I'm trying to set a record - an Expo with 225,000 miles on it, almost to the moon. It still runs great, burns very little oil - but in the last few days it doesn't start so great. After parking it for more than an hour it acts fuel starved and requires constant pumping to keep it going for a while - and the longer it's parked the worse it gets and the longer it takes, though the prob always goes away after constant pumping for a while (never more than 20 seconds), after which it runs great. When parked overnight I have to turn the motor over for about 10 seconds before it even tries to start. I suspect the fuel pressure is leaking down, and the first place I thought of to try to fix that is replacing the fuel pump regulator - but that didn't help. Next will be the fuel pump - but I'm not optimistic that will fix it either. I can't think of any sensor which would cause it to act fuel-starved for a duration directly proportional to how long it's been off. The only fault code I found was for a crank position sensor, but I hadn't dumped codes for years and I think that one was a red herring (if it was a bad crank sensor I doubt it would run at all). It hasn't output any codes since I cleared that one out. Any ideas?
Thanks. Gas yes. Fuel consumption seems fine - but haven't calculated. Cap, rotor, and plugs done within last 20K. Given how great it runs after 15-30 seconds of difficult start-up after sitting for an hour or so, I'm homed in on what happens when it's not running - I think fuel pressure is leaking down when off - but I'll admit it may be close-minded to jump to that. I'm guessing problem is either the fuel pressure regulator (replaced, no luck) or the fuel pump not holding pressure. So, fuel pump is next step, one's on the way. Injectors shouldn't be getting fuel when vehicle is off, and seem to run perfectly after 30 seconds, so I don't suspect them. I don't think it's throttle body for the same reasons as above - but I guess I shouldn't rule it out, it hasn't been cleaned in a millenia. If pump doesn't help, I guess I should at least look in there.
Yeah, I replaced the regulator several days ago - and symptoms stayed the same. Fuel pump's on the way now - I don't know how common it is to have a fuel pump that pumps fine but won't hold pressure after an hour of downtime - but if that's a common failure then there's a chance that will fix it. If the pump doesn't solve the prob I'm going to have to consult an expert - and hope they don't look at it as a science project for their next boat payment.
Could be the fuel pump itself - not the one in the tank - the one in the engine bay.
Fuel pump in tank pumps the fuel to the pump in engine bay and this pump provides the right amount of
pressure and fuel for the injectors depending on temp and rpm´s (basically)
Excess fuel is bled from the pump back to tank - desired cooling effect.
If that pump is bleeding the pressure to tank you would have a hard time starting - e.g. worn out seal etc.
Not sure if your regulator and pump are one unit ...
Thanks - but I don't see that this has a pump under the hood, the fuel regulator performs the function you're describing - and to me it's hard to believe a little skateboard of a car like this would require 2 pumps anyway.
But I'm starting to think I'm on the wrong track with fuel pressure bleed-off. For the second time it threw the code for crank position sensor, which I at first took to be a red herring - but it's really trying to tell me something so I guess I ought to pay attention. Mitsubishi says this has no crank position sensor, but told me the Alldata fault code listing says what provides the equivalent function is built into the distributor. My distributor is too inaccessible to dismantle on the vehicle, so it's easier to just replace the whole thing (I found a brand new OEM unit for $80). For future generations of Expo troubleshooters on the planet (all 6 of them) I'll post my results if I do that.
Mercifully, just before I irreversibly committed to the hail mary rebuilt distributor my ECU went flatline (i.e., the code for ECU failure). Not knowing whether that was my only problem, I knew I had to fix that first - and a quick google search on "symptoms of a bad ECU" indicated that certain ECU failures cause intermittent starting problems. So I put in a new ECU - and tada! I'm up and running. End of saga.
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