Preventing ignition

[sfkjeld]

Can someone tell me if there is a fuse that controls ignition for a 2000 2.7 car? I’d like to be able to spin the motor with the starter but prevent the engine from actually starting.

[JFP in PA]

Originally Posted by sfkjeld

Can someone tell me if there is a fuse that controls ignition for a 2000 2.7 car? I’d like to be able to spin the motor with the starter but prevent the engine from actually starting.

Take either the fuse or relay for the fuel pump, bleed off residual fuel pressure and it won't be able to start.

[sfkjeld]

Thanks, but it sounds messy. Is there a fuse in the ignition circuit?

[blue62]

Originally Posted by sfkjeld

Thanks, but it sounds messy. Is there a fuse in the ignition circuit?

There is a "presta" valve on the fuel rail, It's like a valve on your tires.
push it with a screw driver while holding a rag over it.... done.
JFP gave you sound advice..... if you crank the engine over without disabling the fuel system and relieving the fuel pressure your going to be putting raw fuel into the engine....... washing the oil off the cylinders and bearings...... Not good for the engine.......
Then pumping raw fuel into the exhaust and possibly damaging the catalytic converters.
If you want to know the location or type of specific fuses or relays they are listed in the Bentley book.
I believe fuel injectors and ignition are the same fuse.

[sfkjeld]

Thank you. I hadn’t thought of that. Where is the “presta valve” and the fuel rail? And once I’ve pressed the valve, do I need to do anything to re-enable the fuel supply?

[sfkjeld]

Wait, so there is a fuse that supports both ignition and fuel injectors? If so, why not just remove that fuse?

[blue62]

Originally Posted by sfkjeld

Thank you. I hadn’t thought of that. Where is the “presta valve” and the fuel rail? And once I’ve pressed the valve, do I need to do anything to re-enable the fuel supply?

Look at the engine the fuel rail feeds the fuel injectors. If you know anything about engines you can't miss it. The presta valve is in the fuel rail it typically has a brass cap or plug over it.
When you replace the fuel pump relay or fuse and go to restart the engine for the first time just turn the key to the on position a wait a few seconds and give the fuel pump a chance to re-pressurize the system before engaging the starter.

[blue62]

Originally Posted by sfkjeld

Wait, so there is a fuse that supports both ignition and fuel injectors? If so, why not just remove that fuse?

well I have no idea what it is your trying to do so I couldn't say.

[JFP in PA]

Originally Posted by sfkjeld

Wait, so there is a fuse that supports both ignition and fuel injectors? If so, why not just remove that fuse?

Because if you just remove the fuse, you will be still pumping gas into the engine while it is turning over, which is not a good idea; if you disable the fuel system and vent off the residual pressure, you will prevent gas washing over the cylinder walls and into the oil sump, which is a primary cause of bore scoring.

[blue62]

Originally Posted by JFP in PA

Because if you just remove the fuse, you will be still pumping gas into the engine while it is turning over, which is not a good idea; if you disable the fuel system and vent off the residual pressure, you will prevent gas washing over the cylinder walls and into the oil sump, which is a primary cause of bore scoring.

I tried to get that through to him I guess he didn't get it.

[JFP in PA]

Originally Posted by blue62

I tried to get that through to him I guess he didn't get it.

Sometimes, people only hear what they want to hear. It's his car and his money, so he is free to do whatever he pleases, but I often wish people would learn to think like doctors when working on these cars: First, do no harm..........

[sfkjeld]

Wait, that’s a bit harsh, no? I said I want to turn the engine over with the starter, without the car starting. It’s been in storage for months. I want the oil to circulate just a bit before the car starts.

Yes, I was hoping there was a way to cut the ignition only. I get the issue Blue brought up, with raw fuel dumping into the cylinders. Tho in this case, I doubt it will matter since the engine won’t need to spin much. And I would only need it after its winter storage.

I appreciate your help. But not necessarily your tone.

[blue62]

Originally Posted by sfkjeld

Wait, that’s a bit harsh, no? I said I want to turn the engine over with the starter, without the car starting. It’s been in storage for months. I want the oil to circulate just a bit before the car starts.

Yes, I was hoping there was a way to cut the ignition only. I get the issue Blue brought up, with raw fuel dumping into the cylinders. Tho in this case, I doubt it will matter since the engine won’t need to spin much. And I would only need it after its winter storage.

I appreciate your help. But not necessarily your tone.

You would be doing more damage with the raw fuel issue then any wear you would deminish by spinning the engine to circulate the oil before starting.
If you truly feel the need to circulate oil before starting after winter lay up then you should consider installing something like an acu sump system they are designed for that purpose.

[blue62]

Originally Posted by JFP in PA

Sometimes, people only hear what they want to hear. It's his car and his money, so he is free to do whatever he pleases, but I often wish people would learn to think like doctors when working on these cars: First, do no harm..........

Spot on......

[piper6909]

Originally Posted by JFP in PA

Sometimes, people only hear what they want to hear. It's his car and his money, so he is free to do whatever he pleases, but I often wish people would learn to think like doctors when working on these cars: First, do no harm..........

Being an impartial observer, I don't exactly think that's the case here. SFK was inquiring about the fuse that fed both the ignition AND the fuel injectors. It doesn't necessarily mean he didn't understand or listen to what Blue said about fuel in the cylinders.

Now here's MY take, and please tell me if I'm wrong:
1) The car was sitting all winter, so I seriously doubt there's any significant fuel pressure in the system anyway. Just pulling the fuel pump fuse or relay should suffice.

2) Even if there IS fuel pressure, and here's where SFK's question comes into play, if the fuse that powers the injectors is pulled, then the injectors can't pulse and inject fuel into the cylinders anyway. Correct?

[JFP in PA]

Originally Posted by piper6909

Being an impartial observer, I don't exactly think that's the case here. SFK was inquiring about the fuse that fed both the ignition AND the fuel injectors. It doesn't necessarily mean he didn't understand or listen to what Blue said about fuel in the cylinders.

Now here's MY take, and please tell me if I'm wrong:
1) The car was sitting all winter, so I seriously doubt there's any significant fuel pressure in the system anyway. Just pulling the fuel pump fuse or relay should suffice.

2) Even if there IS fuel pressure, and here's where SFK's question comes into play, if the fuse that powers the injectors is pulled, then the injectors can't pulse and inject fuel into the cylinders anyway. Correct?

Two things: I saw nothing in his original question that would indicate the car was "sitting all winter", and we have seen cars that have been sitting for very long periods that did have pretty substantial residual pressure in the fuel system. By spec, the car should hold around 55 PSIG pressure for long periods while sitting..

You are correct that pulling the fuse for the injectors should prevent fuel flow, but as we do not know the reasons why the op is even doing this test, the general systems condition of the vehicle, or how technical he or she is; bleeding off the pressure first is simply a guarantee that they will not create other problems while completing whatever they are working on.

[blue62]

Originally Posted by piper6909

Being an impartial observer, I don't exactly think that's the case here. SFK was inquiring about the fuse that fed both the ignition AND the fuel injectors. It doesn't necessarily mean he didn't understand or listen to what Blue said about fuel in the cylinders.

Now here's MY take, and please tell me if I'm wrong:
1) The car was sitting all winter, so I seriously doubt there's any significant fuel pressure in the system anyway. Just pulling the fuel pump fuse or relay should suffice.

2) Even if there IS fuel pressure, and here's where SFK's question comes into play, if the fuse that powers the injectors is pulled, then the injectors can't pulse and inject fuel into the cylinders anyway. Correct?

Couple of things:
First:
it's a forum.... a computer screen situation where a reader has to make assumptions.
The first and main assumption I make if a poster comes to a forum to ask about something as simple as a fuse, a relay or the location of such, I assume that they are not very knowledgeable about their car.
Second:
Then if they ask a question like where is the fuel rail????? That just re-enforces my assumption that they have zero mechanical knowledge.
The only other info given is that he wants to crank the engine over without it firing.

So if you want to help that person with the very limited information you have from that poster... what do you tell them????

JFP in PA had the perfect line "think like a doctor do no harm"

The best way to do no harm is to do what JFP suggested completely disable the fuel system.

[piper6909]

Originally Posted by JFP in PA

Two things: I saw nothing in his original question that would indicate the car was "sitting all winter", and we have seen cars that have been sitting for very long periods that did have pretty substantial residual pressure in the fuel system. By spec, the car should hold around 55 PSIG pressure for long periods while sitting..

You are correct that pulling the fuse for the injectors should prevent fuel flow, but as we do not know the reasons why the op is even doing this test, the general systems condition of the vehicle, or how technical he or she is; bleeding off the pressure first is simply a guarantee that they will not create other problems while completing whatever they are working on.

Yeah, if they would have said from the onset that the car sat in storage for months, AND the actual reason for not wanting it to start, then things may have gone differently.

I have no beef with you or Blue. I just didn't get the impression that they "only hear what they want to hear." Maybe I had the advantage of seeing all the posts.