Cranks for 4-5 seconds before starting on first start then starts normally.

2011 MAZDA 3

172,000 MILES • 2.5L • 4 CYL • 2WD • AUTOMATIC

BROWNDOGG30

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My sons 2011 Mazda 3 has just started taking an abnormal amount of time to start. So it it cranks for 4-5 seconds before it starts and then starts normally until it sits for a period of time then in hard starts again. It has a new battery and a new alternator within the last year. Battery voltage static is 11.1 to 11.3v. Running is 13.8+.. Static voltage at 11.1 seemed a little low than normal to me so I thought maybe battery going bad and it hard starts until the alternator charges it and then starts fine until voltage bleeds down again and then hard starts again. I went got a new battery to test and the symptoms remain with the new battery. I had a mechanic tell me it’s probably the idle air control valve (IACV) but all my searches do not show an IACV even on this vehicle although I’m not 100% sure that is correct.

I swapped relays around for the fuel pump with other relays that are same part number and still the issue exists. I checked all fuel pumps fuses too. Pulled the throttle body off as it had major buildup. Cleaned it up reinstalled and idle is much higher than it was before but the start issue remains. I couldn’t hear the fuel pump prim8ng so I pulled the back seat out to access the the panel for the p7mp and removed the panel to see the top of the pump. I don’t hear the pump prim like you typically do just a faint click. I’m leaning towards the fuel pump but the access panel isn’t large enough to remove the pump meaning I’ll have to drop the tank to replace this. So I’m trying to rule out everything before shotgunning a fuel pump at it with no guarantee of it it being the issue.

I’ve had Autozone do a test of the starter, alternator and battery early 8n this process and all systems passed as normal. I was really hoping to find another issue other than the fuel pump but I fear that may be it. Unless there’s an IACV actually installed.

Any thoughts?

Dec 28, 2025 at 2:33 PM

CARADIODOC

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You're really going about this the wrong way. Throwing random parts at a problem is the most expensive and least effective way to find the solution. The only thing that raised my eyebrows is when you said you don't hear the fuel pump run for roughly one second when the ignition switch is turned on. That might be an issue with how the Engine Computer is designed. Some only run the pump once until the engine is rotating, (cranking or running).

The better place to start is by connecting a fuel pressure gauge, then run the hose under a wiper arm so you can watch it. What you're describing is typical of fuel pressure bleeding down over time, and that is usually the result of a leaking injector. Depending on the design of the fuel supply system, a fuel pressure regulator and the check valve in the fuel pump assembly can leak too, but those are very much less common.

If you are able to get multiple one-second bursts from the fuel pump, a simple work-around is to turn the ignition switch to "run", wait a few seconds, turn it off, wait a few seconds, then do that again and maybe even a third time, then crank the engine. If that makes a change for the better, suspect a drop in fuel pressure overnight.

Sometimes it takes too long to rebuild fuel pressure that has bled off. In some cases, simply pausing with the ignition switch in "run" for a few seconds provides extra time for that pressure to build, THEN crank the engine.

Generally, a leaking injector doesn't cause a problem while the engine is running, but over time, that fuel can wash down the cylinder wall, leading to dry piston rings at start-up. You can get a better idea with the fuel pressure gauge to see how bad the leak is. I know from experience on my '88 Grand Caravan, if fuel pressure drops from 45 to 20 psi, the engine still runs normally. It doesn't start to sputter until 15 psi. Compare that to some GM truck engines that won't start at all if fuel pressure is just 5 psi low.

If this does turn out to be a fuel pressure issue, this is one time when you might try a bottle of injector cleaner added to the gas tank. We don't normally approve of "mechanic-in-a-can" products except for special purposes. Years ago it was more beneficial, but for a number of years all gasoline has pretty good additives including detergents.

GM also used to have a really good product called "Top Engine Cleaner". It was added very slowly at first into the air stream, causing huge clouds of white smoke out the tail pipe. Towards the end of the can, the last was poured in fast enough to stall the engine, then you let it sit for a few minutes before restarting the engine. You might get lucky and dissolve deposits on the injector tips that are holding the valve open.

Dec 28, 2025 at 4:45 PM