Well the problem has recurred.

Daughter again went to store. Tried to start it to leave and it would stumble and not start for her. I got there and same thing - engine starting to fire yet stumble. Feathering the gas pedal while cranking and it started up and stayed running. Rougher than normal idle (engine has cylinder 6 misfire) and idle seems lower than normal (600-700 rpm). AC not on.

Drove home fine. When parked idle again seems lower than normal.

Need to drop of for safety inspection today. Will futz with it over the weekend.

Last time this occurred the only engine code was the P0306 cylinder 6 misfire which unfortunately is normal for this thing.

Where else are there fuel filter type elements? Seems fuel related.

 

Larry.......Mann, bad luck. I havent read the entire story, so sorry if I am asking a dumb question: Have you pulled out the fuel pump and checked the flat long filter on that? Maybe that filter is getting clogged? Also could be the fuel pump going bad?

 

No I have not pulled the fuel pump to check that filter. As nasty as the other one was, I can see this one as being bad as well.

I also have not checked the fuel rail pressure which is how I assume one assesses the performance of the fuel pump.

I have not read up on this so I guess its time to start getting smart on this. Unlike the fuel size Montero's, it is my understanding that the Sport does not have the access plates on the floor of cargo area so the tank needs to be pulled.

Oddly, I just hopped in it, started right up, idled its normal self, and drove it off to the service station for safety inspection without issue. I hope to pick it up tomorrow. I failed to think of trying a hot restart.

In thinking about it now, for me today without issue it was the first time running of the day. In both of my daughter's stranded cases, they were both hot restarts after a brief stop at the store. Maybe this is a clue somehow.

Edit - just watched this video and short of not having a lift, the fuel pump replacement looks rather straightforward,

This appears to be the fuel pump assembly from the above video. Airtex E8439H Fuel Pump Hanger Assembly

 

Larry.....I watched the video of the tank removal......doesnt seem too bad, except maybe getting your fist into that tight area above the frame to disconnect the lines and quick-connect fitting (kinda a trick knowing where to push/pull those connectors to allow them to come off).

To check the fuel rail pressure, I think you can just open the line someplace near the fuel rail and put a capture container to catch the gas being pumped.......then turn on the key and just see how fast its coming out. If its pumping out at a decent clip, the pump should be fine, but if its just dripping/drizzling some, then there is either a clog somewhere or a bad pump. If you have a fuel pressure gauge, I suppose the proper test is the best, but sometimes you can wing it.

Im wondering how hard it would be for you to cut an opening above the fuel pump, and make a cover......so next time you dont have to remove the tank. The cover on the old Monteros is a bit small, making it a little tight working.....if I had designed it, I would have made it twice as large.......shoot, even use hinges for a "fast access/fast replacement", and maybe secure a back-up Colt 45 in there for the coming economic collapse. (ha ha)

Since its working good on cold starts, then maybe that "down time" allows some pressurized gas to get thru the clogged areas and to the fuel rail, and thus it runs good initially. But then, the fuel does not keep caught-up with the usage, and then you have problems. Maybe the hot engine also contributes somehow.....maybe the clog is up near the fuel rail, and the heat expands the area making the fuel more constricted in its flow???? Just a wild idea. But it does sound like either a bad pump or a clog someplace.

 

Passed safety inspection.

Started up and drove home fine from inspection station.

Still pondering next moves....

 

I think if you replace fuel pump once, it should last for close to as many miles as you got on your Montero already. I doubt you'd need to do it ever again (hence no need to do a swing out hatch in the floor). One thing just came to mind - vehicle runs OK on cold start, but starts acting up when hot... If you think about it, the pump motor will get hot after running for some time. It's possible that it some internal contact or something else creates an open circuit when pump heats up. I don't know how you'd test that, except to plum in a fuel pressure gauge into the fuel system and drive around. If you see a fuel pressure drop when engine starts acting up - you know pump quits on you.

 

That sounds like a great idea by Hunter........it sure would be nice to see a gauge in the dash showing fuel line pressure.......Ive got a factree altimeter and inclination gauge, so why not toss in the gas pressure too? Havent yet found my rear flaps control, so Ive been forced to keep her on the ground, mostly.

But Hunter might be spot-on with the theory that the pump is getting hot after running, and then failing.

If you didnt want to drop the tank, one idea would be to rig up another small gas can with an electric pump and a line tapping into the fuel line someplace. Ride her around with that set up and see if it acts up again. Dont forget to pull the relay to the stock fuel pump so it wont be running during the experiment.

 

You laugh, but I actually did rig a fuel pressure kit with the gauge sticking out from under the hood by the windshield on my other car (when it was acting like it was fuel starved). Drove around with that and I could see fuel pressure "live" feed. Helped me to figure out that high pressure fuel pump was not good.
The only issue is that Montero doesn't have a ready port for fuel pressure testing. Perhaps in earlier models you have some place you can tap into a rubber tubing, but my 2001 model - no such luck. It requires a special adapter to add inline between fuel line input (metal tube) and the fuel rail.

 

I agree with Hunter that there is no need to make an access hatch/cover for the fuel pump - If replaced it should last for a long time. Agreed that a factory access cover would be nice. The Youtube video showing how to drop the tank doesn't seem to be too hateful. I had to remove the fuel tank on my Ford F350 to replace a rusted brake line and did it in an afternoon.

Seeing how the fuel filter was crudded up like it was when I replaced it, I am thinking that the fuel pump sock/strainer (or whatever you call it) in the tank may be similarly restricted. Perhaps the sediment jostles around?

This guy did a qualitative fuel pump test - turn key quickly from off to start position (ie - don't give fuel pump a head start) and his engine would crank for bit then finally start. If he turned the key first to run, waited a bit, then to start it would fire right up. The premise being the delay in cranking allowed the pump to build pressure in spite of clogged components. However as is too often the case, the OP vanished and never reported back with his findings and solution. I will test this out today.
https://mitsubishiforum.com/forum/mi...-filter-45239/

This link is for a pajero (montero offshoot) and guy had clogged fuel pump strainer but his symptoms were different (stumble while driving - vs hot restart issue). In retrospect, I do recall driving it and getting an occasional stumble while accelerating and taking foot off the pedal and then reapplying the pedal and the engine would smooth out. This appears to be more in line with his findings.....
https://www2.pajeroclub.com.au/forum...ad.php?t=48701

I think I am steering myself towards pulling the tank to replace the pump and sock/strainer and clean the tank out.

Edit - it appears from the manual that the fuel tank should have a drain plug....

 

Larry, the posts you link surely sound like they describe what is happening with your vehicle. When you drop the tank, check if its excessively rusty inside. I've dealt with a car (now my daily driver) that would not run at all when I bought it. It turned out that the fuel pump was a solid lump of rust and the inside of the tank was very corroded. Not wanting to splurge for a new tank, I used KBS fuel tank coating to fix the rust in tank. That stuff worked like magic. I owned the car now for 7 years and there is not a speck of rust in the tank (I know because I had to replace a faulty sending unit, so I got a chance to look inside not long ago).