The fuel pump on my Max passed through to Valhalla last month. My mechanic warned me that with all the rust around the area, he couldn't guarantee that dropping the gas tank to replace the pump wouldn't cause collateral damage to something. Sure enough, once I got the truck back, I started noticing a gas smell and that the engine needed to crank a while when starting before fuel reached the engine, and now that the streets have dried out a bit I was able to spot the gas leaking off the tank. The mechanic used a mirror to spot the leak near the top of the tank and warned me a replacement part would be difficult to come by. It is supposedly not something normal parts places deal with and he told me we'd have to find something off a parts vehicle from a winter/salt free region, as the equipment in that area of my truck was too rusty to fabricate anything onto it.

However, after getting home and checking in the sevice manual, I'm not sure what it is I'm looking for. He called it the "sending unit" and mentioned that it was seperate from the fuel pump. The manual has nothing by that name. (It also doesn't have the fuel pump itself labeled, so I'm wondering if the manual writers were sick of this section and decided to skip ahead to something cooler? <img src="/forums/images/graemlins/confused.gif" alt="" /> ) Anyway, I called the garage and talked to the office guy that helped with my repair. He was convinced it was close to the fuel pump but couldn't pinpoint the part from my description of the diagram.

The parts that are listed: the 'packing', 'fuel pump assembly' (a disc with hoses/wires routed through, but with the 'packing' between it and what looks like the actual [unlabeled] pumping mechanism that drops into the tank), a 'fuel pump connector' on the assembly, and the 'main' and 'return' hose connections.

Any ideas which of these parts would be referred to as a 'sending unit' and/or where rust-free versions of them (or the whole gas tank assembly) could be acquired by someone in Milwaukee?

"sender" is a term for the variable resistor connected to the fuel gauge...usually.

what was the question again?

okay. It looks like the thing in a toilet tank - a float attached to an arm attached to the resistor,
It passes wiring out the top of tank with the pump power, so I guess the guy is saying the leak is there.

dont know about rust proof version

Ask your mechanic if the leak is on the fuel line part of sender assy, or if it is from around the donut(gasket sealing assy into tank). If it is fuel line part, a new sender/fuel pump assy should fix it, sometimes a rusty gas tank leaks around the donut, then you need a new gas tank. Try car-part.com for both.

Yeah, car-part.com and a southern junkyard. The fuel pump is mounted on the bottom of the fuel pickup tube, which comes thru the SAE flange as a steel line. Fuel return is thru the other pipe. The flange also mounts the fuel level sender, a float on an arm attached to a 'lectron thing, a variable resistor, than varies the current to the fuel gauge. The packing is the gasket that seals the SAE flange to the fuel tank. If the top of the tank is sound, get a JY sender/fuelpump complete off a junker. I'd replace the pump part with new while you are in there. Under a $100 for the pump, I'd guess. I've had good luck with Master brand aftermarket fuel pumps from AutoZone. Get a new fuel strainer for the bottom of the pickup tube, too.

While I had the tank dropped, I'd hit the whole thing with POR15 rust converter and a good coat of hefty paint. If you can see any internal rust in the tank, you can save it with a tank sloshing sealer. Some kind of rust converter/epoxy stuff that you mix and slosh around to coat the entire inside of the tank.

Have you done a Google on new fuel tank Mitsubishi truck?

Here's where I'm wondering about the shop manual - it shows the 'Fuel gauge unit' and 'Fuel guage unit connector' seperate from the whole pump assembly listed above, but neither has any of those dashed-line thingies to indicate where they go in relation to the tank. From where they are floating in the drawing, I'd guessed that the pump goes into the hole in the front of the top of the tank while the guage asmby goes in a separate hole near the back. Could you be thinking of another model or year?

I just had the whole pump/screen/filter replaced, which is what seems to have lead to the leak. The mechanic got the parts through his regular guy, which ended up costing $280 instead of the $180 I priced at partswarehouse.com, but I needed it done in a hurry and he said he would only warranty the parts from his guy. When the screen fell off and blocked the fuel flow on the first trip I took, he did fix it for free but I was stuck with the $200 tow bill.

I more or less trust the mechanic, but he has never been too enthusiastic about working on a high-milage rusting import. I like the truck and it's well suited to my needs, but I'm not sure if I can keep it rolling until I have a place with a garage so I can do the kind of work you're talking about. Do month-to-month storage spaces make good repair bays?

ebay has nothing - how trustworthy are the folks on car-parts.com? If they tell me something is rust-free, what keeps them accountable to their word?

Would it be Ok to scan a page from the shop manual and link to the image in a post here?

I've done it once or twice, but every time afterwards I saw a strange Fuso parked outside.

If the truck is similar to the Montero, the fuel pump and the gauge sender unit are both mounted towards the top/front of the tank. The sender unit mounts in a separate hole next to the fuel pump, and has a separate gasket. For comparison go here: sooper-sekret linky and look at the '92 Montero FSM for engine, chassis, body. Look at the drawings starting on page 13-97 and compare with what you've got. The drawings show a separate mounting for the sender unit on the driver's side of the fuel pump mounting location.

Does the truck have an access plate in the bed so you don't have to drop the fuel tank? If so, then replacing this yourself should be relatively easy.

Good luck! <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

If the tank is rusted out and a replacement is hard to find, can't a fuel cell be used instead? May be they are really expensive. Just a thought <img src="/forums/images/graemlins/cheers.gif" alt="" />