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View Full Version : Coil for Carbed PCM 351s with electronic ignitions....


03geetee
05-31-2011, 02:20 PM
Guys,

What coil have you had success with on your boats with this setup. The past owner bypassed the resistor box and ran an unresisted coil which ultimately destroyed the coil this weekend. Running another coil that is internally resisted but I dont have any idea the background since it was used from my local marina.

My boat is suffering from the following...

-Terrible non existent hot starts, run it for more then 5-10mins and shut her off she wont restart.
-choke flap is closing when I dont want it to on morning starts, seems to start just fine when I remove the flame arrestor and hold the flap open.
-no flooding whatsoever, checked the plugs every time and were dry.
-the carb is squirting fuel into the primarys when I pump the throttle, normally 2-3pumps will do it and she fires right up when cold.

Timing is 10 BTDC, plugs are autolite 24s gapped to .034, electronic ignition, operating coil, carb is recent within 2-3years old. Starter is original and loud as hell which I think is my most glaring problem. Going with an Arco unit soon. Battery cables and terminals from battery to soloniod newer, and so is the ground to the starter from solenoid.

What am I missing here, I am paranoid this boat might stall in the middle of the lake and I wont be able to start her.

I have researched alot of threads on this topic but wanted to see if there was anything I was missing.

Thank you.

JTR

cbryan70
05-31-2011, 02:32 PM
When it wont start after running it have you tried taking the flame arrestor off and closing the flap?

03geetee
05-31-2011, 02:41 PM
When it wont start after running it have you tried taking the flame arrestor off and closing the flap?

No only the opposite, halfway closed or more and nothing happens, but as soon as I opened it up full I would get life.

Also note all fuel lines from tank to motor have been replaced in the past 2 years, new fuel filter, new fuel pump ect. Just seems like a gremlin I cant shake but this one has to go.

JTR

cbryan70
05-31-2011, 02:43 PM
Ahh I read that the choke flap was closing on morning/cold starts?

So in a hot start you open the flap all the way and it will fire off?

03geetee
05-31-2011, 02:48 PM
Ahh I read that the choke flap was closing on morning/cold starts?

So in a hot start you open the flap all the way and it will fire off?

Yes sir!

Think my starter is spinning the motor too slow to generate enough airflow with the flap slightly closed? Just a hunch.

JTR

johnlanguab
05-31-2011, 02:48 PM
Previous owner had the same problem with my boat. He had just picked up a coil from the auto parts store, and after running it a while it would get really hot and the boat would barely start, if at all. I recommend checking with www.skidim.com. I know they have the correct coil.

cbryan70
05-31-2011, 02:53 PM
Yes sir!

Think my starter is spinning the motor too slow to generate enough airflow with the flap slightly closed? Just a hunch.

JTR
??? Odd that your boat is opposite mine. I have a 78 with the 351 and when it does not want to start Hot I close the flap all the way and it fires right up.

WilliM1940
05-31-2011, 04:31 PM
You would benefit from a more modern gear reduction permanent magnet type starter. They are smaller, easier to cool and draw less amps when starting. Skidim has them. My theory is the engine was made to install in a car, where air blows around the starter motor and helps to cool it in between starts. In the boat, it just soaks heat when shut down in the bilge, increasing the amp draw. Your choke is electric, run by an electrically heated coil to operate the choke plate. Kind of divorced from what the engine really needs. You can try to key on and wait for the choke plate to open before engaging the starter. I am thinking about going manual.

Table Rocker
06-01-2011, 10:13 AM
On most carbs you can adjust how much choke you have by loosening the retaining screws and rotating the choke cap.

https://www.speedwaymotors.com/images/PDF/42745223.pdf

Hollywood
06-01-2011, 10:21 AM
-Terrible non existent hot starts, run it for more then 5-10mins and shut her off she wont restart.

Assuming you have the choke figured out, this could be another coil problem. Is it oil filled and laying on its side?

03geetee
06-01-2011, 01:19 PM
On most carbs you can adjust how much choke you have by loosening the retaining screws and rotating the choke cap.

https://www.speedwaymotors.com/images/PDF/42745223.pdf

Will look into this...thank you.

Assuming you have the choke figured out, this could be another coil problem. Is it oil filled and laying on its side?

Not sure but worth looking into, yes the coil is mounted in the intake parallel to it. I am somewhat leaning toward this as well, but not sure.

JTR

wheelerd
06-02-2011, 02:05 AM
I used an Accel Super Stock coil on my 91 that had been upgraded to electronic ignition. It put out about 42,000v. Old coils are susceptible to heat degradation.

BrianM
06-02-2011, 07:57 AM
You do not want to run any resistor with the electronic ignition. Petronix ignitors need full voltage. Stock coils work fine with them or you can run one of the aftermarket hotter coils. The other thing is the electronic ignitor my be going bad. I had one in my '88 and had similar symptoms with a brand new one. After chasing ghosts I sent the unit back and replaced with new and the boat ran like a champ.

MrMan
06-02-2011, 06:40 PM
was hoping to find this thread helpful but I seem to have other issues.

Was planning on firing up boat for the 1st time this season and got no fire; just cranked and cranked. Bought new coil, spark plugs (.035), distrib cap and rotor, points (.019 gap) and condensor AND new battery but still not starting.

Carb IS fueling when I mash it, and occasionally it TRIES to hit a lick but won't.

1990 TriStar 190 351 Ford

I realize electronic ignition is the way to go but that won't get me on the lake tomorrow.

-Bummed in Nashville

03geetee
06-02-2011, 06:47 PM
Measure voltage at positive terminal with the key on to make sure the power is reaching the coil. If not a new coil is no better then the old one.

Have you determined whether or not you are getting spark by hitting it and tossing some starter fluid inside to see if it kicks? If it doesnt you are getting no spark at all.

JTR

MrMan
06-02-2011, 09:03 PM
I have tried starting fluid and still not hitting. I have a plug wire and plug laying against motor and it does not spark when cranking.

I haven't checked voltage at the coil yet.

What baffles me as much as anything is that the boat ran fine when I shut it down and winterized in Novemeber.

03geetee
06-02-2011, 09:12 PM
I have tried starting fluid and still not hitting. I have a plug wire and plug laying against motor and it does not spark when cranking.

I haven't checked voltage at the coil yet.

What baffles me as much as anything is that the boat ran fine when I shut it down and winterized in Novemeber.

Mine ran the night before like a top. Trailered it up to WI for 3.5 hrs went to start it the next morning with no other changes and it wouldnt do a thing.

I would get a reading at the coil positive side, if you have 11-12vs there then your coil is most likely not sending anything to your distributor. The second I changed the coil within 1 revolution of the starter my motor fired from all the starting fluid I suppose.

Worth a shot bro!

JTR

BrianM
06-02-2011, 09:13 PM
Double check your safety lanyard. My have come loose during winterization or fatigued over storage and not holding switch properly.

MrMan
06-02-2011, 10:16 PM
I checked the lanyard today; when I pulled it and cranked, all gauges went dead, so I think I'm good there.

Can't find my volt meter but did get a bit shocked earlier when I was rechecking points gap and accidentally left the key on. Seems to be some power there.

On the old coil, 1 post had "bat" next to it (1 wire), the other had nothing stamped (2 wires). The new coil has "+" next to 1 and "-" next to the other. I have the 1 battery wire on the "+" and the 2 wires on the "-".

Do you set the points when the contact is on the "bump" or when it is on the flat part of the distributor? I set my gap when point was on the "bump". I set at .019. An old mechanic told me to do that. I have read everywhere from .018 to .025.

liledgy
06-02-2011, 11:00 PM
Would a broken spring in the distributor below the points prevent the boat from firing?

WilliM1940
06-03-2011, 12:50 AM
Mrman, this may or may not be your problem, just relating some experience. The point gap is a rough estimation of what you are really after which is point dwell. This can be read from a dwell meter after the point gap is set, and I believe usually you are looking for 24-32 degrees. In my case the point gap is only .014 to achieve this. Secondly, it is possible to short the points out (in this crummy setup) with the leaf spring on the points assembly if they are assembled wrong. Nothing should touch the metallic parts of the points arm, even slightly.

MrMan
06-03-2011, 09:27 AM
just pulled that "plate" from distributor and the 2 springs are fine. Thanks for the input!

MrMan
06-03-2011, 09:31 AM
Will, something doesn't look quite right with the points; not EXACTLY identical. I am taking them back to see what's up. Also, that flap was EXTREMELY close to the screw that holds them down.

Thanks!

wheelerd
06-03-2011, 10:05 AM
Obviously your primary circuit (ie. starter) is getting power. So it's somewhere in the secondary. If you are getting juice INTO the coil, then the problem has to be somewhere between that and the plugs:
- loose or shorted wiring
- a breaker or fuse blown
- internal short in coil and/or ballast resistor
- internal short in distributor
- distributor was accidentally moved changing the timing
- distributor rotor shorting or removed (ya, that got me once!)
- distributor cap cracked and/or shorting
- spark plug wires and plugs (although it's unlikely that all 8 would be bad at the same time)

MrMan
06-03-2011, 12:13 PM
I took the points back, re-installed new points and made sure there is no short. plugs are firing; I took them out 1 by 1 and made sure ALL had fire.

still won't start up.

SURELY, it has to be flooded due to 2 days of cranking.

I DID get a backfire during 1 of the plug tests. starting fluid pop maybe?

definitely has me scratching my head. 90 degrees at 11am and I'm in the driveway; man, that sucks!

03geetee
06-03-2011, 12:25 PM
Other then the motor being completely timed wrong, or firing order with a new coil, starting fluid and a rotating motor you should get something.

Let me think some more...


JTR

WilliM1940
06-03-2011, 12:40 PM
I would recheck your firing order and timing, a couple misplaced spark plug wires could do it. Other than that with fire and fuel, about the only other unlikely thing that could screw you is a timing chain that jumped a tooth.

MrMan
06-03-2011, 01:15 PM
I had the wires "1-off" on the distributor.

fired right up.

crazy.

I REALLY appreciate ALL of the input and advice; you guys are GREAT!

me and the kids are headed out to the lake to give her a nice run.

Yesterday was the first time she left me standing in the driveway since i bought her in 1998(other than tranny going out in 1999; she still limped back to the trailer) and as it turns out; it was my fault all along!

Thanks again!
Charles- Hermitage, TN

03geetee
06-03-2011, 07:30 PM
High five!!!!

JTR

wheelerd
06-03-2011, 08:45 PM
I had the wires "1-off" on the distributor.

fired right up.



Ah!!! You never told us you had removed the plug wires at the distributor. :D:D
But glad it's all sorted out now.

MrMan
06-04-2011, 11:51 PM
yeah, my old distributor cap had a "1" printed on it, off center on the the 1 wire; the new cap had nothing. I put wires on the wrong side of that "off center".

to be honest, the way I did it at first "looked" right, looking down on it, but I thought I'd change them just for $h*t's and giggles and to be sure.

But thanks!