Delica Canada | Mitsubishi Van Club

Hello!

So I'm planning a wee trip on the weekend, thought I'd do some pro-active maintenance. Changed my air filter, felt pretty good about it. Today I decided to change the fuel filter. Got the NAPA one. Turns out this is a very unpleasant job (at least for me). It was hard to get the filter wrench around the filter and enough room to loosen it off. Managed it eventually (although not before wondering if I should really be fiddling around with this at all).

I unscrewed the small plug (pressure release valve?) which is a part of the plastic unit that screws into the bottom of the filter, unscrewed the plastic unit (and the diesel was all over the place by now), unscrewed the filter itself, and took it out. It was Japanese, and had probably been on the van a very very long time.

I put a bit of oil on the top of the filter to lubricate the seal, climbed underneath the van, and screwed the fuel filter in place. I then replaced the plastic unit with the new o-ring that came with the filter (the old o-ring looked a little flattened), and screwed the plastic plug back in. At this point I was feeling pretty good about things.

Then I tried to prime the fuel filter by pressing down on the pump (round piece of metal on top of the fuel filter assembly) repeatedly. All of a sudden, fuel started dripping out of the plug (pressure release valve?) that screws into the plastic unit which goes in the bottom of the filter. I was quite distressed by this.

Worried that the new seal hadn't seated itself properly, I undid the plastic unit on the end of the filter, and put the old o-ring back in, did everything up, tried to prime the filter again, and again there was the dripping from the valve.

If that thing is the pressure release valve, does it make sense that when you pressure up the fuel system it releases the diesel?

We tried starting the van and it was pretty touch and go. Had to keep the revs up or it would stall. When it stalled we primed the filter with the little pump, and started it up again. For a while I couldn't keep it idling unless the revs were high, if it dropped too much it would stall. Repeat the priming. Tried loosening the bolt below the pump, thought it was the air release (hoping to bleed the air from the system)? Didn't seem to do anything.

After a long bout of pumping/priming fired up the van and it seemed to run fine, even at low idle. Assumed that the air had worked itself out of the fuel lines. The dripping seemed to stop out of the bottom of the fuel filter.

Started driving (long way back home), and as I was slowing down before a red light the red indicator lights on the dash turned on and I realised that the engine had stopped. Started it up again with some difficulty. This happened several more times. When I could finally pull off the street for a moment, I tried priming the filter again (more pumping) and after that things went okay for a while, then one more stall. Had to keep putting it into neutral (with throttle lock holding the revs a little higher than normal) when I stopped to avoid the low idle and stall situation.

Now I'm back home, and there's still fuel dripping from the end of that plastic valve thing, and I'm getting quite worried. I don't know what I've done wrong but I wish I'd just left the old filter on there.

Did I tighten the filter too much? Should I go back to the new o-ring? Does anyone have any idea what I can do to make the fuel stop dripping out of there?

Any help would be much appreciated. Sorry about the long description. Thanks!

Did you fill the new filter with diesel before putting it back in? If not for sure you have air in your system and need to bleed it out. Crack the first injector and turn the engine over until bubbles stop forming around the injector and then tighten it up. You may need to repeat this to each injector. There are a few methods of bleeding the sytem this is just one of them.

Did you shut the drain cock properly? That plastic thing at the bottom of the fuel filter is a water drain (there is a float inside which will illuminate the 'acorn' symbol on the dash).

Best way to change these filters is to remove the hoses, unbolt the mounting from the engine bay wall, remove the drain, remove the filter, replace the filter, bolt it back to the engine bay wall, attach the hoses.

It's also very important when you use the plunger to prime the filter, that you first unscrew the actual bleeder bolt which is on top of the filter facing the front of the engine. About a 8 or 10mm bolt I think it was
Unscrew this bolt a few turns, don't actually remove it. Then use the plunger on the top. Keep pumping/priming until no more air bubbles come out. Once all the bubbles are out, on your last down stroke of the plunger, tighten up the bolt so no air gets back in.

Perhaps if you're not undoing this bolt first, you're forcing air/fuel out the water drain valve on the bottom??

I will try cracking the injectors to bleed the air out.

When I undid the bleeder bolt and pumped the plunger there were no air bubbles coming out where the bleeder bolt was, but there was fuel dripping from the water valve underneath the filter. Is that normal?

Thanks for the advice on how to change the filter properly mararmeisto, it certainly would have been valuable yesterday, and I'll have to try it again to make sure it's done right. Could be an important piece in the wiki.

I will take a look again tonight after I redo the filter, and see if I still have the dripping and stalling issues. Thanks for the info!

I tried cracking the injectors to bleed the air out of the fuel system, does anyone know of another way to do it?

i disagree that you need to crack the injectors to bleed out air. thats what the bleeder screw on the filter housing is for. i believe that in most cases its unnecessary to bleed at all, that the air will push through the return. ive done this a bunch...

i would remove the whole filter housing (like mararmeisto does) and disassemble and reassemble all the parts to make sure its right. the drian valve opens and closes, the "wings" at the base of the water drain nipple,and the whole plastic assembly screws in and out of the bottom of the filter...
good luck

I've taken the whole filter assembly off (disconnected fuel lines, disconnected the wires that run to the plastic plug at the bottom of the filter) taken the whole thing out, removed the filter, the drain at the bottom.

Made sure everything was set up right, that the o-ring was seated properly, and that the filter screwed into the assembly properly. Thought everything was going great, got it started, all was well.

Went to get some fuel, looked, and the nipple at the end of the drain at the bottom of the filter is dripping fuel. I don't know why it's dripping. Does anyone know what might cause this?

I am tempted to put the old filter back on there to see if that will work, any recommendations?

Should I try replacing the drain at the bottom of the filter? The leak is making me very nervous and I'd like to get it sorted out soon!

Thanks for any advice!

If I were you, I would take that plastic piece off, unscrew that nipple again and make sure that there is nothing stuck in there, failing that, buy a new plastic peice for the bottom or screw a small bolt into the opening of that nipple.

The leak is gone and the van is working fine now. The water drain unit was broken, I suppose the filter hadn't been changed in too long and me mucking about tipped it over the edge. Got a new water drain, it went in no problem, since then all's well. Thanks all!