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I have a 2002 Mazda B3000 (essentially a Ford Ranger) that almost never starts on the first attempt. Usually it takes 2 or 3 tries before the car finally turns over. Each time I hold in the crank I hear the starter engage and the engine whir but the car doesn't start.

I've tried cycling the key to iginition on, waiting for a 10 seconds, then back to off several times to try and prime things but that does not seem to help.

I ran Seafoam through the gas lines to try and clear up any carbon deposits but this also has done nothing.

I have taken it to a mechanic twice, both times they were unable to reproduce the problem which blew my mind since it happens about 95% of the time I try to start the vehicle. They tested the fuel pressure and told me it was normal. This may be anecdotal, but I notice that if I stop the car and then start it again pretty soon (within 10-15 min) after it has a good chance of starting right away on the first try.

Edit:

I cleaned my mass air flow sensor to no avail. As an added detail, when the car does start it usually begins right away or revs really low and then gets up to idle in a second or two. Sometimes it will rev low and shut off.

Edit 2:

You can see my response to my own question below. It was discovered that both the mass airflow sensor and the throttle sensor were faulty and needed to be replaced.

  • Any engine codes to share? – race fever Jan 4 '16 at 23:10
  • 1
    When you say it won't "turn over" ... do you mean the starter engages and the engine whirs but doesn't want to start? Or do you mean no starter noise at all? I'm thinking may be the check ball in the fuel pump may be bleeding off pressure. In this case, most of the fuel in the gas lines goes back into the tank after you shut it down. The pump will run fine and provide the pressure, but it can take several time for the fuel to get pressurized. Just guessing here, though. You'd have to put a fuel gauge on the rail and see how it behaves over time to really tell. – Pᴀᴜʟsᴛᴇʀ2 Jan 5 '16 at 1:06
  • No check engine light is on so I haven't yet checked engine codes. What i mean by turn over is what you mention first - the starter engages and the engine whirs but it doesn't start. As a followup, I took out my mass air flow sensor and cleaned it with MAF cleaner and replaced it with no better results. I'll look into testing the ball in the fuel pump though I'm an amateur (at best) at these sorts of things. – James Bilous Jan 5 '16 at 1:38
  • You need to check the fuel pressure and make sure to verify the readings. They might have checked and say its normal, but they could have done a quick test. You need to test the pressure with the engine at operating temperature. Try to replicate standard operating conditions as closely as possible. This sounds like a bad fuel pump or bad fuel pump relay. But without those readings its hard to say. – race fever Jan 5 '16 at 3:28
  • When I said check the pressure over time, what I mean is to put a fuel pressure gauge on the rail, run the engine, ensure pressure is good, then shut the engine off and observe the pressure over several hours. If the pressure doesn't hold, it can be one of two things: bad check valve in the pump; leaking injector(s). Either one with cause hard starting, though both exhibit different symptoms. – Pᴀᴜʟsᴛᴇʀ2 Jan 5 '16 at 12:59
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The mystery was finally solved after taking in my vehicle due to a check engine light before a smog test.

Both the mass airflow sensor and the throttle sensor needed to be replaced as they were giving faulty readings which caused high idling on top of the cold start problems. I did clean the mass airflow sensor, but apparently this wasn't good enough since it was faulty. Thanks for all your guys help - I'm glad it wasnt the fuel pump.

EDIT: Turns out that the problem is still happening even after replacing both the mass airflow and throttle sensors. The issues were just exacerbated by the fact that not enough oxygen was getting into the mix. My mechanic and I are very confident that the issue is the fuel pump, whether it due to be the check valve or some other aspect is unsure. I'm going to ride it out until its a real problem, the issue hasn't been getting worse.

2

I'll bet you have a leaky fuel pump check valve. As you sit, it slowly allows the pressure from the fuel line to bleed back into the tank. You have to crank the engine over long enough to build up pressure to pump the fuel from the tank back up to the engine. I'm guessing you'll wind up replacing the fuel pump, as the check valve is usually built into it and isn't available separately.

  • I just installed a new Hella fuel pump in my 2004 Ranger after the original failed (1 day, no symptoms, next day complete failure). Now I'm having the problem described here. Is there any danger/problem with ignoring the possibility of a leaky check valve other than the frustration of multiple cranking? – Bill N Jun 8 '17 at 13:52

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