Looking for advice on Ford based, EFI V8's from 1993-1996...

[MasterGoa]

Hi all.

I am trying here cause no one seems to have experience
from the OMC sub forum.

After fixing an electrical issue with the house side of a cruiser,
and having both alternators going through an isolator, I noticed
a massive improvement in ride quality, engine sound and also
reduced my fuel consumption by 2/3. That's right, tripled the mileage.

As I was enjoying this new found appreciation for my engines, I noticed
that the isolator was slowly going bad, with over 2V drop many times.
This made the battery charger go yellow on my house bank, getting
back to the slip after a ride.

So, I tried removing the isolator and having one alt for engines and one for
house. Unfortunately, the harsh and alcoholic behavior of the engines
are back.

I noticed that with the isolator, the alts would charge 14.6.
However, without, they charge 13.4.

If I stop the engines for 30 minutes, the engines run great, until I press the
trim button, sucking power from the circuit...

So, as the alternators are governed by the fuel injection (EEC IV),
do they actually have an offset voltage to allow for an isolator to be present?
Is an isolator required as it's voltage drop is part of the design?

Can this parameter be changed in the fuel injection's config?

Any help appreciated.

And am this close: () to having a perfectly running boat

 

[muc]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

What is your engine model?
The alternators are not governed by the fuel injection.
Guessing you have a wiring issue.
Is the “keep alive” wire connected to the battery post of the battery that runs the engine?
Do you have the OMC Ford fuel injection manual for your engine?
There are some diodes in your wiring harness that can cause some strange issues.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Thank you MUC for your reply.

The engines are 5FAPRJVN, both of them.

I have the Seloc manual. I have a pair of fused wires that go from the battery
to the back of the engines, as well as the two alternator + feeds that go
to the isolator (which I have removed right now) and the battery terminal
at the battery switch.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Also, could the alternator regulators have a built in drop in voltage
to account for the isolators?

 

[muc]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Model number is missing some. But it looks like you have 2 of the last ones made.
You really need to get the OMC or Volvo manual. Don’t think I would trust the Seloc.
I would recommend getting rid of the isolator and using a voltage sensitive combiner instead.
No, the regulators don’t have anything in them to account for voltage drop due to the isolators.

The Ford EFI engines came up at the marina yesterday and our parts guy (who was a tech back when we sold a lot of these) said “I remember those engines, not a lot of troubles with them once we figured out that they needed a really good battery and big battery cables. About the only thing I remember replacing on them was alternators – they seemed to be hard on alternators”.

I think you should get ahold of a real manual, make sure your boat is wired the way it should be, check your battery and check for voltage drops on your cables.

 

[bruceb58]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

I noticed that with the isolator, the alts would charge 14.6.
However, without, they charge 13.4.

Its very possible that can happen if the sense wire of the alternator goes around the isolator to one of the batteries.

I personally hate isolators because of the voltage drop issue, which the remote sensing is trying to solve. Only problem is that you have to pick one of the batteries to sense.

I like ACRs way better.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Thanks for the advice guys.

I tried to two alternator scheme, and even though I would come
back to the slip with the charger saying everything is OK, I was not
getting the engines to run smoothly.

So I installed a new isolator.
The alternators are back to charging 14.6V. up from 13.6v.
However, the isolator manual says that compensation diodes exist
in some alternators and have that 1V difference.

Having said this, I noticed that in injection voltage is dropping slowly, day after day.
Now, the left engines runs at 11.6V and the right one at 11.9v.

I double checked the EFI power cables with their 50A fuses and slightly
crimped the fuse holders for better contact.

So, the alternators charge well.
Voltage after the isolator is at 13.4 average, up from 12.8 with the old isolator.
Tried running no isolator but the alternators only charges 13.6.

Voltages from the guages (which I have checked) and in a few places
across the ECM show insufficient voltage and is dropping
slightly every time I use the boat.

So, hearing of diodes in some wires makes a lot of sense
as this boat had LOTS of 12v issues on the house side.

Does anyone know where I could get an OMC official manual?

I guess I will drop by my local Ford dealer.
One of the older mechanics actually had a 1994 Mustang GT
with these very engines...

I am told those engines, else a different cam, are identical
to car engines, including injection control. Is this true?

I will get my hands on an AMP meter as yeah, the engines seem to be hard
on the charging system...

 

[bruceb58]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

If the alternators are putting out 13.4V and the fuel injection system is at 11.9V, you have a major voltage drop somewhere. Time to start checking connections.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Yeah, Ford guy told me as well.

Will undue the rear panel to see behind the engines...

At least, I am pretty sure where it will end.

I have checked everything except where those EFI power wires go to the EFI.

But still, any more info on diode wires? That would explain a lot of what I am seeing...

 

[bruceb58]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

But still, any more info on diode wires? That would explain a lot of what I am seeing...

There is no such thing as diode wires.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

What about what muc referred to in post number 2?
Diodes in the harness?

 

[bruceb58]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

There might be diodes in the harness that power the fuel pump relays but they normally aren't used on FI engines.

 

[muc]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

There are 3 diodes and 1 resistor built into this harness. None of them have anything to do with the fuel pumps. Well I guess I should take that back, one is in the keep alive circuit and one is in the ECA wake-up circuit. The ECA controls the fuel pumps so maybe a person could say they have something to do with the fuel pumps.

“Is this the same as a car engine?” I have no idea. Sorry but I don’t work on cars --- only boats. My guess is they are different because these diodes are there to protect the EEC system from idiots who connect the battery backwards. Something the auto people don’t have to worry about as much. If somebody has done that in the past it is possible these diodes have been over stressed and are causing your problem. But that is just a guess. It gets very expensive to guess on EFI systems. More often than not untrained people start mucking around and add an extra problem. Troubleshooting can be very important.
I do know that the scan tool and breakout box are the same as auto and my guess is that you will need those tools to fix this engine.

You really should get the real manual. Maybe try a dealer or Ken Cook Company (the people who published them). Until you have that, we really can’t help much because when you post voltage readings we need to know where the positive and negative leads to the VOM are connected and how much load was on the circuit when the reading was taken.

You have a voltage drop somewhere and you need to find it! I’m somewhat surprised that you haven’t toasted something yet because these systems don’t like low voltages. But the Ford system was VERY durable.

If you go looking for a marine mechanic to fix this, please look for somebody who went to the OMC Ford fuel injection class. We spent a full week on this system. At Volvo we covered Ford and GM fuel injection in 4 days.

I just read this post and I’m sorry if I come across a little rough. But this system is fairly tough to diagnose.

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Fair enough.

I understand I need to scan the thing, but though I "understand" FI engines very well,
back in my mechanic days (20 years ago), I did not work on them...

I went through ebay and found MANY OMC EFI books, I guess I need to buy the JV
one. Many offer them with two letters. NC, BU, JV, etc. Do I need JV since those
letters are in my model number?

For your diode comment, I can truly see this boat having issues, not
because it was hooked up backwards, but because of issues with the house
12v, I really believe these engines spent the last 10 years starved in voltage.
They had bad conditions to work with.

Good news is, I have one last place to check and this is where the 12V EFI power
meets the EFI harness.

From the BRP diagram, I see there are 3 ring terminals, I fully suspect they are loose.

Need to remove the back bench and extra floor panel, but oh well.

Again, thank you very much for your help!
I appreciate it!

Virtual beers for you guys

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Well, traced the battery EFI cable and it passes through a breaker and then
gets back inside the wire strands, which are in loom...

I noticed that the breaker contacts were somewhat rusted but
not enough to cause problems...

I wish I knew where it went next...

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Here are the engine components:

Here is the EFI diagram:

I have yet to test the ECC relay, but yeah, this is where I stand.
12V fused wire from battery, to 12,5A relay, to ECC relay, to ECA it seems...

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Well, did a few tests and only the 12v coming from the ECA has issues, all other
power from battery is OK.

So, does this thing have a voltage regulator?
If so, can it be configured?

Since both engines are within 0.2v from each other, I could
assume an offset was configured because of charging or the boat's
state before I fixed it...

Seems I am very close to a solution!

 

[muc]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Where do you have 12 volts coming from the ECA?

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Volt gauges (checks with quality volt meter), relay on leads at a few relays.

I am at the maximum I can go without a computer reader
so I will seek help as I am missing tools...

I hope this ECA supports engine running diagnostic
and not only code reading.

At Volvo, and ECA is prices at 4250$ lolll

 

[MasterGoa]

Re: Looking for advice on Ford based, EFI V8's from 1993-1996...

Does anyone know where the ground for the ECA is bolted to the block?