89 YJ with '02 4.0 questions - JeepForum.com

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post #1 of 21 Old 11-02-2013, 10:15 PM Thread Starter
bpeelen
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89 YJ with '02 4.0 questions

I have a 89 YJ with a 4.0 from a 92 Cherokee. I am told my jeep has the 15 gal fuel tank, so I am wondering if the guy PO changed the fuel pump when he went to the fuel injected motor. I have had little luck finding a fuel pump that is listed for the 4.0 equipped YJ and fits the 15 gal tank.

The reason I am wondering is because the jeep does not like to start very well when cold. I don't see an add-on in-line pump either, do I need to add one? What fuel pressure will this motor need to operate properly?

I have the Cherokee harness and computer under the hood cobbled into the original harness.

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post #2 of 21 Old 11-02-2013, 10:19 PM
Dake
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Do you have the plastic tank or metal. I don't think the metal one will use the tank pump.

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post #3 of 21 Old 11-02-2013, 10:39 PM
Michaelgoesrawr
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Jeep switched to the 20 gal poly tank when they added the 4.0 motor in wranglers. I'd venture to say you need one of those with a pump and it would be okay. MTS tanks should have what you need.

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post #4 of 21 Old 11-03-2013, 09:31 AM
JeepCrz
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89 F 150 6 cyl fuel pump. It is an E2000. You will need a filter (I used the 94 Cherokee filter) between it an the tank. It will put out 40psi. I have this mounted on the cross member in front of the fuel tank and have been running it for six years. I did have to replace the pump this year but they are only around $80. Much cheaper than a pump, tank, and skid plate that you would need to use an OEM style pump.

2010 Jeep Liberty > Stock < wife's
1989 Jeep Wrangler > 4.0 conversion, 4" lift, 33's
1985 Jeep CJ7 > AMC 360, 4" Lift, 35's, locked front and rear, winch, Onboard Air, ect..
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post #5 of 21 Old 11-03-2013, 01:25 PM Thread Starter
bpeelen
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Oops, read below, double posted somehow.

Last edited by bpeelen; 11-03-2013 at 01:28 PM. Reason: Double post
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post #6 of 21 Old 11-03-2013, 01:27 PM Thread Starter
bpeelen
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So this F 150 pump is an external electric pump? Sounds like a good option.

I need to drop the tank anyway and figure out why it reads empty at a 1/4 tank. That will give me a good chance to look at what is in there for a pump and how to rig up something new.

Did you leave the stock pump in the tank and just add the F 150 pump as an auxilary?
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post #7 of 21 Old 11-03-2013, 05:07 PM
Que89YJ
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The stock poly tank pump puts out more then enough pressure on its own. If you have a problem with cold starts look at your fault codes and if you think there is a pressure problem find out what your pressure is. Don't throw parts at an issue, troubleshoot.
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post #8 of 21 Old 11-03-2013, 05:13 PM
idskot
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Could be a partially clogged fuel filter, or a myriad of other things. The proper thing to do is diagnose. First see which tank you have... the first tanks used in the YJ were simple 15 gallon square tanks with a single strap holding them to the skid. They were made of metal, btu I believe there are a few out there that are poly. After '91 (when they switched to the 4.0L FI), they switched up the fuel tank to a technically 20 gallon poly tanks that look kinda like a trapezoid. ( /__\ ).

The early square tank has a round entry point on top of the tank, while the 20 gallon poly has a square one.

I'd say first step: figure out which tank you have.
Second step: find out your fuel pressure.
Third step: replace fuel filter and recheck fuel pressure.

Then go from there.
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post #9 of 21 Old 11-03-2013, 05:23 PM
JeepCrz
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My jeep didn't have an in tank pump when I did the conversion. I have an 89 Sahara with the 20 gal plastic tank. The f150 pump is inline. If you are dropping the tank you may want to just install it there with a factory one from a fuel injected YJ. If I recall the 4cyl and 6cyl YJs used the same pump with the same pressure but you would have to verify this with the part numbers.

The yj swap use to be well documented in cjoffroad.com but the site went away.

edit...
Looks like they are the same pump.

http://www.4wd.com/search.aspx?Actio...-c6ecefcc93cb#

2010 Jeep Liberty > Stock < wife's
1989 Jeep Wrangler > 4.0 conversion, 4" lift, 33's
1985 Jeep CJ7 > AMC 360, 4" Lift, 35's, locked front and rear, winch, Onboard Air, ect..
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post #10 of 21 Old 11-03-2013, 05:58 PM
idskot
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Quote:
Originally Posted by JeepCrz View Post
My jeep didn't have an in tank pump when I did the conversion. I have an 89 Sahara with the 20 gal plastic tank. The f150 pump is inline. If you are dropping the tank you may want to just install it there with a factory one from a fuel injected YJ. If I recall the 4cyl and 6cyl YJs used the same pump with the same pressure but you would have to verify this with the part numbers.

The yj swap use to be well documented in cjoffroad.com but the site went away.

edit...
Looks like they are the same pump.

http://www.4wd.com/search.aspx?Actio...-c6ecefcc93cb#
I know there's two different pumps for the 4.0L. One has screw on terminals, and one has a plug-in terminal. The screw on terminal one was more expensive, and the one I had in my '91 YJ. (It is also physically larger, so... there's that as well.)
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post #11 of 21 Old 07-03-2014, 03:47 PM Thread Starter
bpeelen
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I thought I would revisit this post. I have a plastic tank in my 89 YJ. Gauge reads 1/4 full when actually empty. I replaced cap, rotor and wires recently to fix other problems but I still don't know what I have for fuel pump in this Jeep. Not sure what PO did when swapped out 4.2 for the 4.0. Need to catch buddy one day and test fuel pressure at his shop. If my tank is plastic does that mean it is a 20 gallon? I have never managed to put more than 15-16 gallon in it so far.

I know my jeep is missing a sensor at the front of the engine, PO plumbed in under dash temp gauge's sensor into hole, I think the missing sensor detects manifold temp for computer. This may be my cold weather, hard start issue.

Anyone have any good suggestions for cleaning up my dual engine harnesses under the hood (old 4.2 harness and new 4.0 harness are both there with some wires shared)? I would like to clean this up if anyone can tell me where to get pins for the firewall connector. Also, is there any reason that I can't use all the factory 89 gauges to read this 4.0? Oil pressure gauge is constantly bouncing and PO added temp gauge. Are the 4.0 sensors different from 4.2? Can I modify to make factory gauges work? I am looking for advice.
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post #12 of 21 Old 07-03-2014, 04:38 PM
Que89YJ
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91 harness and all your gauges should work. Plastics tank is a 20 gallon and mpfi you must be using the mpfi pump. The sensors are the same.
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post #13 of 21 Old 07-03-2014, 04:52 PM Thread Starter
bpeelen
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91 under hood or under dash harness?
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post #14 of 21 Old 07-03-2014, 04:55 PM
Que89YJ
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91 engine harness. 92 will work very easy too with the least amount of work.
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post #15 of 21 Old 07-03-2014, 04:56 PM
Que89YJ
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I mean that specific for your 87/90
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