Mercruiser 3l starter/solinoid problem, stumped

[mckeemm]

Hi All,

Let me start by saying that I have read the tutorials and associated threads and tried all suggestions to date with regard to this problem with no success. Boat is a 2003 Mariah 18' bowrider, low hours.

Problem: intermittent starter cranking. Solenoid throws out (clicks) but starter rotation intermittent.

Background; Starter started acting up at the end of last season and the solenoid finally packed it in during the winterization process. I ordered a new aftermarket marine starter for my installation and installed it late in the fall but since the boat was already in storage I did not have a chance to check it out.

Fast Forward: This spring I pull the boat out to get it ready and the starter will only crank once for every ten tries, then crank for ten starts in a row then work once and not again the rest of the day. It's totally unreliable. The engine starts easy if and when the starter does finally do its job.

So far I have installed a new starter and new battery. I have cleaned all power and ground connections on the battery, engine and starter. Inspected power and ground cables and they are free of corrosion. Checked the slave solenoid as well, no problems. I have removed the starter and tested the solenoid on the bench, works every time, throws out hard and makes the high current contacts that provide power for cranking. I have reinstalled the starter and tried shimming just in case the aftermarket starter is dragging on the ring gear preventing the solenoid from fully engaging, no joy.

It seams as if the solenoid is not strong enough to fully engage on the ring gear and make the high current contacts to motor the starter, or somehow the bendix is binding up when the starter is bolted up but not on the bench. I proved this by measuring zero voltage on the starter motor side of the solenoid with the key on and audible engagement "click" verified when it's exhibiting the problem.

I'm going to swap the solenoid from the new starter to my old one and try it. Beyond that I don't know what else to try.

Any ideas?

Thanks in advance, Mark

 

[Bt Doctur]

Re: Mercruiser 3l starter/solinoid problem, stumped

Are you sure it`s not the slave solenoid causing the problem.It supplies the power to the starters solenoid.

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

Yep, I put a jumper accross the slave and could hear and feel the starter solenoid throw out but no cranking. Unless bad contacts in the slave solenoid could cause a weak starter solenoid engagement?

 

[JustJason]

Re: Mercruiser 3l starter/solinoid problem, stumped

Inspected power and ground cables and they are free of corrosion

Unless you sliced them right down then middle there is no other way of telling wether your cables are good or bad except for this....

http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103

Your answer lies in that test.

 

[Bt Doctur]

Re: Mercruiser 3l starter/solinoid problem, stumped

Lets go back to some basics
battery cables and ends clean and tight especially the neg at the engine block
On your starter is a red wire that supplies power to the main system, goes thru the 50A breaker and then supplies power with the red wire on the slave.
thru the slave with the yel/red wire to the main starter solenoid.
Low current may not allow the starters solenoid to pull in fully.
If you can short the starter solenoid with a jumper and it works all the time ,then it might be a corroded wire someplace or just a loose/corroded connection
http://www.boatfix.com/merc/Techbk/96/96HGD4.PDF
might find some useful info in here

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

I'm confident that the electrical conections are all clean and tight. I had removed them from the battery, the starter and the engine block ground and cleaned the ring terminals with a scotchbrite pad in a die grinder within an inch of their life. I pulled the boots back at the ring termials on the battery positive cable at both ends an the crimps are tight, connection is clean, the wire is shinny copper with no evedence of corrosion, but I will check again to be sure.

The starter solenoid activates every time the key is turned to start but most times not enough to make the cantacts that send power to the starter windings. I'm beguining to think that the solenoid on the new starter is not up to the task.

Mark

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

Hi,

I worked on it for a couple of hours tonight and I think I have the problem tracked down to the slave solenoid as several have suggested and I had begun to suspect.

I took the boards advice and got back to basics. I started by measuring for voltage at the starter solenoid with the key turned to start. I found that when using the key the solenoid did not fully engage but when jumpered from the battery to the starter solenoid the starter would engage and I would see voltage on both sides of the solenoid. I systematically retraced the wiring and measured for battery voltage at each termination and found that I had a 6V drop across the contacts of the slave solenoid. This left only 6V to actuate the starter solenoid and as it turns out that's not enough.

I will pick up a replacement slave solenoid tomorrow and try it. I will post the results.

Mark

 

[JustJason]

Re: Mercruiser 3l starter/solinoid problem, stumped

found that I had a 6V drop across the contacts of the slave solenoid

Funny what a voltage drop test will tell you eh??

 

[Cptkid570]

Re: Mercruiser 3l starter/solinoid problem, stumped

How many volts should you be getting at the starter solenoid? You said a 6 volt drop in the slave solenoid.. What are you testing at the slave? Just wondering because I have a similar problem..

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

Hi,

First thing to do if you have not allready is get a wiring diagram for your installation. Check the link in the post by bt doctur. Then start at the battery and measure the battery voltage. I measured 12.5V accross the battery terminals, that's typical for a 12 volt system at full charge. Then check for voltage at the battery cable where it attaches to the solenoid at the starter, I had 12.5V. Then I checked at both sides of the curcuit breaker on top of the engine 12.5V again. Then I checked at the battery side of the slave solenoid, 12.5V. Then I turned the key to start to close the slave solenoid and checked for voltage on the opposite terminal of the slave solenoid and only got 6.5V. With the key still in the start position I measured at the starter solenoid and confirmed only 6.5V available.

Even though you here the starter solenoid click it is not fully engaging and applying power to the starter windings in this low voltage condition.

It's worth restating that a loose connection or corrosion in the wire crimps or ring terminals will cause the same situation. Any resistance in the circuit will draw down the voltage at the starter solenoid.

Hope this helps, Mark

 

[Cptkid570]

Re: Mercruiser 3l starter/solinoid problem, stumped

Thank you for the quick reply and the detailed description! That will really help a lot of people (including me).

When you are done replacing your slave solenoid, could you post back into here and let us know how it works?

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

will do, picking up the solenoid this afternoon.

Mark

 

[Cptkid570]

Re: Mercruiser 3l starter/solinoid problem, stumped

Where are you getting your part from? Seems like a $20 part regardless of whether you buy it from an online place like ebasicpower or iboats or whether you get it from West Marine or a Mercruiser dealer.

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

I picked up the part at the local Marina, $26 with taxes. When you live in Canada you get used to everything costing 30% more than what you see on a US website. That includes 15 cents on the dollar for exchange rate and 15 % sales tax. If I'd have bought the same thing with a Mercury part number on it would have cost double that, but I'm glad I didn't because it didn't cure the problem.

That's right, I rushed to the Marina after work, Bought the part, brought it home and installed it...click....click....click....what the #$%@.

Now I really had to take a step back and try to wrap my head around this one. I duplicated the voltage drop tests with the same results as the old slave solenoid. By the time I got to the slave solenoid with the key on and the starter solenoid coil energized the voltage was drawing down to 6.5V. So I cleaned all the connections in the starter solenoid circuit again and when I was done I rechecked the voltage drops at each step. This time I had the starter solenoid wire disconnected at the starter I measured 11.5V. Bingo!

No way, hook the wire up and the solenoid coil draws the voltage down to about 9V and a weak solenoid engagement. Time to take a look at the third component in any electrical circuit, current flow. I had everything clean, I had the components tested and when I applied 12V from the battery to the starter solenoid via a jumper wire it works fine. So what haven't I checked?

On my installation there is a little gubbins mounted under the main battery lead at the starter solenoid that I find out is called a "fuse". I only know it's a fuse because I stumbled across it when checking prices for the slave solenoid. This component is not on the wiring diagram so I had basically ignored it through this whole process. You can see one here.

http://www.iboats.com/Mercruiser_In...3542936--**********.828414359--view_id.270978

The fuse is positioned in the circuit between the hot lead from the battery and the power feed for the starter solenoid circuit. Could this thing be limiting the current available to the solenoid? I decided there must be corrosion or something going on inside this thing so I took it apart. Low and behold the fuse element fell into two pieces when I had it disassembled. I could tell it was melted and must have just made enough contact to intermittently let enough current through to activate the solenoid.

Now What. I wanted to test my theory so I dumped the guts out of this little component, repositioned the insulator portion, added a washer to take up the space where the fuse element was and bolted it back together. It's no longer a fuse but it is a junction block. I put the thing in and went for a test. I've started the engine half a dozed times now without the slightest hesitation.

It's fixed! Sort of. I guess I need to get a new fuse and install it. The charging leed from the alternator also attaches through this fuse so in the case that your alternator goes crazy and startes to overcharge the fuse will blow and protect the battery and wiring. It'll also leave you dead in the water, but just like Moms old Chevy you can easily jump the solenoid circuit with a screw driver and get a start out of it, which is what I should have done the first time this problem left me on the water.

Hope this story helps sombody.

Mark

 

[patsyjoe]

Re: Mercruiser 3l starter/solinoid problem, stumped

Hey Mark,

|thanks for the detailed post, just goes to show, everyday is a school day.

I never knew that part was a fuse. Wonder could this be my problem too.

Do you know does this fuse effect the fuel pump or is it specifically for the starter?

 

[mckeemm]

Re: Mercruiser 3l starter/solinoid problem, stumped

This is how I believe it works.

This fuse is rated at 90 Amps and is in the main electrical feed/charging circuit in series with the 60 Amp breaker on the top of the engine.

The 60A breaker will protect the electrical system from high loads (failed component, short circuit) and the 90A fuse protects the battery from an over charging situation (failed regulator, battery internal short).

In my case last fall my battery was failing during winterization. I had a heck of a time getting enough starts out of it to get the work done. As a result of all the poor starting the starter solenoid failed too (confirmed on the bench). I suspect that between the bad starts and boosting from the car etc. that the fuse was damaged. I changed the starter last fall. I found one cell frozen in the battery this winter which confirmed the battery was on the way out. I subsequently brought the battery back to life but don't trust it so it was replaced as well.

Then this spring the starting problems continued. Something was preventing the starter solenoid coil from getting enough current to fully actuate. I was looking for a failed component or high resistance in the system from bad connections or corrosion etc. which is the most common cause. Once I eliminated all that I was a bit frazzled. The one component that I really hadn't checked was the fuse, and until yesterday I didn't even know it was a "fuse" or I quite likely would have checked it sooner. So how do you check it? I put a meter across it and it had continuity, (I don't remember checking resistance) I checked for voltage and battery voltage was present. I still didn't trust it so I took it apart and found the fuse element melted and it fell apart in my hands. Then I reassembled the pieces in such a way that it was now a terminal block with no fuse element to test it. It works fine.

Looking back, all I had to do was place a good heavy jumper across the contacts to bypass the "fuse". Proper operation would confirm the fuse is at fault. This type of fault will show up when high loads are applied. Starter solenoids (coils) and fuel pumps (motors) are high loads. If you jumper the fuse and you get proper fuel pump operation then you have found your problem.

Mark