1997 Fuel Pump Diagnostic

[Land Surveyor]

I think Ive read all of the info here but would love some opinions.

1997 4.0. I bought it used and it gets used 4 months per year at our hunting camp. Fresh tune up and no work to fuel system.
Im starting to get what I believe to be the fuel pump drain back problem. When it sits for more than 20 minutes or so it has to reprime with 3 or 4 or 7 on/off cycles. I loaded it on the trailer to bring it home to repair and realized that after I winched it up on the trailer it fired right up on the first turn after letting it prime up. When I went to unload the next day it was not wanting to prime. I can hear the pump running but after 7 cycles still no joy and the pump just continues to run. I push it off the trailer and BAM it fires up after priming for just a few seconds. So I experiment with jumping up and down on the back. Its crazy but when I do nothing, the pump runs forever and it won't prime. If I jump on the back a couple of times it primes in seconds and starts like new.

My thoughts was, sounds like a clogged fuel filter. Then I read that 1997 has no serviceable fuel filter as it is in the pump.

So, I guess I need to drop the tank and change the fuel pump? Or does this sound like something else?

I have not checked fuel pressure yet. I plan on doing that next.

Last stupid question... this is an off road Jeep. She will never see rhe road again and I am open to permanent modifications. Is it feasible to cut a hole in the floor to access the fuel pump to avoid having to drop the tank? Ive seen people do similar by cutting the firewall to access the heater core for replacement.

 

[MtPockets]

Dropping the tank is easy.
There are plastic screens on the pump that are likely getting clogged if it sits that much.

You can buy the screens at Autozone.
I'd also recomend using SeaFoam or StaBil in the gas before you park it for the season.

 

[Gilaguy23]

yes, a hole can be cut in the floor to access the pump. BUT.....and I cant recall on the TJ or YJ, but the ZJ I did the top of the tank was very close to the floor panel. Im glad I dropped the tank first to have a look and not worry about hitting the tank.

 

[macleanflood]

I'd almost live with the cycling issue.

Problem is modern gas.

I guarantee you'll be doing this again next year.

Startron is a good fuel stabilizer.

Rock Auto has Brute Power fuel pumps for like $60. Mine's two years old and I've beaten the living crap out of my fuel tank...two trips to the Rubicon, one to Moab and a 1600 mile road trip to Canada and back on the WABDR.

Genright makes a hatch.

If you replace most of the nuts and bolts with riv nuts...I used M8 on the skid and like M4 on the fuel neck...I can have the tank down on a floor jack in less than 10 minutes and not much more to reinstall.

Make sure your wiring and fuel line are secured well away from the track bar mount on the axle.

-Mac