1983 3.0 hard start

[airshot]

I have a 1983 3.0 with a elec ign conversion, motor runs excellent if you can get it started. Had some issues at end of last season and with I-boats help thought I had it solved, but as this season is starting we have the same issue. First off, compression is good, all new wires, plugs, cap, rotor and new coil. Usually when warm will start backup unless it sits for a while, then difficult starting developes. Now here is something I discovered...if I jump a 12v hot wire from batt to plus side of coil it will start right away!! That tells me the coil may not be getting a full 12v on initial startup but where do I look? Ign switch, wiring to and from switch or should i be looking elsewhere? Thanks in advance for your help.......

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[dubs283]

Re: 1983 3.0 hard start

when you converted to electronic ignition did the instructions say to use the same resistor wire for the conventional ignition or to run a new non-resisted (12 volt) wire to the (+) side of the coil??

 

[airshot]

Re: 1983 3.0 hard start

Thanks for responding, I did not do the conversion the previous owner did, however what paperwork that I have as well as being marked on the unit itself it states no external resistor/wire is required.
Here is what we have found so far...checked all connections, used a light for testing as this was quicker, checked brightness at 12 v, then hooked it to pos coil side, when you turn engine over the light gets dim, engine hard to start. If I jump a hot wire from batt to + coil, light stays bright while engine cranking and engine starts right away. We have traced wires back and forth from diagram and all seems to be ok. had this issue last year, thought it was a bad coil but since replaced that. One thing we did find as an experiment if we disconnected the pickup in the dist, the light on the coil stayed bright as the engine turned over. These engines use a slave solenoid in conjunction with the starter solenoid and this type of system is new to me. Any other suggestions will be greatly appreciated.

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[dubs283]

Re: 1983 3.0 hard start

the slave soleniod has nothing to do with the ignition system, unless somewhere along the line there is major resistance causing a voltage drop but if the engine turns over fine i wouldn't worry about that

checking the light at the (+) side of the coil while cranking is going to dim your light because the starter is drawing a lot from the battery

is the coil you installed last year the one for your ignition system?? internally resisted??

you are gonna need to get a volt meter to test a couple things here:

1. check battery voltage - 12 or more volts is what you want

2. check voltage at the (+) side of the coil with the key on engine not running and compare numbers, they should be fairly close

3. if they are not close, like a few volts different, you have found your problem and need to troubleshoot the purple ignition wire circuit

4. if the are the same/fairly close, you may be on the right track with the sensor in the dist being a culprit, you may want to find out as much info as you can on the ignition system you have and either google troubleshooting or get in touch with the manufacturer - otherwise check the connections at the coil for corrosion, etc...

 

[Don S]

Re: 1983 3.0 hard start

When you start the engine cold, do you move the throttle only lever to full throttle and back to idle a time or two, and then raise the throttle to 1/4 throttle to start? Or do you just leave the throttle in neutral at idle to start?

 

[airshot]

Re: 1983 3.0 hard start

First let me reply to dubs...yes the battery is at 12.8 volts (new) and sometimes the voltage reads at 12 plus on the coil and sometimes below, this is where I believe the problem lies. When cranking the engine the light goes from dim to brite I assume each time the ign fires it dims the light, however the light is not as bright as when on 12 volts by itself. If I do get a good 12v reading the engine will fire up, when it is lower than 12 v it just cranks. Is it possible the ign switch is bad not letting full voltage thru intermitently? When I jump the batt to coil the light still dims but no where as much, by staying briter hence more voltage the engine starts up immediately. Again thanks for your suggestions open to any others.

Now to respond to Don, thanks for replying, Yes I do move the throttle but not quit to wide open or I will flood it, about 3/4 way then back to mabey 1/4 throttle. On ocassion it will fire right up, but normally cranks for a while before starting. Coughs and sputters a bit. If I use the jumper wire it will start almost immediately. thanks and open to any and all suggestions.

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[dubs283]

Re: 1983 3.0 hard start

Is it possible the ign switch is bad not letting full voltage thru intermitently?

see step #3 in post #4

 

[tschmidty]

Re: 1983 3.0 hard start

It seems to be pretty clear that you have either the resistor wire still in there or some other culprit. The purple wire is the resistor and is only needed for a points type distributor, electronic should have that wire either replaced or bypassed (or at least any electronic ones I have seen which is not all that many but the principal holds...).

As the above post says, you should be getting full voltage at the coil at all times (with the above assumption). With a resistor wire there is also a bypass wire (purlpe-yellow) from the solenoid to the coil that supplies a full 12 volts (bypassing the reisistor wire) when you are cranking (to give a hotter spark for starting). Maybe this wire is disconnected or there is some weak connection in the solenoid? But in any case shouldn't be necessary since you most likely just need a good 12v to the coil at all times anyway (to be repetitive).

 

[airshot]

Re: 1983 3.0 hard start

Thanks again, the solid purple wire is not there, I assume removed when the elec was replaced.
Only the purple/yellow from the solenoid on the starter to the coil. There is a dull red wire on the + coil to harness, I assume start switch. And the dist wire (brite red) to the + coil. There is a gray (tach) and a black from dist on - on coil. There is a hot wire from the ign switch (added) that goes to the slave sol. as well as red/yellow to slavce from switch. As the boat is near 30 yrs old I am not sure how much has been changed.
My next question is will it hurt anything to leave the hot wire from batt to coil + connected? We did put a switch on it to turn it off after the motor starts, if we leave it connected the ign switch will not shut off the motor, would it be better to leave it on while running? I am going to research this problem however this temp wiring will get us started while we figure out the other problem as long as we are not hurting anything. Thanks again for all the pointers!!
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[dubs283]

Re: 1983 3.0 hard start

you need to check VOLTAGES on each of the wires going to the (+) side of the coil, if you want to solve this problem your test light will not suffiice here

the pur/yel is start assist - it provides voltage to the coil when cranking only, once you let the key bacl to run the voltage goes away

the dull red wire is probably the original resistor wire from the harness for the old ignition

the bright red wire is the new hot wire for the ignition

check voltage with the key on at all wires - you should see good 12 volts on the bright red wire, if the dull red wire is 8-9 volts or less, remove it and cut it back and tape it off, that could be the issue

running a "hot wire" to run the engine is not going to help troubleshooting - its only gonna mask the issue

 

[airshot]

Re: 1983 3.0 hard start

I do have the volt meter and have tested the voltage, sometimes it is good and sometimes it is not, the light was just a quick reference for testing purposes. The problem has been intermitent that has been my difficulty in finding it, however it is becomming more frequent and you have given me some some good direction to look at, many thanks.
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