1997 Mercruiser 5.7l w/ 2 barrel carb & thunderbolt ignition

jaxbch

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Joined
May 17, 2022
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1
Hello, I’m new to this forum; I just purchased a 1997 Bayliner Capri 2050 which ran like a top in the seller’s driveway, however as soon as I got it home it gave me some trouble when trying to start engine, but it finally started and ran a bit rough. The next day it would not start, it acted like it was about to start but just couldn’t get there, and there was a fairly strong smell of gasoline. After checking spark and fuel, neither of which showed complete failure…I actuated the accelerator pump and fuel jetted out just as it should; I then checked for spark and there was spark, which seemed a little weak. Due to the weak spark I replaced the distributor cap, rotor, and ignition sensor with new Quicksilver brand components. After a few tries and babying the throttle it fired-up and ran pretty well. Two days later I could not start it; fast forward 4 days and after trying for 10 minutes or so I got it started with a lot of black smoke and a couple backfires. That was five days ago and I’ve yet to be able to get it started again…the strong smell of gasoline was present. I have ordered a remanufactured carburetor which should be delivered in a couple weeks. The thing is I’m wondering if the Ignition Control Module could be bad or going bad intermittently. That particular part is well over $500 and I can’t afford to keep replacing components until the problem is solved. One other possibility is the low-oil pressure / high water temperature warning system that is malfunctioning. The previous owner/owners attempted to correct a malfunction oil-pressure gauge which still does not work. There are a couple wires back in the engine compartment which aren’t connected to any terminal. If anyone has an idea or two I would be so grateful for any input. Also, I’m looking for a wiring diagram specific to the exact year and configuration of my boat, as well as a photo showing electrical connections as the we’re before my predecessors started screwing with them. I thank you guys in advance for any advice you have.
 

alldodge

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Staff member
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Mar 8, 2009
Messages
42,884
Could use the serial number of your motor?

Most of your issues sounds like a flooding carb which needs rebuilt, but looks like your replacing.

Pull the plugs, inspect them and do a compression test. If the motor has low compression then it will be hard to start. Need to check timing

Being a new to you boat there should be many things to do. Replace impeller and drive lube. Check drive alignment
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,528
Carb or EFI? What's your starting procedure, and if carb'd are you familiar with how to start a carb engine?
 

Rick Stephens

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Aug 13, 2013
Messages
6,118
I seriously doubt an ignition module. They are 'solid state' and tend to either work or fail, not be intermittent.

New to you boat, as AD mentioned, needs bow to stern maintenance gone through completely. If I was to do a partial list of suggestions, something like:

1)Get a Mercruiser OEM Service Manual
2)Compression test
3)Pull outdrive and service/inspect
* impeller
*u-joints
*gimbal bearing
*prop splines
*lube oil change
4)bilge blower works and learn to use religiously
5)bilge pump works
6)hydraulic pump oil is not full of water


Something like that is a good start.

Rick
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,528
I seriously doubt an ignition module. They are 'solid state' and tend to either work or fail, not be intermittent.

New to you boat, as AD mentioned, needs bow to stern maintenance gone through completely. If I was to do a partial list of suggestions, something like:

1)Get a Mercruiser OEM Service Manual
2)Compression test
3)Pull outdrive and service/inspect
* impeller
*u-joints
*gimbal bearing
*prop splines
*lube oil change
4)bilge blower works and learn to use religiously
5)bilge pump works
6)hydraulic pump oil is not full of water


Something like that is a good start.

Rick
I feel like there was a "new to you boat checklist" floating around in a sticky somewhere, but I can't find it. If not, it should definitely exist
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,589
I feel like there was a "new to you boat checklist" floating around in a sticky somewhere, but I can't find it. If not, it should definitely exist
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,528
Yeah, knew about that one. We need a, "Well, you didn't read that last sticky and already bought the boat, now what?" thread.
 
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