHING will eliminate the longish cranking of a Renix Jeep. 

There's a guy on Cherokee Forum that rebuilds the later injectors to use in our Renix Jeeps. I've used multiple sets with excellent results.

They even come with a flowsheet!!

 

 

trevor.skankfootracing@gmail.com

[watchamakalit]

7 hours ago, cruiser54 said:

NOTHING will eliminate the longish cranking of a Renix Jeep. 

 

 

 

 

Thats a relative statement.  At some point during the execution of your tips on my truck my crank to start time reduced by at least half.  I understand the renix will always crank longer than other FI systems, but that is not to say the crank to start time can't be improved.

[cruiser54]

Improved, but not eliminated. 

[Manche757]

6 hours ago, cruiser54 said:

Improved, but not eliminated. 

In seconds, how long are you talking about as optimal/expected?  I am not sure that I have a problem.

[watchamakalit]

7 hours ago, cruiser54 said:

Improved, but not eliminated. 

<---caught on a technicality

 

 

[cruiser54]

Sorta. But you make a great point about what the Tips help improve. 

[cruiser54]

1 hour ago, Manche757 said:

In seconds, how long are you talking about as optimal/expected?  I am not sure that I have a problem.

5ish. 

[speeding_infraction]

6 hours ago, cruiser54 said:

5ish. 

That makes me feel better. I thought there was something wrong with my truck. 

 

On 12/28/2023 at 4:13 AM, cruiser54 said:

NOTHING will eliminate the longish cranking of a Renix Jeep. 

There's a guy on Cherokee Forum that rebuilds the later injectors to use in our Renix Jeeps. I've used multiple sets with excellent results.

They even come with a flowsheet!!

 

 

trevor.skankfootracing@gmail.com

^^^these are the ones you want. Guaranteed to work. eBay knockoffs not so much. Got my knockoffs from Amazon and made my truck run way too rich, and and a terrible idle. Dropped my milage 3 mpg!

On 12/27/2023 at 5:45 PM, pizzaman09 said:

The Volvo 746 injectors are the recommendation and what I went with.  Cruiser has a good write-up:

https://cruiser54.com/?p=438

 

I went with cheap eBay knock offs of the 746 injectors and couldn't be happier.  I have much smoother idle and a bit better torque over all.  Changing the injectors didn't help the longish cranking I have before firing, but it doesn't bother me and has never not started.