HELP 89 Comanche 4.0 Constant Miss

[Coastal NC Jeeper]

Hello All

i have a puzzling issue with my newly acquired 89 Comanche 4.0

The truck has been sitting indoors for about 2 years prior to my obtaining it.

It ran great after draining a small amount of fuel out of the tank

 

I replaced a leaky valve cover gasket last night. (I was sober) 

After putting it back together, I started it up and now it has a constant miss at all speeds.

Tonight I replaced Plugs, Wires, Cap & Rotor, Checked all vacuum lines, checked connections on Fuel injection.

Still have the miss. 
Can anyone suggest anything else?

I have not replaced the fuel filter but have one and will replace it tomorrow.

I’m not new to Jeeps, but this is my first Renix. Thanks in advance 

 

[rokinn]

Two years is a very long time for gas to sit.  Given the symptoms I would guess it has fouled an injector or two.  I suggest draining the tank and putting fresh in along with a good injector cleaner and see if it clears up.  I wouldn't necessarily fill the tank this time, 10 gallons or so will allow for a more concentrated injector cleaner mix.  BG 44K is a very good one.

[Coastal NC Jeeper]

Thanks for your input! Drained the tank completely today and just ordered 2 B44K's Hopefully it will take care of the issue! 

[JMO413]

On any newly acquired Renix model cruisers tips are a must.

 

http://cruiser54.com/

 

Steps 1-5 are a must and the rest are just a good idea to work through.

[rokinn]

Changing out the fuel filter is a good idea also.

[Coastal NC Jeeper]

Update: 5 July 2021

 

Completed items 1-5 on the “Problem List” last night.

Drained entire fuel tank

Blew fuel lines out with low pressure 

Changed fuel filter

Reconnected everything 

Added 1/2 quart Lucas Fuel system cleaner and 1/2 tank of Premium.

Drove 50+ miles at highway speed

(Started and Stopped, etc)

Parked for several hours 

Drove 20+ miles

Came home in time for dinner Lol

 

At first the truck ran like crap, shuttering, missing, cut off.

As I continued at Highway speeds the truck began to run better and better.

 

By the time I finished up around 6PM, it was idling without a miss, still had a hiccup every now and then.

 

My plan is to run the reminder of the fuel and additive out and wait until the “Good Stuff” arrives on Wednesday 

 

Again, I can’t thank the forum for the great input! I’ll be in touch David 

[Ctwilson1]

Also worth giving the vacuum lines a good check or just relaxing them altogether. NAPA has the front and rear vacuum harness’s for less than $50 total. You never know if the rubber in those o-rings has rotted or a line has a nice little pinhole 

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

RENIX VACUUM HARNESSES

NOVEMBER 17, 2015 SALAD 25 COMMENTS

 

The vacuum harness that attaches to the front of the valve cover and includes the grommet/fitting, and is called the front harness, is Napa part number BK 715-1367 or is a Dorman 46003.

The vacuum harness that is closest to the air cleaner, EGR etc, and is called the rear harness, is Napa part number BK 715-1366 or is a Dorman 46004.

The tube from the rear of the valve cover to the intake manifold is part number BK 715-1365 or Dorman 46005 and comes with the valve cover grommet.

The Throttle Body to MAP hose is no longer available. Click HERE to access a fix for that.