I have a 1987 Nissan Pathfinder with almost 300k miles on it. I have driven it daily and across country for the past 3 years. The other day I went to start it, after it turned (barely) the RPMs jumped up and down before choking out. I started the car a couple more times and the same thing happened so I let it sit for a couple days. Since then when I start it, it either does the same thing or runs fine. I’m wondering if maybe it’s the fuel pump?
The “barely turned” fits with a weak battery. The “car choking out” fits with water in the gas tank and/or a bad fuel filter. I would eliminate the quick and cheap before getting to the in-shop stuff like fuel pump. Put a bottle of gas dryer in the tank, change the fuel filter, test the alternator output and test the battery’s ability to hold a charge. 300,000 miles - good for you. I have a 1992 Subaru at 300,000 miles and still flying. But expect to live with the worn-out parts problems. I had a worn out ignition and drove myself nuts fooling with the electrical under the hood before it hit me - I’ve turned the key so many times its shot. PS Testing the fuel pump is quick and cheap too. If the pump needs replacement, ask the mechanic what else he can replace as long as he is in there.
I agree with Horse here but might add that I would clean you battery terminals clean and shiney, and while you’re cleaning things see if this has an electric choke and go ahead and clean everything concerning the choke . . electrical ends and stuff, all that is connected to the choke. I’d give the carb a dose of carb cleaner around the linkage also. If the battery is weak, the cleaning won’t help but you’ll know that you need a battery and you’ll have clean connections. The carb cleaner around the choke and linkage might get rid of any gunk screwing up your ability to run it. Good luck. Rocketman