Car hard to start sometimes

oldsmobile
alero

#1

Hello,

Vehicle is Oldsmobile Alero 2004, 3.4L V6, 160000 miles.

I’ve been having intermittent problems starting my car lately, maybe over the last month or so. What happens is when I turn it to Start it will crank and crank but not start. If I stop trying, wait a sec, then try again sometimes it works on the 2nd try, sometimes it takes 3 or 4 tries. I’ve never been unable to get it to start yet.

I didn’t think it was a battery/starter issue as it sounds normal just won’t start. The battery was old so I replaced it anyways but it didn’t make a difference.

It seems like it happens most often when its hot outside and I haven’t recently driven the car. If the car was driven recently and its hold or cold outside it always seems to start up effortlessly.

I have no noticeable drivability issues that I can tell. Also have no check engine light issues. Didn’t replace anything recently that would be related that I know of. I cleaned the throttle body to EGR port that was clogged and giving me PO401 a while back, but that was about 4 months prior to this problem starting so I doubt related.

From what I can tell from research theories are Fuel Filter (which has NEVER been replaced as far as I know), dirty fuel injectors (never been cleaned as far as I know), or faulty crankshaft position sensor.

Anybody have any ideas or recommendations? Any cleaner worth trying out as a first step? Any other likely cause of the problem?

Thanks!


#2

One more diagnostic step: turn the key to Run (not all the way to Start) and let the fuel pump run. You might hear it. After a few seconds it will turn off. Turn the key to Off, then Run, then wait a few seconds, then Off. Each time you do the “key dance” you are making the fuel pump bring up fuel pressure. When you then turn the key to Start, what happens?


#3

So I left work and it was nice and hot outside. I did the key dance three times, did what you described it would do (I can hear the fuel pump turn on, then off after about 2 seconds), and the car started right up. So I’ve had it start fine on hot days before, but if I do this the next few days and I see continual positive results what do you think that means? What if the opposite is true, that I see no consistent results from doing it?

Thanks!


#4

@shanonia had you test the fuel pump pressure - OK - and looked for a leak - Yes, you have one. The leak is internal. Either one or more of the injectors is leaking or the check valve on the fuel pump is leaking the fuel pressure down over the time it sits. Making you run the pump a bit (key dance) to pump the pressure up enough to start the car just proved it isn’t the fuel filter nor the CPS. Try a couple of tanks of gas with injector cleaner added. That might make the problem go away. If not, it is more likely the fuel pump check valve. Since the car has 160K, the pump may be on its last legs anyway so change it.


#5

I’d follow Mustingman’s lead. Click and Clack recommend fuel system cleaner that has Techron in it, and I’ve seen at least one such brand in the stores over the years. If it’s a leaking injector, that stuff might clean it and restore its function.

As long as you and any other driver know the key dance, and it works, you can choose to delve further into repairing it, or let it be.


#6

I’ll second the Techron suggestion. I used to have a Taurus SHO with that would develop the same starting problem about every 18 months. One bottle of Techron would clean it right up. Not a commercial, just personal experience. Other products can perform the same task.


#7

Ok great guys, thanks for the help. I’ll try the Techron first and if it still acts up I’ll replace the Fuel Pump most likely.

Thanks!


#8

The test you did proves it the fuel pump.


#9

If you are talking about the “key dance” as the test the OP did, I don’t think if proves it is the fuel pump at all. That points to losing fuel system pressure and having to trick the pump into pressurizing the system so the injectors spray fuel.


#10

I’d agree you are losing fuel pressure but the question is whether its from a stuck injector, the check ball, or the pump itself.


#11

OP needs a fuel pressure leak down test. Why guess? It’s a fairly simple thing for a shop to prove one way or the other whether the fuel pressure is holding like it should or not after the engine is shut off.


#12

The thing is all a pressure test will tell you is that you are losing pressure. It doesn’t tell you where. Seems to me as a test, if you pinched off the return hose and still lose pressure it would be an injector. If not the check ball or weak pump.