Advantages to turning ignition on before starting?

[manualman]

VW seems to agree that it's good to prepressure the fuel pump.

My Jetta runs the fuel pump for about 1-2 seconds every time I open the driver's door. Thus, the car gets the benefit of ramping up fuel pressure automatically before I even put the key in.

 

[SHOZ]

Well with the Fords the FP will only come on for 1 sec which each cycle of the key. When the engine starts the FP then goes back to normal operation. So this is not any abnormal cycling of the FP.

Floor the gas, crank the key, oil light goes out, take foot of the gas, the engine starts.

 

[Kestas]

SHOZ, I'm not sure about your last statement. Are you saying that flooring the gas during cranking will delay starting?

 

[cryptokid]

well i dont know if american automobiles tend to flood and need this "foot on the floor to diablle the injectors" dealie but my 96 mazda never floods, and putting my foot to the floor on startup only serves to make the engine start and instantly rev up to redline.

 

[DavoNF]

Kestas,

Yes, in all late model Fords, flooring the pedal will turn off the injectors, so you can crank as long as you like, it will not start.

Dave

 

[olddognewtrks]

FYI: My Mazda Protoge5 (and I've heard some other Japanese brands) kills the injector function if you floor the pedal BEFORE you crank it. This is supposedly programmed-in to clear out a flooded engine.(How does EFI flood? Spark plugs disconnected?)Letting off after you have begun cranking it re-enables the injectors and it starts. I found this on a Protege or Honda site, and used this technique to prime the filter and engine when oversized filters with bad ADBV's leaked the filter to dead empty (my filter sits slightly dome UP on the side of the block)and gave me nasty start-up rattles. This technique should come in handy for seldom-used or oil-change-not-full-filter situations

 

[S2000driver]

Here's what I've understood for fuel injected cars.

The fuel system is to "hold" fuel pressure so that the next time you start it you can crank it right away, and you will have pressure at the injectors even though the fuel pump is just getting started.

However, the longer the car sits the more the residual fuel pressure goes away. Therefore it becomes increasingly important to get the fuel pump running to pressurize the system while there is no load on the battery cranking the vehicle.

When you first turn the key to "ON", not the whole way to "START", the fuel pump will run to pressurize the system for about 2-3 seconds, then shut off. Any excess fuel pressure is sent back to the fuel tank by way of the pressure regulator and a return line. On Hondas, you can hear the electric fuel pump start and stop. The engine does not need to be running.

Therefore, in a fuel injected vehicle it's a good habit to pause for 1-2 seconds when starting the car to let the fuel pump pressurize the system.

[ January 29, 2004, 08:20 AM: Message edited by: S2000driver ]

 

[labman]

quote:

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Originally posted by S2000driver:
snip....
Therefore, in a fuel injected vehicle it's a good habit to pause for 1-2 seconds when starting the car to let the fuel pump pressurize the system.

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I'm not. As I said 4 weeks ago:
posted January 02, 2004 05:01 PM
Short on/off cycles will kill anything. Do you want to give your fuel pump and maybe other components an extra one each time you start the engine? Also, I would just as soon give the oil pump a few extra revolutions before the engine starts. This sound to me like one more way to mess around and cause more problems than you prevent.

 

[Stooge]

My Toyotas and fuel injected motorcycle (2000 VFR) all start with just a touch of the starter if I turn the ignition on, wait about 5 seconds and then start. I never touch the gas or throttle. In the Honda MC, opening the throttle always causes hard starting on the bike.

 

[S2000driver]

This is why I said pause at ON for 1-2 seconds then starte, since the fuel pump runs for about 3 seconds... so that the pump is not switched off and back on from waiting too long at ON.

I propose the benefits of having the fuel pump pressurize the system before cranking far outweighs the extra 1.5 seconds of the fuel pump turning. Your car will start up much more quickly and at the correct A/F ratio.

quote:

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Originally posted by labman:

quote:

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Originally posted by S2000driver:
snip....
Therefore, in a fuel injected vehicle it's a good habit to pause for 1-2 seconds when starting the car to let the fuel pump pressurize the system.

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I'm not. As I said 4 weeks ago:
posted January 02, 2004 05:01 PM
Short on/off cycles will kill anything. Do you want to give your fuel pump and maybe other components an extra one each time you start the engine? Also, I would just as soon give the oil pump a few extra revolutions before the engine starts. This sound to me like one more way to mess around and cause more problems than you prevent.

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[jsharp]

quote:

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Originally posted by SHOZ:
On Fords since 1992 the FP will run for 1 sec when the key is turned on. If your pump is worn this will help to build pressure to maybe cycle the key a couple of times. Also on Fords built since 1992 with FI if you crank the car with the gas pedal floored the FIs are turned off so the engine just cranks. This is kind of like priming the oil system.

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On my 5.0L Mustang the fuel pressure regulator is flaky and sometimes the fuel rail will bleed down when it sits a while. The 1 second pump run isn't enough to get things back to normal.

I "key it" a few times and it starts right up. Grinding it will just wear the starter motor out...

 

[Ma-fia]

The absolute easiest way to prime is to press gas pedal (all the way to the floor) 1-3 times before starting it or even putting the key in.
(If you keep doing it, the engine might get flooded though).
I do not know if this applies to all vehicles.

 

[S2000driver]

On a fuel injected car, pressing the "gas" pedal while the engine is not running does not do anything to the fuel. It simply opens and closes the air throttle butterfly.

quote:

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Originally posted by Ma-fia:
The absolute easiest way to prime is to press gas pedal (all the way to the floor) 1-3 times before starting it or even putting the key in.
(If you keep doing it, the engine might get flooded though).
I do not know if this applies to all vehicles.

---

 

[Ma-fia]

You're probably right; honestly I wouldn't know.
But it is true for carbureted vehicles (or at least the ones I owned...)

Ira

 

[labman]

How many of us still have carburetors? Starting was an art with them in very cold weather, and often knowing the idiosyncrasies of the particular car was important. Nearly everything at least required touching the gas pedal to take the pressure off the fast idle cam and allow the choke to close. Very many pumps, flooded many engines. Then there was my 71 Valiant that might take 20 when it was below 0. Hand chokes, stock or after market, were another skill.

I still have an old carburated truck. I have had FI cars since 1992, and it is hard not to give the gas pedal a kick when I get in however useless now. I guess it doesn't hurt anything. With 5W- oil and FI, I hardly even think much about cold weather starts.

 

[Rick in PA]

screwdriver in the choke plate...spray cans of ether...those were the days!

 

[ikeepmychevytoo]

My daily driver is carburated... It gives very reliable starts but weather is never colder than -15 celcius. Second time cranks are necessary on a specific heat range... this is usually on the autmn. Indeed the colder it is the more reliably it starts. But I know the reason: primary choke pull-off is acting a bit late, just not worth the effort to fix. Other than that it is nearly perfect. I'm happy with my Rochester.

But I guess I know what you mean. On manuals it says to push the pedal twice for very cold, and 2/3 for mild mornings. But it requires all the possible variations between those for any different morning. I flooded it last month... I'm still learning the best practice

.

Someday I'll fix that choke pull off for fun. My benchmark for the perfect carburetor is that I should be drive off as soon as or within 10 seconds it starts. Am I dead wrong? Weren't those cars this way when they were new?... I'm kinda young so can't remember those days well.

 

[labman]

Yeah, that is the way most people drove. I can remember people making fun of how long it took me to get my Dad's one Rambler moving. It had a push button automatic. You got in, put the key in and turned it to on, pushed the S/N button to start it, pulled out the Park lever below the dash, and then pushed the D button to put it in gear. By that time, all the key start, lever automatics were down the road. The Rambler did have an un-American Motors aluminium 327 CID V-8 with a Holley 4 barrel. I could catch up to them.