Hard Start when Warm

[tommyabward]

Have an issue with my 03 QX4. Cold and Hot starts are exceptional but after the truck has been sitting for 10 or 15 minutes it'll crank for a few seconds and then fire. Almost like a flood condition or a dead battery.

I replaced the FPR under the advisement of a friend and when we replaced it there was fuel in the vacuum line to the FPR. So it was clearly broken, but it still happens. He now seems to think it could be a fuel injector sticking.

Also, this is probably a coincidence ... but last monday I filled up the tank and forgot to close and click the gas cap and secure it. During that time, there were no startup issues. Cold, Warm, or Hot.

Any help or advice would be greatly appreciated. Thanks.

[centralcoaster33]

I'm not well versed in the idiosyncrasies of the Pathy, but what you describe sounds like an issue with fuel delivery. This could be due to pressure or vacuum build up from something not working properly in either your EVAP or Fuel Deliver system. I'd grab the Factory Service Manual (FSM) and start diagnosing the two systems, bit by bit. Fuel line and return line, FPR and it's vacuum line, pump, injectors, gas cap, EVAP lines, EVAP solenoids. Do you have the FSM? Sticky injectors might be able to be cleaned with an additive. You can check their resistance in Ohms to see if those are in spec. If it runs fine and starts fine the rest of the time, I don't think it's those very much, but maybe.

And / or, you can look for people with similar experience. I see one person who improved starts with a cleaned MAF, later they replaced their distributor and all was fixed. Older Pathy though.
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Another person with a 1995 Pathy ended up just needing a new starter, even though it mostly started fine when cold.

Another person had a bad battery that wasn't all that obvious except during warm starts. They had that tested at the local AutoZone and then replaced it.

This thread had all kinds of potential issues, one being a thing called IPDM that needed to be replaced. I didn't follow it very well, but maybe there are clues for you to glean.
05-pathfinder-turns-over-but-won-t-start-t471365.html