Please Help!

I have a 98 MPV V6 4WD with about 160k

It had an oil change, lube and winter service/inspection package at the dealer about 300 miles ago - they didn't note anything unusual. It's been driving fine for the last few hundred miles, then just suddenly stalled out while driving at 35mph.

It wouldn't start again for a couple hours, then it did start up and I drove it about half a mile before it died once more. The condition was: it was idling fine, but when it was given any real gas to accelerate it would choke, the RPMs would drop, and if I let it coast it would stabilize a little. Eventually it died altogether and wouldn't start.

A relative said it sounded like a clogged fuel filter. Installed new fuel filter in the parking lot, brown fluid, then a tiny bit of black, discharged when removing the filter. With the new filter on it started right up and revved great, just like the whole problem was solved.

Went about half a mile and it started choking little again, getting progressively worse over the next mile, then it died. Restarted several times, noticed the more gas you give it (even just a little), the quicker it is to choke. Wouldn't start at all. Towed it home with a tow rope at night.

Checked the flow of gas after the filter (into a bucket) with the key at "start" - definitely more gas than it could possibly burn in the duration. Flow seems visually solid.

First note: the fuel pump does NOT pump with the key at the "on" position, which the Haynes manual says it should (though I've caught a few things wrong in the manual).

Filled the tank with Chevron Supreme - fresh/quality gas in the lines.

Installed new K&N air filter and Bosch spark plugs (Platinum +2, factory gapped).

Installed a new Fuel Pump Relay. No change.

Installed a new Fuel Pump. No change.

Note: fuel tank appeared clean and shiny from the fuel pump port - no debris, gunk or rust.

Current condition: if the car sits for an hour, it can be started fine, there's plenty of "whirring" with an ear to the fuel pump (while the engine is running), the MPV idles fine for a minute or two (max) then it starts choking a little, progressively faster choking over a minute (still at idle), then dies. If it's restarted in a couple minutes, it will do the same but only run for 20-30 seconds before choking to a stall. When it dies, the fuel pump runs for another few seconds, then shuts off.

OBD-II Codes Present:
P0420 Catalyst System Efficiency Below Threshold (Bank 1) - [code was there before this event]
P1345 No CMP or SGC Signal - "camshaft position sensor" - [code appeared when checked after this event began]


I live over 100 miles from a dealer, so no joy there.

If anyone can help it would REALLY be appreciated!

Thanks!


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Update:

Cleaned the mass air flow sensor with the specific cleaner. (as recommended by dealer)

Replaced the distributor cap and rotor. (old ones had corroded contacts)

Added red-bottle Heet to fuel in case water is in play. (helped someone in another thread)

Was unable to find the ignition coil (per the Haynes manual) for resistance testing. There is no coil wire to trace - it's built into the distributor cap, with direct contact into the distributor.

Was unable to find the cam position sensor (per the Haynes manual) for resistance testing. There is no square 4-wire (or similar) connection visible anywhere on the distributor. This is the only OBD-II code coming up now, though at least three sources have said this part will not cause the engine to stop, only reduce performance.


Current condition:

The vehicle will start easily cold, will then idle great for 5 minutes, then it starts to choke and eventually dies. Have repeated this test 3 times today, with 1-2hrs between test, same result every time.

The fact that it runs just fine for 5 minutes seems to say the engine is quite capable of running well.


Next steps???

Considering if buying a Fuel Pressure Tester is needed to test the:
* Fuel Pressure Regulator
* Pulsation Dampener
* possibly the hose feeding the fuel injection rail, though access is questionable - there doesn't seem to be a test port on the rail itself.

Accessing the fuel injectors requires removing the Variable Resonance Induction System, intake manifolds, etc - serious work and Mazda replacement gaskets required.

So far nothing replaced on the fuel supply side has helped.

The Mazda dealer service department head guy thinks (just from verbal description) it's probably the distributor failing. However, the distributor powers the engine great for 5 minutes, so I don't see how it would suddenly fail completely after this interval, every time.

A Kragen manager thinks it's a sensor (though codes should show up) or possibly bad fuel injector o-rings.

I'm suspecting some sensor somewhere (fuel, air, ignition), but there are no OBD codes coming up (other than the P1345 already mentioned) and a service expert with MPV experience (to actually test whatever sensors could be in play) is nowhere nearby.

. . . really need a plan for solving this . . .

. . . please . . .

 

check fuel perisher regulate and try replacing the rubber fuel lines