Towed for the first time with the KK and gave it a good test

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Liaztraht

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It will make a huge difference
Both of my 03 and 04 , 03 on 31s and 04 on 32s are running 4.10s
and have full diffs with 4.10s ready for the 05 when it goes higher
Have also done quite a number of others for them
KJs are lucky in that we can use 4 cylinder gasser 4.10 diffs
But the KKs can go even lower than 4.10s so a trade off in a way
Yeah, I believe it was the same 4.10s as the JK right?

It's still got enough juice to chirp the tires on dry pavement, but more oomf would be nice.
 

lfhoward

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Yeah, I believe it was the same 4.10s as the JK right?

It's still got enough juice to chirp the tires on dry pavement, but more oomf would be nice.
Yes, we run the same front gears as a Dana 30 JK. Rears are Chrysler 8.25 on the KK & KJ, 29 spline IIRC.

Would love to regear to 4.10. Have 245/75R16 tires also. Could go lower but 4.10 will bring it right in line with stock gear ratio with this tire size. If running a 32 inch tire, 4.56 is the way to go.
 

Liaztraht

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I'll be saving for a while. That's one of the few things I can't do in my driveway.

I do need to swap the fuel pump out, mine has developed a whine and occasional starting issue. Pressure is fine on the injector side of things, but fuel does sometimes leak back when off. So I'm changing it out. Doing brakes at the same time. My Saturday is too booked to take it out on a trail :(
 

lfhoward

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Hijacking your thread for a second:

The fuel pump thing: does your KK struggle to start when hot? If I turn my Jeep off, do a 5 minute errand, and then come back and try to start, it cranks and cranks but struggles and can’t start. If I wait another 5 and it cools off it can start fine. I suspect my fuel pump letting gas back flow when turned off, leading to a vapor lock situation with the heat. I have an 08 with 175K miles, original fuel pump.
 

Liaztraht

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Hijacking your thread for a second:

The fuel pump thing: does your KK struggle to start when hot? If I turn my Jeep off, do a 5 minute errand, and then come back and try to start, it cranks and cranks but struggles and can’t start. If I wait another 5 and it cools off it can start fine. I suspect my fuel pump letting gas back flow when turned off, leading to a vapor lock situation with the heat. I have an 08 with 175K miles, original fuel pump.
For me it's only happened a couple times on a cold start. Just cranks till it hits the auto shut off. That's on a hot day though.

For the wife it's mostly the same as you.

Mine is a 2011 with 103k on it. Assuming stock fuel pump.
 

lfhoward

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Interesting. Just seeing if there is any evidence for the fuel pump theory. The Jeep doesn’t do it regularly enough to be able to get a real diagnosis.
 

Liaztraht

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Interesting. Just seeing if there is any evidence for the fuel pump theory. The Jeep doesn’t do it regularly enough to be able to get a real diagnosis.
The new whine is enough for me. Perhaps I will get lucky and solve the issue.
 

tommudd

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Wonder what brand or who they got the fuel pumps from for the KKs
I've heard of issues before but never on KJs
 

sota

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*snicker*
16mpg when towing the car trailer, loaded.
 

Liaztraht

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Wonder what brand or who they got the fuel pumps from for the KKs
I've heard of issues before but never on KJs
Dunno what they OEM'd but I dropped a Delphi pump in mine on Saturday. Don't know if it solved the occasional starting issue, but there is a noticeable difference in available power at freeway speeds.

I enlisted my dad to help drop the tank, and on the way to his house I bogged down while accelerating from 60 to pass a wide load in front of me. Floored the gas just to watch the RPM creep backwards!

After the swap I was powering to 90 without realizing it as I'm used to it driving like a pig.

Probably would have had a better time towing as well if I was getting proper fuel pressure.

Inside of the tank was pristine. The old pump may have just been garbage.
 

Silvertwinkie

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Greetings from the UK. I don't know if the KK is available with a diesel engine over there, but I would highly recommend one for towing. The 2.8td is a lovely engine with lots of torque and only 10bhp lower than the 3.7. I pull Airstreams over here, usually my 17ft Caravel that weighs in at 2500lbs. However, I did own a 25ft Trade Wind that was 4500lbs and with a Class 3 hitch fitted and a weight distribution kit on it pulled just fine. I could easily pull at 70mph and uphill at 60 if I needed to. Btw, I did previously have a 3.7 that pulled my little Caravel down the Mulsanne straight at Le Mans at 80mph. Luckily, I had it converted to lpg so didn't need a Gold Card to pay for the fuel! lol!
 

LibertyTC

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Interesting. Just seeing if there is any evidence for the fuel pump theory. The Jeep doesn’t do it regularly enough to be able to get a real diagnosis.
When it's not starting, ever tried removing the gas cap to allow air in? Be interested to know if that helps.
 

sota

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I haven't looked, but are our fuel systems returnless? if so depending on where the pressure regulator is (at the rail, or at the pump) if it starts to go bad, it can let pressure out of the line. when you get the engine nice and hot, it can then vaporize the fuel in the rail, making it harder/longer for the system to re-prime on a hot restart.
 

Liaztraht

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I haven't looked, but are our fuel systems returnless? if so depending on where the pressure regulator is (at the rail, or at the pump) if it starts to go bad, it can let pressure out of the line. when you get the engine nice and hot, it can then vaporize the fuel in the rail, making it harder/longer for the system to re-prime on a hot restart.
Pretty sure it's in the pump.
 

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