Car cranks for a time before starting

Tiny
JOSEPH CROSSMAN
  • MEMBER
  • 2000 CHRYSLER CIRRUS
  • 2.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 115,000 MILES
My car would crank over a long time before starting. My garage installed a new fuel pump after which the problem still existed. The mechanic suggested that we change the starter. Before doing that I felt I should get a second opinion. The next garage tested the fuel pump and found that the new pump was not holding pressure and suggested that I take it back and have it replaced. My question is, if the fuel pump was likely to be the problem in the first place or the starter the likely problem or is it likely that the new fuel pump is faulty? One year ago I replaced spark plugs, wires, valve cover, gaskets, distributor cap and rotor.
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Friday, January 10th, 2020 AT 11:50 AM

3 Replies

Tiny
CARADIODOC
  • EXPERT
None of these are good suspects. The most common cause of long crank time is a leaking fuel injector. It can also be due to a fuel pressure regulator leaking pressurized gas back to the gas tank on the return line, or a leaking check valve in the fuel pump, but both of those are very much less common. The leaking regulator can be identified by using a hose pinch-off pliers to pinch the fuel return hose where it transitions from the body to the engine.

How long do you have to crank the engine before it starts? The place to start is by connecting a fuel pressure gauge, then watching what happens to fuel pressure over time when the engine is not running. If it drops almost instantly when the engine is stopped, you might suspect a cracked rubber o-ring on the fuel pressure regulator. I've run into that twice including once on a brand new car fresh off the hauler, and once on a high-mileage car, and the customer didn't want to spend the 39 cents for a new o-ring.

The next question is how long does it take after stopping the engine before you have that long crank time again? With a leaking injector, it is common for the engine to restart normally after as much as a few hours, but rarely after sitting overnight.

When you turn on the ignition switch, you may hear the fuel pump's hum for one second. That is supposed to be enough time to get the fuel pressure up for starting in case it bled down over days or weeks, but when it has bled all the way down to nothing, that one second isn't enough time. The way I overcome that long crank time on my minivan is to turn the ignition switch to "run", then wait until the fuel pump stops running, then crank the engine. Some people have good luck by turning the ignition switch on for a few seconds, back off, then on again, then they crank the engine. That gives the pump twice as much time to build pressure. The engine won't start until the fuel reaches a certain pressure.

When you quickly turn the ignition switch from "off" to "crank", it is normal for the starter system to draw the battery's voltage down to as low as ten volts. That lower voltage causes the fuel pump to run slower than normal, so it builds pressure slower than normal. Along with that, even though the engine hasn't started running yet, what little fuel pressure exists is being bled off by the injectors firing as they're supposed to. Some gas is dribbling into the engine, but not enough to make it run. By being bled off during cranking, you have a double whammy. Pressure builds too slowly and what's there is being bled off.

You might also try something as simple as buying gas from a different station. Even the cheapest gas today has a lot of additives to clean the fuel systems, but sometimes switching to a different brand will get you a different formulation of those additives, and that might be just what is needed to clean a needle and seat in an injector that's leaking. That leakage is not nearly bad enough to cause a running problem, but the long crank time it causes can be irritating. If that works, it isn't going to solve the problem right away.
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Friday, January 10th, 2020 AT 5:04 PM
Tiny
JOSEPH CROSSMAN
  • MEMBER
Thank you. The info gives me some understanding of what is happening so that I can talk intelligently with my mechanic.
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Saturday, January 11th, 2020 AT 6:43 AM
Tiny
CARADIODOC
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Please keep us updated on your progress.
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Saturday, January 11th, 2020 AT 1:41 PM

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