Ignition problem on 5.7

[magic11305]

My on going project . I have a 2008 5.7 vortec Michigan Motors engine, no serial number, which I have rebuilt. I got it installed in the boat and started her up, purred like a kitten. I came across a couple of issues that I hope someone can help me figure out. First of all, when I turn the key to the off position, the fuel pump stops but the engine continues to run. It starts fine with the key but I have to choke it out to kill the engine??? Also, don't know if it is related, but my oil pressure guage is pegged all the way to the right, and the fuel guage peggs below empty when the key is turned on. The tach and temp seem to be working fine. It has a Delco Voyager EST ignition. I know I have a wiring problem but I'm hoping you guys can give me some ideas where to start. Thanks

 

[tazrig]

Re: Ignition problem on 5.7

Are the ohms ratings the same on the sending units as on the gauges?

 

[magic11305]

Re: Ignition problem on 5.7

I didn't have enough daylight this evening to get started with tracking down the problem. I plan on working on it tomorrow, I was trying to do my homework tonight so I have some ideas when I get started. Thanks for the reply tazrir, I am open to any ideas, especially when it come to wiring problems. I have looked everywhere for a wiring diagram that would fit this engine setup, so if anyone has one handy it would help. It is carbureted 4bbl Holley elect choke, 5.7 Vortec with Delco EST.

 

[Fun Times]

Re: Ignition problem on 5.7

With the key on engine off, try wiggling the main wire harness on the engine to see if you get a change.

Do you have the 10 pin black cannon plug or a 14 pin connector kind of like this, http://www.boatersplus.com/images/detailed/117/710-84-866337T01.jpg

Also do you have the Mercruiser turn key start carburetor?

 

[thumpar]

Re: Ignition problem on 5.7

Did it work correctly before the rebuild or is this all new to you?

 

[achris]

Re: Ignition problem on 5.7

Seems the fuel gauge and the oil pressure gauge are linked with the problem. Without seeing how they are wired it's very difficult for anyone other than you to see how it's done. But, a starting point would be to disconnect the fuel and the oil pressure gauges and see if anything changes...

Short of drawing your own diagram, you won't find one... The Delco was never a part of OEM, so there would be no diagrams for it.

Chris.....

 

[magic11305]

Re: Ignition problem on 5.7

I have the 10 pin plug, I am not sure what a turn key start carb is. It has a regular ignition switch on the dash, heated choke on the carb. This boat was a project I bought cheap, pulled the engine and did a total rebuild with replacing all electrical components. It appears that just about everything that was done by the po, was half a**ed. Can't emagine how the po even was able to operate it. I have been researching all evening and I came upon an idea......I replaced the alternator and the instructions said to hook up a 12 volt source to the exciter, I think I just jumped from the 12v post on the alternator which would give it power anytime the battery switch is on, maybe thinking it should be on a switched wire?

 

[achris]

Re: Ignition problem on 5.7

I have the 10 pin plug, I am not sure what a turn key start carb is. It has a regular ignition switch on the dash, heated choke on the carb. This boat was a project I bought cheap, pulled the engine and did a total rebuild with replacing all electrical components. It appears that just about everything that was done by the po, was half a**ed. Can't emagine how the po even was able to operate it. I have been researching all evening and I came upon an idea......I replaced the alternator and the instructions said to hook up a 12 volt source to the exciter, I think I just jumped from the 12v post on the alternator which would give it power anytime the battery switch is on, maybe thinking it should be on a switched wire?

That would do it. Take that wire off the excite post of the alternator and run a wire from the electric choke to the excite post....

Your gauges may be a different wiring problem... :facepalm:

 

[magic11305]

Re: Ignition problem on 5.7

Chris, I did unplug the oil pressure sending unit while the engine was running and the gauge went dead, when I plugged it back in the guage read 38psi.....gotta love wiring problems. I have not messed around with fuel guage yet, I started thinking they were all connected to my problem some way. Also, when I unpluged the oil pressure sending unit, I expected the fuel pump to shut off, but it didn't? Trying to give as much info as I can think of.

 

[magic11305]

Re: Ignition problem on 5.7

Looking over my rebuild notes, yea sad ain't it , I recall the electric fuel pump getting power from the choke wire? Not my doing.

 

[dan t.]

Re: Ignition problem on 5.7

The exiter wire on a delco alternator (switched ignition) need 1 of 3 things inline to prevent feedback
1 a lightbulb (idiot light)
2 a diode
3 a resistor
Back in the stock car racing days we would always run an idiot light as well as a volt meter, twice it saved an overheat when we lost a fan belt.

 

[magic11305]

Re: Ignition problem on 5.7

If I unplug the switched wire (purple), the engine runs fine, the volt meter says its charging, and I can shut it off with the ignition switch like it is supposed to. With that purple wire connected, all the same except the engine does not shut down. Putting an idiot light in line will take care of this? If so, what size or kind and where could I splice it in where it would work? I stopped in radio shack today to check on diode or resistor, I may as well have been speaking Chinese. They could not tell me wich way or where to install any off it. They said if I know what I want, they will show me which shelf it is on. You would think that a person would have to have some sort of knowledge to work in a store like that....... Anyways, I would love any help . Thanks

 

[magic11305]

Re: Ignition problem on 5.7

Fixed the engine shut down problem, 1amp diode on the purple exciter wire. Works as it should now. I am now trying to track down my fuel guage problem, going to do some tests tomorrow. Thanks everyone for the input.