Boat won't start... questions within/

[AdamB]

I have a 1985 Mercruiser 350 that used to have a Thunderbolt IV igntion system. I just converted to multi port fuel injection that uses a GM EEC from a 1990 corvette. Anyhow, after installation, ran fine than started to run rough. Now, won't start at all, wants to catch, but just doesn't.

I was checking the coil, has power at both + and - terminals when switch is on. Both are same reading, around 12.5 volts's, is this normal? It has around 3.2 ohms with no wires attached. Haven't done a spark test to see if it's actually sparking...yet.

 

[AdamB]

Re: Boat won't start... questions within/

Okay, did a generic spark test (hooked wire to spark plug at placed against metal), the spark was sparking, although not very bright. THe engine is trying to catch, but just doesn't all the way. I do smell fuel, so ???????

I guess tomorrow I'll get some starting fluid, and a new coil just to check.

The timing was set to 6 BTDC, but now I've adjusted it is slow increments to see if the motor will start. I can tell if I go too far because it won't even attempt to start.

 

[calwldlif]

Re: Boat won't start... questions within/

Kewl upgrade, I might pick your
brain.
You must have some skills, you did upgrade.
Hows the voltage to the coil?
How long did it work properly before
this trouble?
Smell gas? how are you regulating the mixture
MAP,MAF
Did you have the ECM reflashed?

 

[Don S]

Re: Boat won't start... questions within/

A Corvette also used an oxygen sensor, something not used on boats because water is in the exhaust.
I also wonder how you got that automotive EFI system Coast Guard certified for fire and explosion protection like all the other marine systems have to do.

 

[AdamB]

Re: Boat won't start... questions within/

Well, the EEC had the VSS and oxygen sensors programmed out the by fuel injection company where I purchased the unit. It did run (well idle anyway) good, but the regulator was leaking fuel, and the company sent me a new one. I never really got a chance to WOT it as I had to take apart the fuel rails and reinstall the regulator. I have an electronic fuel pressure sending unit which is showing the pressure from almost negative all the way up to 60 psi so I know the adjustable reg is working. I think I can smell fuel, so I'm assuming the injectors are injecting fuel. There is only 2 trouble codes showing up, 12 and 42. 12 is normal, and 42 is because I had unhooked the 1 wire on distributor when I timed it, also normal. I installed and the motor only ran for approx. 10 minutes and doesn't start. I don't know if it is fuel or ignition related, there is small spark so I'm guessing it is fuel...

I would like to see a Coast Guard type inspect my vehicle and actually realize what it is under the flame arrestor. The electronic fuel pump is within 12" of motor, and all fuel lines are CG approved. I'll pass on setting my boat on fire and seeing how long before it explodes................8)

Anyhow, back to the coil, is it supposed to have the exact same volts across the coil terminals. I have a basic (maybe) understanding of how coils work, with 12v side and secondary side, but not sure I'm getting enough spark. I'm thinking of just unhooking the factory 12v side of the coil and running a jumper 12v lead to + side of coil from battery just to elimate faulty wiring somewhere.

I verified the shift cut out is working, as it grounds the coil when activated.

The system is MAP controlled. I don't feel or hear any vacuum leaks but that is a possibility.

I'll use some starter fluid down the throttle body, run the battery jump to the coil and see if I can get it to start tomorrow. If it starts, I guess the ECU isn't injecting fuel right. Was just trying to avoid having to buy new coil since I just bought this one like 2 seasons ago.

 

[Don S]

Re: Boat won't start... questions within/

I would like to see a Coast Guard type inspect my vehicle and actually realize what it is under the flame arrestor. The electronic fuel pump is within 12" of motor, and all fuel lines are CG approved. I'll pass on setting my boat on fire and seeing how long before it explodes................

It's no "All About You" fella, there are other boats in the area, and those unlucky enough to know don't know what you are doing and that everything on your engine isn't autherized as safe on your boat. And yes, it more than just CG approved fuel lines.

I'll use some starter fluid down the throttle body, run the battery jump to the coil and see if I can get it to start tomorrow.

Starting fluid ! ! ! ! !
You really don't know much about gas engines do you?

 

[AdamB]

Re: Boat won't start... questions within/

Don S, I didn't mean to get on the wrong side of you for sure. I've installed something that was marketed as marine safe, uses GM equipment (just like on the mercruisers). Sorta like some kid putting a louder aftermarket kit on his car.,.. well maybe not like that.

Anyhow, I've worked on lots of cars, a 520+ hp Ford 302 Supercharged H/C/I engine running 11 psi boost. Runs and operates as it should (although it runs on roads). This was supposed to be a simple manifold change, distributor change, get rid of the Thunderbolt and exhange with EEC from GM. Started and idled great but now??????????????????

Now, back to the boat. I hooked it up before, but short of regulator leaking fuel, it ran. NOw, I get new regulator, get it all back together is some serious heat and it only ran for 10 minutes. I noticed the oil is coming out of the coil and then I find I can screw the coil screw (from high powder or sec side) in lots... just wondering if my coil is messed up is all I was after with this thread.

 

[AdamB]

Re: Boat won't start... questions within/

Just caught this cute comment... well, I've torn some apart and understand the fundementals of air, spark, gas, etc. and have always have done my own engine work. I'm not a mechanic though, so that's why I am here. If I'm not geting enough gas, and I spray a little bit of ether in there, she'll fire up. Then I would know I wasn't getting enough fuel...........no? I already verified I'm getting some spark, although not sure if enough to fire a very rich engine if that is what my problem is. Or do I have a very lean engine. Fuel psi is set to 40 w/o vacuum line... engine just stumbles but never starts. Sounds ignition related....

I would answer my own question about the coil with another vehicle, but nothing I drive has a coil setup like this. But, I don't think the coil is supposed to bleed voltage right through the terminals without some loss right? I know a coil gets a voltage across it's terminals, then as the volts bleed off, the high current is produced on the high voltage side.... something to do about magnetic fields etc. So, if I ground 1 lead on engine block, and test other lead on coil and get 12volts, then check the other terminal on coil, should I get the same 12volts?


Starting fluid ! ! ! ! !
You really don't know much about gas engines do you?
[/quote]

 

[RubberFrog]

Re: Boat won't start... questions within/

... I noticed the oil is coming out of the coil ....

Sounds like that is a good place to start.

 

[AdamB]

Re: Boat won't start... questions within/

I just ordered a new high vibration epoxy filled MSD coil. I also ordered the MSD 6M marine ignition box, supposed to help by sparking twice etc. I'll report back if replacing the coil fixes my issue. I already verified the injectors ohm propertly about 16 ohms each, there is voltage at the injector wires, and the spark plugs are black and smell of gas. Hope it is the coil............

 

[b00tstrap]

Re: Boat won't start... questions within/

If you have the repair manual, you may be able to find a resistance test for the coil (both primary and secondary windings).

Ignition coil theory - Your ignition coil is a big step up transformer. 12volts input .. a few thousand output. One side of the coil is wired to 12v (ignition switched) and the other goes through your points (or electronic equivilents) to ground. When the points close, the 12volts appears across the primary windings of the coil and electromagneticly transfers to the secondary windings providing a high voltyage output to the distributor, which is then distributed to the correct spark plug based on the distributor positon.

To test a coil, start by dissconnecting all wires (you will want to do this test at a bench rather than near any flammable substances like gas. Connect a plug wire that (normally goes to the distributor) onto a spark plug. Strip the end of some jumper wire and wrap it around the threads of the spark plug and put the other end to a good ground source like a battery (-) terminal. Then connect another jumper wire to the positive terminal of the coil to the (+) side of the battery. Lastly, take a third jumper wire and connect it to the (-) side of the coil.

To perform the test, tap the third jumper to ground, when you do a bright blue spark should appear across the spark plug (so don't hold it!). The spark should easily jump a 1/4" and should be nice and fat!

When the engine isn't running (the points are not closed) you WILL measure approximately 12V on both the (+) and (-) side of the coil. What you are seeing is the voltage "bleeding" through from the 12v (+) side to the (-) side of the coil where it is waiting to be grounded. The voltage drop across the coil should be minimal, anything more than a volt or two difference between the (+) and (-) side could mean the coil is bad.

 

[AdamB]

Re: Boat won't start... questions within/

Thank you for the explanation.
Too late though, I ordered the new epoxy filled coil and msd 6M ignition box to go along. Hopefully now it;ll work.

If you have the repair manual, you may be able to find a resistance test for the coil (both primary and secondary windings).

Ignition coil theory - Your ignition coil is a big step up transformer. 12volts input .. a few thousand output. One side of the coil is wired to 12v (ignition switched) and the other goes through your points (or electronic equivilents) to ground. When the points close, the 12volts appears across the primary windings of the coil and electromagneticly transfers to the secondary windings providing a high voltyage output to the distributor, which is then distributed to the correct spark plug based on the distributor positon.

To test a coil, start by dissconnecting all wires (you will want to do this test at a bench rather than near any flammable substances like gas. Connect a plug wire that (normally goes to the distributor) onto a spark plug. Strip the end of some jumper wire and wrap it around the threads of the spark plug and put the other end to a good ground source like a battery (-) terminal. Then connect another jumper wire to the positive terminal of the coil to the (+) side of the battery. Lastly, take a third jumper wire and connect it to the (-) side of the coil.

To perform the test, tap the third jumper to ground, when you do a bright blue spark should appear across the spark plug (so don't hold it!). The spark should easily jump a 1/4" and should be nice and fat!

When the engine isn't running (the points are not closed) you WILL measure approximately 12V on both the (+) and (-) side of the coil. What you are seeing is the voltage "bleeding" through from the 12v (+) side to the (-) side of the coil where it is waiting to be grounded. The voltage drop across the coil should be minimal, anything more than a volt or two difference between the (+) and (-) side could mean the coil is bad.

 

[bruceb58]

Re: Boat won't start... questions within/

The explanation isn't quite correct.

Grounding the - side of the coil flows current through the coil. When the ground is removed, the magnetic field in the secondary windings collapses which causes the spark.

When the points are not closed you will see 12V at both sides of the coil because there is no current flowing through the coil.

 

[b00tstrap]

Re: Boat won't start... questions within/

bruceb58

I'm glad you felt the need to clarify. I try to stay away from explanations that focus too much on technical accuracy rather than a clear conceptual of the workings. There are plenty of resources that will discuss the theory of electronics if you need that level of detail.

 

[AdamB]

Re: Boat won't start... questions within/

well, I appreciate the above info from all. I hooked up my new MSD coil and 6M (marine CG approved) ignition, and the engine fired up. I had previously removed a plug and found it to be completely fouled, extremely black and wet. Apparently the factory coil crapped out and my atempting to continually start the engine flooded it something fierce. While waiting for Summit to ship my new coil, I checked the plugs and they were fouled big time

The MSD managed to fire the engine even with the fouled plugs. I think I will sear by MSD now in my boat. The injectors must have dumped too much fuel in and the plugs fouled. Now, everything is good.

I didn't have points, I had an electric ignition (Thunderbolt IV) before, and converted to a HEI GM with electronic ingnition. Used a magnetic pickup to drive the coil. Anyhow, even though my old coil ohmed out right, it wasn't firing. It was leaking oil and I think something must have vibrated loose on the high voltage side and messed up the coil (the screw that is below the distributor lead was way loose and thats why the oil was leaking). I tightened it, but must have messed it up.

Anyhow, now I got major multiple sparkage 8) and it's even marine approved. The magnetic pickup from the distributor now goes to the 6M ignition, and it has a + and a - wire that goes to the coil. The 6M is a capacitor ignition, and keeps the coil fired up at all times (or something like that) Anyhow, it works. Thanks for all your help.

 

[AdamB]

Re: Boat won't start... questions within/

Oh, I just re-read the above and still can't figure why my coil wasn't firing. I had 12 volts on both the neg and pos, it ohmed out right.... don't know. Maybe I should have changed the plugs before buying the new coil, but what caused my plugs to foul in the first place? I now have very easy starts. I opened the gap on my new plugs alittle, since my new coil and 6M supposedly make up to 45K volts... seems to work.