Hot Start/Electical Problem

[haulnazz15]

Alright electrical guru's, I have a bit of an issue. With a cold engine, everything starts up perfectly with no issues, the blower (electical bilge blower) operates, as does the bilge pump. Guages all work perfectly. After running for a bit 20-30 minutes, we shut down the engine just to inspect things and look things over (new engine approx 3-4hrs).

Now the issue: when we go to restart with the engine hot (i just mean warm, temp around 130-140) the engine will crank about 1/4 turn and stop like the battery is dead. The blower will not turn on, nor does the bilge pump. So, we let it set for about 15 minutes or so to cool off, turn the key, and it fires up like nothing was wrong. We go ahead and run it the 30 minutes or so back to the ramp without an issue, and the blower was working when we pulled the throttle back at the no-wake buoy. WTH?!!

Fast facts:

Had starter rebuilt when we rebuilt engine
Blower is new Rhule inline-type
Battery is new, which is a replacement of previous new battery that we thought was causing this issue.
Battery positive and negative 4ga cables are new.
Alternator is original 1976-spec, but amp gauge shows a positive charge when engine running.
Guage needles operate correctly regardless of electrical issue

I'd really like to figure this one out since it's the last piece of the puzzle to getting the boat back to it's wonderful self!

 

[wire2]

Re: Hot Start/Electical Problem

You're going to have to take a few voltmeter readings when it does that. First at battery, then at starter (while trying to crank).
If ~ normal, pull the plugs and try to crank engine. Does anything come out of spark plug holes?

 

[haulnazz15]

Re: Hot Start/Electical Problem

Spark plugs are dry/everything is normal. I didn't think you could put a voltimeter on the starter when cranking due to the possibility of frying the voltimeter? I guess my major question would be why would the blower/bilge pump stop working if the gauges still function? They are on an entirely different wiring harness from the engine.

 

[wire2]

Re: Hot Start/Electical Problem

Spark plugs are dry/everything is normal. I didn't think you could put a voltimeter on the starter when cranking due to the possibility of frying the voltimeter? I guess my major question would be why would the blower/bilge pump stop working if the gauges still function? They are on an entirely different wiring harness from the engine.

A voltmeter will work fine, you're thinking of an ammeter. Use aligator clip leads to avoid looking like Houdini to reach in there.

I believe some voltage readings will pinpoint the fault. I'm guessing it's a single electrical connection somewhere near the engine, possibly on the negative side.

 

[haulnazz15]

Re: Hot Start/Electical Problem

Yeah, I hope that's all it is. I'd hate to have to replace the engine harness and the accessories harness just to flush out a single wire. I should be looking for over twelve volts at the battery and the starter correct? If I have less than twelve volts at the starter after the incident occurs, where would I check next? Also, why would this only occur on a hot start?

 

[Silvertip]

Re: Hot Start/Electical Problem

You are looking at the large positive cable from the battery. Check voltage at the battery while attempting to crank the engine. If it pulls much below 11 volts I'd suspect the starter rebuild was not done correctly. If the voltage stays at 12 volts, even though the engine does not crank or cranks slowly, THEN move to the starter solenoid (large terminal) and repeat the test. Make your tests on the threaded terminals not the cable ends. This helps determine loose or corroded connections. If voltages at the battery were normal but not at the solenoid lug, then you have a suspect cable or cable end. The ground cable is subject to the same issues but you can't measure voltages from ground to ground so ensure those connections are clean and tight. (Looking is not a test -- it is an observation!)

 

[haulnazz15]

Re: Hot Start/Electical Problem

You are looking at the large positive cable from the battery. Check voltage at the battery while attempting to crank the engine. If it pulls much below 11 volts I'd suspect the starter rebuild was not done correctly. If the voltage stays at 12 volts, even though the engine does not crank or cranks slowly, THEN move to the starter solenoid (large terminal) and repeat the test. Make your tests on the threaded terminals not the cable ends. This helps determine loose or corroded connections. If voltages at the battery were normal but not at the solenoid lug, then you have a suspect cable or cable end. The ground cable is subject to the same issues but you can't measure voltages from ground to ground so ensure those connections are clean and tight. (Looking is not a test -- it is an observation!)

Okay, so assume the voltimeter reads 11 volts or less during cranking, why would the blower/bilge pump be inoperable? I understand they need 12V as well, but would the battery's voltage remain below 12V even after you stop trying to crank the engine?

I apologize about all of the theoretical questions, but I'm trying to understand how the symptoms are interrelated.

 

[CheapboatKev]

Re: Hot Start/Electical Problem

Okay, so assume the voltimeter reads 11 volts or less during cranking, why would the blower/bilge pump be inoperable? I understand they need 12V as well, but would the battery's voltage remain below 12V even after you stop trying to crank the engine?

I apologize about all of the theoretical questions, but I'm trying to understand how the symptoms are interrelated.

Perhaps the blower/bilge share the ground and there is a bad connection there....

 

[haulnazz15]

Re: Hot Start/Electical Problem

The blower has a direct ground to the starter bolt. The bilge pump also has a direct ground to the starter bolt. They both function normally until the hot start issue occurs, so I would assume something is shorting out. The blower has a positive cable directly to the battery with nothing but a toggle switch in-between. I have it hardwired at the moment (yes I understand fuablelink/fused connections, etc can prevent a fire). The bligle pump runs through the factory harness up to the helm station switch. They both fail to operate and only share the ground connection in common and the battery itself.

I have to assume at this point since I'm not near the boat at the moment to test it. If the battery is shorted out or something when the hot-start occurs, maybe the battery drops below a voltage level where the blower/bilge pump can operate. I'm trying to figure out what would change between hot versus cold starts. Could the electric choke be causing something?

 

[mkast]

Re: Hot Start/Electical Problem

Now the issue: when we go to restart with the engine hot (i just mean warm, temp around 130-140) the engine will crank about 1/4 turn and stop like the battery is dead.

My first thought is, how hot are the battery cables when this happens?

 

[haulnazz15]

Re: Hot Start/Electical Problem

My first thought is, how hot are the battery cables when this happens?

It never occured to me to check, but I've never seen any smoke or sparks. I will be sure to give it a quick touch to verify they aren't cooking my battery.

 

[Don S]

Re: Hot Start/Electical Problem

The battery connections need to be clean and tight (with a wrench) the cables also need to be in good shape. I have had people bring in boats and say they tightened the connections only to find the ring terminal on the end of the cable is only holding on by a few strands of the cable. Have also found cables that have wide spots in the middle of the cable due to corrosion.
The only thing to do is replace the cables.

You could also have a faulty battery, or even the timing being way off or a combination of both

 

[haulnazz15]

Re: Hot Start/Electical Problem

Let me clarify, these are NEW positive/negative cables, wrench tightned to both battery terminals and to the starter solonoid. I also have a new cable going from the solonoid to the starter (Ford 351w, so separate solonoid). Battery is new 800+CCA which was bought less than a month ago. We replaced a battery that was also new when this problem first occured because we thought maybe it had a faulty plate.

I firmly believe the problem has to lie with an open short related to the starter, alternator, or harness. I cannot see it being a problem with the battery, or the feed cables to the starter/starter solonoid/ground.

This non start occurs after the engine has been running and up to operating temp. The starter will "bump" but will not turn the engine more than 1/4 turn or so, then nothing. This is NOT a case of engine turning but not firing. The timing is set a 10 BTDC verified with a timing light twice, which shouldn't be of much consequence.

 

[mkast]

Re: Hot Start/Electical Problem

This non start occurs after the engine has been running and up to operating temp. The starter will "bump" but will not turn the engine more than 1/4 turn or so, then nothing.

Starter will engage, will not keep turning the engine over.
High resistance.
That high resistance has to be traded off as heat somewhere.

 

[18WCmerc]

Re: Hot Start/Electical Problem

sounds like a large gauge wire is about to leak smoke lol, i hear electrical components seize to operate when they are empty on smoke.

 

[haulnazz15]

Re: Hot Start/Electical Problem

Starter will engage, will not keep turning the engine over.
High resistance.
That high resistance has to be traded off as heat somewhere.

I agree, unless the battery is being drained/shorted out during engine operation somehow. I know the amp gauge showed a slight positive charge but near "0" while running down the lake, so the battery wasn't needing much of a charge from the alternator. It's is a single wire system for the alternator, so I can't have wired it improperly (at least I dont think! ).

The starter is not remaining engaged, so I can't see how the starter would be related. I would suspect some issue with the ignition switch wiring, but I don't get why it would only have an issue on a hot start unless some wiring is heating up and causing a short. The electric chocke and the distributor are both getting a constant 12V from the same wire I believe (Pertronix, so no ballast resistor).

 

[Don S]

Re: Hot Start/Electical Problem

That is why I hate amp meters. Too many connections in too many places and too long a run of wire. All your power has to go from the alternator to the helm and back to the engine to charge anything.
I would be looking at all the connections (especially the main engine harness plug) on the Red and the Red/white wire. If it goes dead when warm, then you loose accessories also.

 

[haulnazz15]

Re: Hot Start/Electical Problem

That is why I hate amp meters. Too many connections in too many places and too long a run of wire. All your power has to go from the alternator to the helm and back to the engine to charge anything.
I would be looking at all the connections (especially the main engine harness plug) on the Red and the Red/white wire. If it goes dead when warm, then you loose accessories also.

I understand that, but the blower is wired directly to the battery, so even if the red or red/white went bad, the blower should still function right? Just to be a little more clear, I have the blower wired to a toggle switch located in-line in the bilge area. This completely bypasses any harness engine or otherwise. The blower still stops dead when the starting issue occurs. however, it kicked back on like nothing was wrong after we let the engine sit for a bit and restarted.

 

[CheapboatKev]

Re: Hot Start/Electical Problem

I understand that, but the blower is wired directly to the battery, so even if the red or red/white went bad, the blower should still function right? Just to be a little more clear, I have the blower wired to a toggle switch located in-line in the bilge area. This completely bypasses any harness engine or otherwise. The blower still stops dead when the starting issue occurs. however, it kicked back on like nothing was wrong after we let the engine sit for a bit and restarted.

Wonder if your battery is way overheated and stops putting out any juice till it cools back down if thats the case????

 

[haulnazz15]

Re: Hot Start/Electical Problem

I'm not sure, I suppose I could wire in a voltimeter pretty easily to view what the alternator is putting out while underway, but unless the voltage regulator is failing, I would expect to see between 12-14V. Once it sits for a bit, the engine cranks like there was never an issue and engine fires over after one turn or less.