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#1 09-14-2015 10:40:59

sucram
Rookie
Registered: 02-20-2010
Posts: 99

Tank Pump

I was just curious, is there a fuel pump in the gas tank on older Cherokees? I cannot find a fuse for one in the fuse panel, so it makes me a tad bit curious

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09-14-2015 10:40:59

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Re: Tank Pump

#2 09-14-2015 10:54:20

reblam
Enthusiast
Registered: 10-05-2008
Posts: 106

Re: Tank Pump

It's a relay fed by one of the large fuses in 91 up, maybe fed by a fusible link in Renix?
Either way it's fused and has a relay.
You'll find it under the hood, not in the interior fuse panel.

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#3 09-14-2015 10:58:56

michael
Helper
Registered: 02-03-2009
Posts: 31

Re: Tank Pump

The very early XJ's with the 2.8 and 2.5 had a mechanical fuel pump mounted on the engine not in the tank.

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#4 09-14-2015 11:03:20

sucram
Rookie
Registered: 02-20-2010
Posts: 99

Re: Tank Pump

Not a big problem, as the Injection Pump on the diesel can suck the fuel from the tank to the pump with ease

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09-14-2015 11:03:20

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Re: Tank Pump

#5 09-14-2015 11:57:54

reblam
Enthusiast
Registered: 10-05-2008
Posts: 106

Re: Tank Pump

I've read some interesting points on diesel swaps, one seems to point to using a "lift" pump back at the tank if you plan on running anything other than diesel in your diesel.
The theory is that it helps the injector pump by pressurizing the the fuel as it is sometimes thicker than actual diesel.

Although, there is the fact I know just enough about this to be dangerous and or completely wrong...

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#6 09-16-2015 10:03:21

sucram
Rookie
Registered: 02-20-2010
Posts: 99

Re: Tank Pump

When I ran Veggie Oil in my 1989 VW Jetta 1.6l Diesel, the tank had no pump, all the feed was provided by the IP, and I had no problems. The main reason I wanted to see if there was a tank pump was because I am cataloging wiring for the swap and a tank pump may have helped the injection pump cope with the turbo

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#7 09-16-2015 14:45:57

reblam
Enthusiast
Registered: 10-05-2008
Posts: 106

Re: Tank Pump

I've read that it does work fine to not use a lift pump, but guys that have had problems with colder climates seem to theorize that the lift pump makes a difference.
I still have not been up to my dad's to ask about whether they still have a diesel manual at the shop.
Shame I didn't keep the handouts I got when I took the training, I'm pretty sure I had all the info when I came back, but I know I gave it to the shop manager there at the time.
I was just doing oil changes and such looking for a better job and the only reason they sent me to the training was because they didn't want to send one of their "real" mechanics, notice I said mechanics as that is mostly what they were there. If it was a technical problem they would bring in a new car and swap parts till they found the problem!

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#8 09-16-2015 14:50:10

Jose
Helper
Registered: 04-13-2009
Posts: 28

Re: Tank Pump

My 98 2.5 Diesel has a Tank Pump, I dont know if the 2.1 Renault had a Tank Pump :(

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#9 09-16-2015 14:57:12

breabsrip
Helper
Registered: 02-13-2009
Posts: 35

Re: Tank Pump

while it probably wouldn't ever *hurt* to use a lift pump, i'd take exception to the part of the statement below where you say "*anything* other than diesel"; BioDiesel isn't typically any thicker than regular #2, or possibly even #1 Diesel fuel.
of course, if you're running Veggie Oil (Waste or Virgin), all bets are off.
WVO and SVO are typically much thicker than Diesel (or BioD).
getting them down to the same viscosity as Diesel (or BioD) usually requires heat.
of course, some people get away without heat to thin the fuel (at least for a while), and the sturdy inline-style injection pumps like what is found in our old Mercedes are much more tolerant of varying viscosities, but the higher viscosity fuels will eventually lead to trouble with either the injection pump, the injectors themselves, or even more serious issues resulting from the uneven spray pattern and droplets caused of unthinned fuel in the combustion chamber.

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