Engine won't turn over unless hotwired

Jim 5757 · Mar 26, 2016

Go to Universal website. They have a service bulletin on this. Look for the crappy wiring harness plug ( check MainSail's article). Also look for a cheap inline fuse in the wire from start button to solenoid. Got it? Get rid of it!
(Service bulletin #213, 4/13/1994)

centerline · Mar 26, 2016

Either, the wire to the start button has low voltage..... OR, the start button is faulty and not passing the full voltage thru it when pressed.... OR, the wire from to the start button is faulted somewhere.....

And i dont know if you have a booster solenoid/relay in the start circuit to energize the starter solenoid, but if so, it could be faulty.....

You can do all the testing with a volt meter and find it all checks out, but it may still be faulty. you NEED to take the readings when the start button is pressed to find where the voltage is dropping out... so hook up your meter before the connection/switch, and read the meter when while pressing the start button... if the voltage remains constant its all good.... so hook your meter to the starter side of the switch and do the same...... as long as the voltage stays good, keep going down stream in the circuit until you the problem where the voltage drops away significantly.....
When you find that spot where the voltage drops away, the problem will be between where you just checked it, and the last spot you checked to be good...

centerline · Mar 26, 2016

Ok... the small "start" wire at the starter solenoid, what does this read when the button is pressed?... if you.are getting 12v there, then you need to insure the big battery wire to the start soleniod has clean terminals, AND.... the ground wire to the engine block. If the ground isnt good, the circuit is just as faulty as if you dont have any voltage...
Make sure the starter grounds well to the engine block... one would think it should thru the bolts, but i have seen two cases where brand new marine engines had starting problems due to the starters not grounding thru the heavy duty marine engine paint...

Benny17441 · Mar 26, 2016

The harness plugs in to wiring in the control panel and to wiring going to the starter solenoid; it could be this original wiring causing the problem. You have replaced the harness but not likely the ends wiring. Centerline is correct you need to take voltage readings while the circuit is activated when pushing the starter button. The fact that the engine cranks when you jump the solenoid posts leads me to believe that the wiring in the high amp circuit is fine. Like I said check the old wiring and connections in the back of the control panel and check the wires directly connecting to the solenoid. What you describe as best as I can think is due to a voltage drop emanating from the push button circuit.

Skipper · Mar 26, 2016

"Don't touch the 3rd rail. That's 10,000 volts."
"It ain't the volts that'll kill you. It's the amps."
"How many amps are there?"
"Enough to push a train."
-from the 80s movie Running Scared.

The wires might show voltage, and still not carry the current. Go back to check the old wires, and even the new wiring harness if it's the same type. Plus the fuse. It's not the fuse, it's the fuse holder that is the culprit.
Check resistance not voltage.

nlneilson · Mar 27, 2016

Some starter buttons on heavy equipment closes the ground circuit to the solenoid. If when you hotwire it takes just a jumper to a positive wire that would not be the case. Some solenoids on gas engines have an extra lead to bypass the ignition coil resistor. You should have alligator clips on your voltmeter.
If the starter cranks the engine when the solenoid is hotwired the ground to the engine is ok.

Bill Roosa · Mar 27, 2016

Try measuring the voltage with the wires attached to the terminals. ie don't unplug the solenoid and measure the voltage in the wire. There is no current flowing then so you will get battery voltage. If you plug it in and let the device take up a load the current will flow and the voltage will drop.
I suspect the quick connects or starter switch terminals are corroded (99 % of all electrical problems on boats is corrosion).
As a quick fix take apart and reconnect each quick connect in the wiring loom to the starter and re test the starter. do this one at a time to locate the problem child. Also do all the quick connects as it may be a little bit of corrosion on a lot of connections that is causing the problem. Hunters are legend for this problem with no less than 12 connections between the + and - terminals in the starter circuit.

Tom J · Mar 27, 2016

A member of our yacht club with the Catalina 30 had the same issues with his start system, and tried the same fixes. Finally, a technician told him that Catalina had undersized the battery leads to the starter, and he had seen this problem before. The tech exchanged all battery and starter leads for heavier gauge, and solved the problem.
I agree that jumping the start relay and getting a start would indicate a different issue, but just thought I'd mention this possibility.

jssailem · Mar 27, 2016

Increasing the battery lead size will mean less voltage drop. Not a bad idea. Could fit with your symptoms. Maybe MaineSail, Centerline, or Stu will reply to this idea. They are knowledgeable about these issues.

Jim 5757 · Mar 28, 2016

Here's the link to MaineSail's article on correcting Universal starting issues: http://www.pbase.com/mainecruising/universal_wiring_harness_upgrade. It makes some interesting reading!
We had the same problem with our M20! Chased the circuit from one end to the other for weeks; pulled the starter, too! Since we made these mods, we've had no problems...

Do yourself a favor and get rid of that inline fuse... maybe it looks OK, but it's all about voltage drop here. Every tenth of a volt counts and I'll bet that fuse holder assy is dropping 1/2-volt or more. The push button START and GLOW switches are also known issues; especially if they're 25+ years old.
You mention 2-1/2 volt drop across the relay? That can't be good, and if that's certain, you probably have found the problem 'cause the whole idea of the relay is to REDUCE voltage drop! I can't say why a new relay would act that way, but I guarantee it ain't right!
...and just a thought... I wonder if your power plant was originally supplied with a relay in the starter circuit? Is it possible that a PO added that in an attempt to resolve the issue you're seeing now? Anyone else know about this?

Stu Jackson · Apr 9, 2016

OS2Dude said:
Universal M-25 engine

Glad to hear it's "fixed" -- just saw this thread, you might be interested in these:

Critical Upgrades http://c34.org/bbs/index.php/topic,5078.0.html

Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too

[URL]http://www.c34.org/wiki/index.php?title=Diesel_Engine[/URL]

Stu Jackson · Apr 9, 2016

Jim 5757 said:
...and just a thought... I wonder if your power plant was originally supplied with a relay in the starter circuit? Is it possible that a PO added that in an attempt to resolve the issue you're seeing now? Anyone else know about this?

They were not OEM.

Stu Jackson · Apr 9, 2016

Tom J said:
Finally, a technician told him that Catalina had undersized the battery leads to the starter,

Hogwash. My #4 OEMs have been working for 30 years. Even if Maine Sail says they're undersized!

Stu Jackson · Apr 9, 2016

OS2Dude said:
If the relay is not OEM, how should the start button and power be wired to the starter?

The way it shows in the wiring diagram for the Seward panel. It's in the wiki I linked to.

Try this: http://www.c34.org/wiki/index.php?title=Engine_Harness_Upgrade

Engine won't turn over unless hotwired

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SBO Weather and Forecasting Forum Jim & John

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