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1998 Oldsmobile 98 starting problems

1996 Olds 98 Regency starting problems . When the engine is cold the car starts a little rough but smooths our and runs great. Once it’s been driven a bit and is hot, it will not restart. It spits and sputters and even backfires. I can pump the gas a bit and it’ll catch and run once in a while. But if it doesn’t, it floods and I have to wait about 10 minutes to try again. I’m getting these codes: p0131 - o2 sensor bank 1 sensor 1, and p0300 - random cylinder misfires, and I get another that says right bank running lean. The O2 sensor is new as of last weekend. I’ changed out the ignition control module a year ago and the helped for a while. Any suggestions?

Random missfires and lean Condition indicate fuel supply problem. When engine is cold, Turn your key to the run position (not crank position). Have an assistant near the gas tank. He should here the pump run for a few seconds. Turn the key off then back to the run position, wait five seconds or so then turn the key off. Repeat this 4 or 5 times. Then start it. If it starts right up, the first thing it could be is a bad fuel filter. It could also be a weak or leaking fuel pump. A fuel pressure gage can pinpoint it. It could also be a vacuum leak, but my first inclination is fuel.

The problem might be vapor lock.

Carry a bottle of water in the vehicle.

The next time the engine doesn’t start, take the bottle of water and pour it over the fuel rails. If the engine starts after doing this, that’s vapor lock.

Tester

And if it is vapor lock, that means you have a fuel pressure problem in your fuel injection system, either a weak pump or leaking injectors. I recommend getting the fuel pressure tested.

Holding the gas pedal to the floor while cranking should clear a flooded condition pretty quickly.

Thanks for the responses. I’m going to go ahead and replace the fuel filter and fuel pump.

Sure, why waste time an effort testing it first when you can waste time, effort, and money by replacing parts you might not need.

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If you are just going to throw money at it, why don’t you just invest in a fuel pressure gage. It will pay for itself, especially if you find your pump is good. You can learn online and here how to use it.

Well I did the suggested test of turning the key on for a few seconds about 5 times and it fired right up. That’s low fuel pressure, right? How is replacing the fuel pump then throwing money at it?

Could be low because of a leaking fuel injector. That would also explain the flooding problem.

My 1999 Honda has sometimes needed the “key dance” for most of its life - especially when the gas tank is near empty and the temperatures are very cold. As long as my wife and I know it may need that procedure, it’s a non-problem. There’s an anti-drainback valve in the fuel pump assembly and it probably leaks. A leaking fuel injector can also give that symptom.

Ok, how how do I check the fuel injectors?

If it were a leaking fuel injector, only one cylinder would flood. Then when the engine is started that cylinder would misfire. But other five cylinders would fire without a problem. And the engine would run really rough until the flooded cylinder cleared out.

So unless the engine runs really rough when started, it’s not a leaking fuel injector.

Tester

I’d find out the fuel pressure specs, hook up a pressure gauge, and see if it gets up to spec when running (if low, then fuel pump would be suspect), and if it holds pressure when shut off (if it drops, it could be a leaking injector, or a bad check valve in the system).

Well in driving on the interstate last weekend it was having trouble maintaining speed. The speed would gradually drop. Had to press the pedal to the floor kick into overdrive to get back to 75. That tells me it’s not maintaining pressure. It ran fine, not rough while this was happening and it’s when I got the O2 sensor code, right bank running lean codes. Does that help at all?

You could be right, first thing I’d replace is the gas filter, see if that helps.

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Or borrow one from your local auto parts store for FREE so you then know what the problem actually is.

Low fuel pressure can be caused by a restricted fuel filter. This is really going in the direction of fuel filter replacement.

Fuel pump’s in the gas tank, right? That’d be a bit of work to replace, I’d think. I’d guess the fuel filter would be easier to get to, and it is MUCH cheaper.

Filter is going on tomorrow. I’d venture to guess the pump will be going in next week
Thanks everyone