Won’t stay running

[Rinker85]

Hello, I have a 2001 5.7l GS. It won’t stay running unless the key is held on. I have 12 volts at the ignition switch on the red battery wire. I have 12 volts on the purple ignition wire when the switch is in the run position. I don’t have any voltage on the yellow Solenoid wire while in the run position. Looking at a post from 2016 with a similar issue, they said to jump the oil pressure switch. How do you do that when there is only 1 wire on it? Unless I’m looking at the wrong thing. Oil pressure is good when the boat is running. Any ideas?

Thanks

 

[itsathepete]

The yellow wire on the ignition switch supplies power to the starter solenoid when you are twisting the key to crank the motor. The oil pressure switch is not the same as the oil pressure sender. The sender has 1 wire and is located on the top rear of the engine by the ignition coil. The oil pressure switch is located on the port side of the engine below the exhaust manifold at the rear just above the oil filter. If you have a remote oil filter it is just above where the lines to the oil filter come off the engine. There are 2 or 3 wires on the oil pressure switch. One goes to the fuel pump, one goes to the alternator, and if there are 3 wires, one goes to the starter solenoid. When the starter engages (you are cranking the engine) voltage from the starter flows through the oil pressure switch and to the fuel pump or directly to the fuel pump, supplying fuel to the engine. When oil pressure picks up or the starter is no longer engaged, the switch opens this circuit and closes the circuit from the alternator to the fuel pump. This allows the fuel pump to continue running after the engine is started. If the oil pressure switch is not working properly, one or more of the circuits may not be functioning.
It sounds like the starter circuit fuel pump is working, supplying fuel to start the engine when cranking but the alternator circuit is not. If you jumper the wire from the alternator to the fuel pump, the fuel pump will run whenever the key is on, regardless of oil pressure. This should allow your engine to continue to run without holding the key and would indicate the oil pressure switch is faulty

 

[Rinker85]

The yellow wire on the ignition switch supplies power to the starter solenoid when you are twisting the key to crank the motor. The oil pressure switch is not the same as the oil pressure sender. The sender has 1 wire and is located on the top rear of the engine by the ignition coil. The oil pressure switch is located on the port side of the engine below the exhaust manifold at the rear just above the oil filter. If you have a remote oil filter it is just above where the lines to the oil filter come off the engine. There are 2 or 3 wires on the oil pressure switch. One goes to the fuel pump, one goes to the alternator, and if there are 3 wires, one goes to the starter solenoid. When the starter engages (you are cranking the engine) voltage from the starter flows through the oil pressure switch and to the fuel pump or directly to the fuel pump, supplying fuel to the engine. When oil pressure picks up or the starter is no longer engaged, the switch opens this circuit and closes the circuit from the alternator to the fuel pump. This allows the fuel pump to continue running after the engine is started. If the oil pressure switch is not working properly, one or more of the circuits may not be functioning.
It sounds like the starter circuit fuel pump is working, supplying fuel to start the engine when cranking but the alternator circuit is not. If you jumper the wire from the alternator to the fuel pump, the fuel pump will run whenever the key is on, regardless of oil pressure. This should allow your engine to continue to run without holding the key and would indicate the oil pressure switch is faulty

Thank you for the information. I’ll check it out when I get home

 

[Rinker85]

Thank you for the information. I’ll check it out when I get home

The yellow wire on the ignition switch supplies power to the starter solenoid when you are twisting the key to crank the motor. The oil pressure switch is not the same as the oil pressure sender. The sender has 1 wire and is located on the top rear of the engine by the ignition coil. The oil pressure switch is located on the port side of the engine below the exhaust manifold at the rear just above the oil filter. If you have a remote oil filter it is just above where the lines to the oil filter come off the engine. There are 2 or 3 wires on the oil pressure switch. One goes to the fuel pump, one goes to the alternator, and if there are 3 wires, one goes to the starter solenoid. When the starter engages (you are cranking the engine) voltage from the starter flows through the oil pressure switch and to the fuel pump or directly to the fuel pump, supplying fuel to the engine. When oil pressure picks up or the starter is no longer engaged, the switch opens this circuit and closes the circuit from the alternator to the fuel pump. This allows the fuel pump to continue running after the engine is started. If the oil pressure switch is not working properly, one or more of the circuits may not be functioning.
It sounds like the starter circuit fuel pump is working, supplying fuel to start the engine when cranking but the alternator circuit is not. If you jumper the wire from the alternator to the fuel pump, the fuel pump will run whenever the key is on, regardless of oil pressure. This should allow your engine to continue to run without holding the key and would indicate the oil pressure switch is faulty

Here are the pics of the oil sending and oil safety switch . But both only have one wire.

 

[Scott Danforth]

Yellow wire with red stripe is crank signal. You wont have wire there unless cranking

Check diode at alternator

 

[itsathepete]

Here are the pics of the oil sending and oil safety switch . But both only have one wire.

put a voltmeter or test light on the wire connected to the switch near the oil filter. if you have power to that wire with the key on, connect it to a ground and see if the fuel pump kicks on. If not, then replace the switch. If there's no power to the oil pressure switch with the key on, you've got another issue and you will have to trace out the wiring

 

[alldodge]

Yellow wire with red stripe is crank signal. You wont have wire there unless cranking

Check diode at alternator

Agree check the diode

 

[Bt Doctur]

On a volvo the alt supplies the power for the fuel pump

 

[Rinker85]

Yellow wire with red stripe is crank signal. You wont have wire there unless cranking

Check diode at alternator

How do you check the Diode on the alternator? Alternator is two weeks old

 

[Rinker85]

put a voltmeter or test light on the wire connected to the switch near the oil filter. if you have power to that wire with the key on, connect it to a ground and see if the fuel pump kicks on. If not, then replace the switch. If there's no power to the oil pressure switch with the key on, you've got another issue and you will have to trace out the wiring

The wire on the oil pressure switch only has power when cranking the engine

 

[Scott Danforth]

How do you check the Diode on the alternator? Alternator is two weeks old

You check voltage down stream

Your multi meter also has a diode setting

 

[alldodge]

How do you check the Diode on the alternator? Alternator is two weeks old

Diode is not in the ALT its inside the harness

 

[itsathepete]

Makes you wonder why the alternator needed replaced. Did a bad diode fry the alternator.

 

[itsathepete]

This should help explain it. Test before you start cutting into your wire harness.

 

[alldodge]

While the guy talks about if the other diode (not the one your issue might be) is causing engine to not shut off. This is "NOT" the way to fix that problem. There is a shorted diode and what does he do, he adds another diode to fix the current problem.

Issue with that is what happens when the diode that shorted out, opens up? Well someone is going to think its the diode he just installed and not look into the harness

 

[Scott Danforth]

99% of youtube videos have wrong information.

 

[Rinker85]

I’ve been posting for a couple of weeks with what’s been goin on. Let me condense it all right here because I think I had a couple of problems. End of June, drove the boat 2 miles at low speed then boat died. Would not crank. No voltage on meter. Previous owner busted the fuse block legs to add a chart plotter. Fuse box was flopping around And fuses were falling out. I replaced the fuse box and all connections. Replaced an 8 year old battery and install terminal buss connections on both battery’s. After all that the boat started fine but I saw the voltage was intermittently charging so I replaced the alternator. re started the boat and have a constant good charge of 13.5 volts When running. After running the engine up to operating temp, the engine died. Then I replaced the fuel pump relay and the socket. The socket was melted on the bottom. So after fixing all that I now have this problem where the engine won’t stay running unless the key is held on. Also the engine alarm should sound when the key is turned to on at first. It no longer does that. I just replaced the oil pressure switch and I’m waiting to start it up and test it. My 6 month old granddaughter is sleeping and the boat is right next to her window.

 

[alldodge]

What your saying is your not understanding what was said and shown in the drawings. In short , if the diode coming from the ALT has opened up internally, you have the same problem

 

[itsathepete]

While the guy talks about if the other diode (not the one your issue might be) is causing engine to not shut off. This is "NOT" the way to fix that problem. There is a shorted diode and what does he do, he adds another diode to fix the current problem.

Issue with that is what happens when the diode that shorted out, opens up? Well someone is going to think its the diode he just installed and not look into the harness

I agree he did not fix it properly and doesn't fully explain it but gives a little guidance on where to look for the problem. I should have either found a better reference or explained not to do what he did

 

[Rinker85]

What your saying is your not understanding what was said and shown in the drawings. In short , if the diode coming from the ALT has opened up internally, you have the same problem

If I find that diode how do I test it? Scott said there is a diode test on a multimeter. Mine doe not have that. Can’t I do a resistance test on it? Is this a common problem? Would this cause me to lose power at the helm back in June? And what about the melted relay socket?