1996 mariner 175 efi ignition problems?

[Dewey]

When first started, I will have to feather the throtle in order to keep the engine from stalling out. It will run fine at first when I open it up but will eventually start to go through a phase in which it surges then bogs down then surges and bogs down the RPM's will drop and surge to where they are supposed to be. When I tilt the motor up or down while running it drops the RPM's and dims the lights. I have checked and replaced the battery. When I looked under the hood, I found that the two yellow wires on the top rectifier melted through the bullet connector rubber and were touching. I replaced that rectifier and am not sure what to do next. I guess it could be the stator (hopefully not) or one of the switch boxes. Any help would be greatly appreciated.
Dwayne

 

[Faztbullet]

Re: 1996 mariner 175 efi ignition problems?

What is your battery voltage when running? Sounds like you have high resistance or broken battery cable. The stator may be damaged but the yellows are the charge circuit. A bad ground or positive will effect the ECU and fuel pump circuit.

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

thanks for the help. how can i locate the resistance? should i just hook up an ohmeter to the cable and measure the resistance across the cable? what should the voltage be when it is running?

 

[CharlieB]

Re: 1996 mariner 175 efi ignition problems?

An intermittent short near the regulator WILL affect the fields in the stator which in turn will affect/weaken spark intensity and limit power.

This stator uses parallel charging circuits.
If you have cured the cause of the short, BOTH charging coils on the stator check out, and BOTH of the charging systems are functioning again, then retest the motor, you may be chasing a problem that you've already fixed.

What is battery voltage, engine off vs engine running on the garden hose at 15-1800 rpm?
Disconnect one rectifier at a time so as to test one half the charging system (one set of charging coils in the stator) Then test with both sides/rectifiers connected.
If one charging system fails, DVA test both stator charging outputs as the stator may be hurt.

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

thanks for the help so far. I have checked the battery when off and it is around 13.5 or 14 volts. When the engine is running with one rectifier it is up over 15 at the battery and same with the other rectifier. I have not been able to put the boat in the water yet but it is still idling rough when i am using the garden hose. I checked both sets of charging leads from the stator and both are putting out about the same voltages. it is hard to tell how many rpms when i disconnect the other rectifier that controls the tach. Any other ideas as to why it does not want to idle nicely? thanks again.

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

I just checked to see if the tilt will still suck power and it does. I see the lights dim and the battery gauge drops down to about 12 volts or a little less and the comes right back up after. I don't think that is normal? this is while the engine is running.

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

I went out yesterday and was not able to open the throttle up. The boat would not Idle well at all and running the power tilt still had a huge effect on the motors ability to continue running. It seems as though there just is not enough power going to everything. I thought about running two batteries one for the motor and one for accessories but i am affraid I would not be fixing the problem only masking it. How can I tell if the Stator is producing enough voltage. I know that it is but how much is enough?

 

[Faztbullet]

Re: 1996 mariner 175 efi ignition problems?

Check all your grounds. you are going to find a bad ground strap broken or loose somewhere.

 

[CharlieB]

Re: 1996 mariner 175 efi ignition problems?

I not sure about that stator.

Using a DVA meter you should get a high voltage on the low speed windings and a low voltage on the high speed windings either at cranking speed or at an idle. Without looking at the chart your readings should be in the area 180-200 volts on the low speed windings and 25 volts on the high speed windings.

The high and low speed outputs should NOT be near the same unless you are testing at about 2000 rpm.

If Both switch boxes are not receiving these inputs from the stator then you have a problem with the stator.

 

[CharlieB]

Re: 1996 mariner 175 efi ignition problems?

A poor ground or poor connection between the battery and the trim motor will draw amps and lower available voltage to the EFI computer and have an immediate effect on fuel delivery.

The stator high/low windings effect only the ignition systems.

You may not be testing stator output correctly and not have any problem with the ignition but only a poor connection battery to trim somewhere.

Then again you could be running in circles dealing with two totally separate problems.

Try running a search here looking for details on voltage drop testing, test all connections battery to trim to locate that problem first, then retest the motor on the water, you could be fine then.

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

I have gone through the grounds and cannot find a loose one. This is becoming a big head ache. The boat will run if I have to run it but I don't want to mess anything up more than it is. The engine continues to go through a cycle of high voltage then low voltage at idle before conking out. The plugs are fouled nice and rich. I tested the resistance of the stator and checked for a short to ground and came up with nothing. I do not have the tools to check output for it so I am stuck there. I tried disconnecting the trim motor to see if that had a short somewhere and the motor ran the same way. what else could have happened when those two yellow leads from the stator shorted to each other? What is next?

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

could it be fuel line related? Please help me
Thanks,
Dwayne

 

[Ed R]

Re: 1996 mariner 175 efi ignition problems?

Hey Dewey, sounds like the stator and regulators are doing their job. Is the battery able to hold and maintain a charge? sounds like a bad battery.
The running characteristics are a different issue. The ECU will run with as little of 10 volts. It is normal for this type of efi to react to power trimvariations. This motor relies on sensors, tpi, temp and air (map). one of these is probably at fault and is hard to diagnose with out more detailed info.
but we can try if needed. good luck. Ed

 

[Dewey]

Re: 1996 mariner 175 efi ignition problems?

well I broke down and took the boat to the shop. It turns out the map sensor is bad and they have to replace the ECU. Does that sound right? It is not cheap $1700 for the ECU. What makes them go bad? My mechanic said that over 30+ years of experience he has only seen a handfull go bad. Thanks for the help.