Starting Problem 1990 4.3L OMC

[xdgt03]

Hello

Newbie here but not to forums. And a newbie boat owner. I am pretty familiar with engines and electrical systems on cars but boats are somewhat different with some additional components.

I have done a lot of searching and found somethings that are helpful in diagnosing my problem but none seem exactly the same so maybe someone here has and easy answer.

I have downloaded and reviewed the repair manual too. Thanks to Don S for all that good info.

Here is my problem. I have a 1990 Four Winns 180 with a 4.3L (I believe it is not HO) It will start with the key engaging the starter but it dies within 1 second after releasing the key. If I keep the starter engaged the engine runs and revs but a second after I let the key go it stops.

I checked the fuel pump and it is working fine. There is fuel at the carb.

I checked what I can see of the wires and all appear in good shape. I checked for voltage at the coil with the key in the on position and there is no voltage. I believe there should be voltage at the coil with the key in the on position, correct?

I know the points are very worn but not corroded. Would it even start at all if the points were the problem?

Is there a common problem here that I am not aware of? Might it be a neutral safety problem? I read about some assist solenoid. I traced a white and gray wire from the the poles of the coil to a harness where they change to black and blue and go into some pack mounted to the side of the throttle bracket. What is this. Could that be bad? Is there a test for whatever that is?

Any help you guys can provide would be greatly appreciated.

Thanks much, Scott

 

[a70eliminator]

Re: Starting Problem 1990 4.3L OMC

Could be the ignition switch itself worn out, when key is in the run position the circuit is not being made, no volts to coil, but then there is that resistor wire that could be faulty too, I hate electrical symptoms. Someone else could probable help you out better than I.

 

[nola mike]

Re: Starting Problem 1990 4.3L OMC

Hello


I checked what I can see of the wires and all appear in good shape. I checked for voltage at the coil with the key in the on position and there is no voltage. I believe there should be voltage at the coil with the key in the on position, correct?



Thanks much, Scott

yup, that's your problem. there's a bypass to the coil with the key in the "start" position, which is why it will start but not keep running. in the "run" position you're on a different circuit. should have ~5 or so volts to the coil with the key in "run" position, going through resistance wire back to choke, and then back to the ignition via the purple wire.

EDIT: whoops, didn't see we were dealing with an OMC. likely same principal though.

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

What is the component that I should be looking at? The ignition switch is okay I think because the fuel pump is wired to the same pole on the switch as what goes to the starting system so there is power going through the switch. (That was rewired by someone and may not be exactly where the pump is supposed to be wired).

It also has a vacuum choke not electric. I read a lot about the electric chokes here but there is no wire running to mine, just a vacuum tube.

Thanks for the info

 

[airdvr1227]

Re: Starting Problem 1990 4.3L OMC

Ignition switch

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

Ok, after further reading and looking over the schematics I think I have a bit more info.

Ignition switch

If the ignition switch were bad wouldn't it also be bad for the other things (like the fuel pump) which are wired to the same pole on the switch? There is 12volts leaving that switch on the run pole.

The E.S.A modual is in that ignition circuit but does that affect it starting or interupt voltage from going to the coil when not started but in the ignition switch in the run position?

The manual does not specify the 4.3L in the ignition wiring schematics but I think it is basically the same as all the other motors except that I have OE white wires as well as gray and black wires running to my coil. I don't see anything in that circuit that could obviously be the problem unless I am missing or don't understand something.

 

[PBJMAN]

Re: Starting Problem 1990 4.3L OMC

Hi, to original poster. We may have a similar issue. I don't have an answer yet but if I get one in my thread (see: starting problem after changing starter) then I will post here for your info, too.

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

Awesome. thanks. It appears that the starter is somehow involved in the ignition system but I'm not clear exactly how. I won't be home until after 4pm so I have some more checking and testing I'm gonna do. If I run across an answer I'll be sure to let you know too.

 

[PBJMAN]

Re: Starting Problem 1990 4.3L OMC

Hi, to original poster. We may have a similar issue. I don't have an answer yet but if I get one in my thread (see: starting problem after changing starter) then I will post here for your info, too.

It's me again. My problem was a loose tether. Duh on me!

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

Checked the coil. Good
Checked the ignition switch. Good
Removed all wires from coil and turned key to run. No voltage to wires that connect to coil.

Started raining so that is as far as I got last night.

 

[PBJMAN]

Re: Starting Problem 1990 4.3L OMC

Can you be more descriptive of your symptoms? When you turn the key on, do your dash lights come on? What accessories are working (gas guage, horn, bilge, blower, nav lights, etc)? When I turned my key I could start but if I let the key go, it wouldn't run. I had no horn, dash lights, or gas guage with the key in run position. As soon as I checked the tether, the dash lights came on and I was pretty sure I found my problem. Sometimes the tether can appear to be on but still be too loose. I even knew of one guy who never used his tether, but one day discovered the cap was cracked and there was a jumper wire that had come loose and caused his starting problem.
If you have checked your tether, then maybe this can still be helpful to someone else.

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

Sounds the same as for the starting. I don't know about the lights. The dash is kinda beat up and because it doesn't run I don't know what ones work and what doesn't. This kind of a fixer upper. It has low hours but was not covered very well and stored outside the last few years. It was winterized tho and it did run but it has not been on the water since I bought it a week ago.

Today, I'll be checking the safety switch if it isn't raining. If that isn't it I'll be working forward from there to see where the voltage stops.

 

[xdgt03]

Re: Starting Problem 1990 4.3L OMC

Now running. I checked several more things and traced it back to a bad safety switch. Spliced the wires together and the engine starts and runs great.

It brings to mind the old adage "When you hear the sound of apporaching hooves think horses not zebras." It's usually the simple thing not the more complex.