Battery Hurting Efi 4 Stroke?

[Methodman]

Thinking my 115hp Merc 4 Stroke had fuel probs, i took it in to get it looked at, thinking it was fuel related.

Without replacing the fuel pump they said there was no probs they could see. they even ran their own fuel lines on their own tank.

Until i got home and relized one of my batteries was almost dead and the other had a lose conection on the lug where the solder had let go plus a fair bit of corrosion. I could start the boat no probs and it idoled fine but when i tryed to get some revs on the water it stuttered and wouldnt give me any revs so id have to crawl back to the ramp.

My settup is a switch, allowing me to use Battery ONE or Battery TWO or Both Batteries. Batteries are linked through an earth wire.

I would always use battery ONE.

I noticed it ran alot worse when the switch was on BOTH Batteries

Battery Two is basicaly dead.

I tryed to recharge battery Two and it never re charged.

my question is... Altho i have enough power to start on battery One, Will the EFI struggle to get enough power to keep it running under power, due to battery two being dead and the lose lug on battery one???

Would the flow of power be haulted by the dead battery?

The fact that it ran alot worse on both batteries has got me asking this question.

Im currently recharging battery One now but I thought id ask some of you first.

Thanks

Nath

[IWANNABROCK]

your dead battery would be taking the charge from the good battery which then the efi system has no power to run,fix your connection's and charge both battery's,would also recommend checking you charging system on motor and load testing your battery's to prevent further issue's. an auto elec will check battery's and charge output for cheap.

[Methodman]

Thanks mate.

The merc machanic said the psi was down alittle. But that would be because of the power flow you would think?

Plus that lose conection would prob be causing some dramas? It actualy fell out of the lug when i touched it.

Thanks again mate.

[Mik]

Nath

I just switched my system to twin batteries & had lined up a switch that sounds similar to yours. IE you can run off 1 battery, the other battery or both. Is yours a single switch?

In discussions with the boat mechanic he advised that I don't go with this switch as it will automatically start draining your crank battery (For the sake of this lets call that battery 1) if battery 2 loses charge. In an offshore situation that would be bad as you would be draining your crank battery & when you go to start up you find yourself with not enough power to kick the engine over.

Now, being the wiz electrician that I am, I just nodded & said uuhh!

Anyway, he showed me another type of switch which has 3 seperate and individual switches. You can still choose which battery is on, IE Battery 1 on, Battery 2 on or both. But the main difference as he described it was that this system allows charge priority to be given to the crank battery & also if you loose charge in battery 2 it will not automatically drain the crank battery. It all sounded a little confusing to me given that I just asumed that a battery switch serves the purpose of making sure you always have enough charge to start the engine no matter what your accessory system does to the 2nd battery, but apparently I was mistaken.

It would be good if someone with a bit more technical knowledge could chime in here & tell us their thoughts. Meanwhile I will try to find the make & model numbers of the two different types of switches I am talking about.

Sorry if I confused the issue here but I thought it may be relevant if your thinking of replacing / upgrading anything after your little problem.

By the way, my setup will be engine, engine gauges, engine tilt off battery 1 & all other accessories off battery 2.

Edited January 30, 2008 by Boofhead

[Methodman]

Boofhead,

Mate this is the switch i have.

My main question is not the switch but the battery issues i have, are they causing my 4 stroke efi to run like a dog???

Be nice to have an Auto Electrician has their input.

Nath

[Mik]

Nath

Ditto on the Auto sparky input.

I understand your prob is related to motor performance, just thought I'd add the above because if your motor performance is determined by battery power level it may be worth considering the switch options for the future. Just a thought anyway. Hope it works out for ya.

Here's the switch the mechanic recommended & yes, the switch you showed there is the one exactly that he says is not the best option. Anyway, I'm sure a more qualified member will give you some better advice than I can, I just grip the wheel & yell "Stop drinking the beer & pull in that fish!"

Cheers

PS - the switch you have seems to be pretty common so I'm sure they work fine. I just went off what the Mechanic told me which made sense at the time.

Edited January 31, 2008 by Boofhead

[Flightmanager]

G'day Nath ,

Modern engines with EFI and digital ignitions require good constant power to operate properly . If one of your batteries is worn out , or not holding a charge , then it is not supplying the optimum volts and amps needed to run the engine. Fix the bad connections , make sure the batterie/s are fully charged and see if that makes a difference. A badly corroded connection will not allow the full amount of power to be delivered to the engine.

As for the switching option, I run a 2 battery setup , with the single switch option. What I do is use BOTH batteries for first start of the day . Select BATT 1 for trip outbound , BATT 2 for inbound . If both batteries run low on power , running them in parrallel (BOTH mode) will usually provide enough power to start the engine. Using this method ensures that both batteries are charged during the course of the day .

The individual switch setup that Boof mentioned is the ideal , but if you cant afford that , doing it the other way is quite safe , and reliable.

Ross

[Methodman]

Well ive got the good battery on charge so ill have a go tonight.

Fingers crossed!

thanks boys

[IWANNABROCK]

Thanks mate.

The merc machanic said the psi was down alittle. But that would be because of the power flow you would think?

Plus that lose conection would prob be causing some dramas? It actualy fell out of the lug when i touched it.

Thanks again mate.

How low was the compression? how much variation between cylinder's? did they do a wet test and a dry test?

Edited January 31, 2008 by IWANNAJEWY

[Methodman]

Didnt really tell me what the compression was. Just told me it was alittle lower than normal.

He did all his testing in a water bin. I took it for a run in the river and it was worse that before I took it to him. But i noticed the switch was now on both batteries rather than the No.1 Batt i use all the time. And as batt 2 being dead.. id say thats why it ran alot worse. Like i said ...the wire on battery ONE in the lug had come lose, couldt see any sign of it being soldered either. Just like it was crimped and forgoten about. The wire fell out soon as i touched the wire. I know you need a strong fitting conection or it will be as good as useless.

Other than it being the Fuel pump... Im hoping this is the prob. Be alot easier fix than $600-$800 fuel pump replacement.

[warnie]

Boofhead,

My main question is not the switch but the battery issues i have, are they causing my 4 stroke efi to run like a dog???

.

Well nath i can tell you from experiance that whether it be due to either a bad terminal connection to the battery and when i say bad

i mean an inspection of the terminal connection will not reveal anything

if down slightly on voltage to the battery (like due to a lay off over winter for a couple weeks)

even if a slightly discharged battery to number two...... although running on number 1

that will be sufficiant enough to cause my starboard motor to run like a dog???? mine as you know are yammies but i have now come

to accept this situation when and if it occurs.....im suspecting in my case once the voltage drop's below 10 volts there is

not enough there to operate the fuel pump why in my case it only effects the starboard

and not the port i can only speculate...sounds like your experiencing that similar dilemma

to your one motor

Cheers Warnie.....

[Methodman]

Hey Warnie.

Mate sounds like it ay.

The feed back i have gotten all point me in the right direction.

Its either battery or fuel pump. Like you said a layover.. which was over 6 months down the coast (near Saltwater). I noticed the terminals last night they were green and shitty looking.

So i can safley say my batteries were in VERY POOR condition.

You wouldnt believe it.. we are on the eve of SWR too.

Supposed to go Saturday, no where near ready to go.

Too much attention on this bloody problem.

So if this doesnt work tonight we are going to head to JB for the week.

I can use the old mans boat down there.

Sounds like the fishing is dead up there anyway.. might be a blessing!

Anyway mate.. thanks for ya in-put.

Nearly beer time for us ay???

Ill hit ya up after my holiday to where?? who knows hahaha.

Nath