Fuel Pump

[fltardrd]

I have an 88 Comanche and the thing won't start. I have noticed that the fuel pump isn't clicking when I turn the key on. I unhooked the fuel line from the fuel rail and turned the key on... no fuel was pumping out I'm thinking that the fuel pump died. if so do you have to drop the tank to get to it? any advise would be greatly appreciated.

[KYMJ]

No you don't have to drop the tank.

[Rokhound]

check that dum peice on the fire wall. Whats is it called :nuts: o that white piece jump the wires togther and see what happens becouse my would start and run and die. You might want to try this first. Just to make sure.

 

 

found what i was looking for check here

 

http://www.comancheclub.com/forums/view ... highlight=

[JeeperjohnfromPA]

ALSO check the wire harness inside the cab, right down where the parking break pedal is.

The wires for fuel pump run through there.

 

It is a Fairly common problem to have a short or bad connection in this area.

 

Also check the wires at the gastank itself, could very well be that one of them is bad or loose.

 

Good luck

[comanche-man22]

also if it is the fuel pump...you are gunna have to replace it. the bad part about that is when it is all said and done you will have to put it back in the tank...this is where it gets tricky. you have to pin the little circle door down with something long like a really long rachet wrench extension up against the frame rail and then you have to work the lock ring in and you have to try to get all 3 of the hooks in... :nuts: it really confusing thats why my truck sat for a year.... :cry:

[Eagle]

Fuel pumps don't click -- they whirr. First thing to check is if you're getting voltage to the fuel pump with the ignition on. (It won't be 12 volts because of the ballast resistor, it'll be about 9 volts.) Just unplug the connector in the wiring harness about 15" out from the pump. If there's no current at the pump, check the fuel pump relay and the ballast resistor.

 

Don't dive into replacing the pump until you know that it's the problem.

[partsmj]

Did you try switching the relays?

[juan]

Well - I just got done helping CW change his pump on his Mj - was a very easy job, took all but an hour and that included a beer brake. Everything came out nice and easy, it did help that CW sprayed everything with penetrating oil for a few days but overal was an easy project. CW will post pics as soon as he gets a chance.

[CWLONGSHOT]

Thanks for the intro Juan!!!

 

Yup, I have been experiencing some problems for the past couple weeks. In speaking with some friends we narrowed it down to three different possibilities.

 

1) The "plug" for the CPS. it shouldnt be there, factory requested all dealers remove plug and solder wires.

 

2) The coil/ignition module. mine had some pretty bad cracks in the epoxy. I swapped it for another I had. I THOUGHT this fixed it...but a couple days ago the porblem returned.

 

3) The fuel pump. Now I KNEW I had somewhat of a problem here as my Fuel rail will not hold pressure for more than a couple hours. Recently it just wouldnt start after sitting overnight. then Wednesday, it stalled when pulling out into traffic and was VERY hard to get started. the next AM, it wouldnt start again. SO, i decided to change out the pump. I figured, it cannot hurt and it will fix my pressure problems anyhow.

 

 

Here is the OLD assembly:

 

 

It came out with realitive ease. Two of the tabs bent over but where easily bent back.

 

There are two different pumps that COULD have been in my 1989 comanche.

 

 

I removed the old pump form its cradle and re-installed the new pump and its fittings:

 

 

Then Juan put it back in and changed the filter for me:

 

 

Lastly, here is a video clip of the install and one of the jeep running after the install. enjoy.

 

 

 

CW

[JeeperjohnfromPA]

So has the new pump fixed the probelms?

[SomeNew Name]

CW you notice in your post with the pictures the 6th picture down from the top and under where your left hand is covering, you know those two solid lines that come out if the disc for the tank and that the rubber hoses connect too.. well I managed to snap the return one off...

 

Now how would I go about fixing that jazz?

[CWLONGSHOT]

I would just try to get a replacement.

 

If none where available you could fashion a new one with new tube and a Propane (Only use map) gas torch. Its only soldered together.

 

Maybe if you would post up a pic, so I could see how bad it is, I would have other suggestions.

 

CW

[SomeNew Name]

well i don't think I can get a pic for at least another coupleof days my girl has my camera and she's down south right now visiting friends and family..

 

but I can explain it pretty good

 

ok I'll refer to that circular gas cover as the "disc"

 

the return line is not completely broken off but it is cracked about 3/4 of the way around the diameter of the line on the exterior part of the disc.

 

this crack started 1/8in away and parellel to the disc..

 

it's still hanging there.. and sometimes fuel just pisses out and sometimes it doesn't... I guess that's when too much is sent to the rail?

 

I'll try to get a picture for you in the next couple of days when she gets back.

[CWLONGSHOT]

Could you apply something like a JB weld (Be sure its fuel proof) and build up the area that's cracked. After-all, this doesn't move once installed and if you re-enforce the area so as nothing can move at all, you should not have to worry about vibrations working loose the repair.

 

Just a thought...

 

CW

[Wolfgang]

Where is the fuel pump relay located? :???: I am not getting voltage to my fuel pump. Does any one have a wire schematic for the fuel pump? ;)