Carb vs EFI ?

[David]

I don't know about running a 25" all the way up on the jackplate. It will raise the center of gravity, so maybe watch it cornering?

On the other hand, a 15" mid is supposed to handle better than a 20" mid on my SS2000, or so I am told. I don't see much difference.

[skialot2]

I don't know about running a 25" all the way up on the jackplate. It will raise the center of gravity, so maybe watch it cornering?

On the other hand, a 15" mid is supposed to handle better than a 20" mid on my SS2000, or so I am told. I don't see much difference.

That was just an idea to try it out. But i switched it to a 20" mid. A 15" mid would be too short for my boat. The motor would literally sit just above water. The motor already gets swamped when I come off plane.

[Glastron1987]

Carbs definitely easier to diagnose, efi will start easier cold, a good set carbs that's jetted just right idle perfect and never miss a beat, starts real easy warm , can rejet carbs for power mods instead having ecu modified, more Reed noise with carbs and little dirtier under cowl. I lean my idle jets out (it will idle at higher rpm but I start n gear) and there's no bog and great throttle response then jet mains according, carbs prob little more thirsty but how thirsty depends on carbs you choose to run , if i was to run efi I would want hipo efi not laser /consumer efi just my .02

If you lean out the carbs for good idle and it idles too high, can't you adjust the timing to accommodate for that?

[Merc 2.5]

If you lean out the carbs for good idle and it idles too high, can't you adjust the timing to accommodate for that?

Ya u can depending how lean you go , but i start in gear anyway so don't bother me either way , i idle n neutral round 1100-1200, 850 or so in gear roughly, but it makes right off idle ,hole shot night and day difference

[KIRCHNER]

ill put in my 2 cents, i changed the shape on my efi throttle plastic cam with jb weld. response was great before, now off the charts. thought i spun the hub out. made the ramp come in earlier+ little steeper. doesnt take much. hey m25, were you once looking for a quad-r-jet,propco?

[skialot2]

I found a main EFI harness for cheap enough, so I bought it and dissected it. There was only 3 wires I actually had to cut to separate the EFI harness from the main harness. A ground. The purple switched hot. And the start wire to the solenoid. Then I disassembled the plug to the controller. The Green, Green and Red and Green and White. They go to the same color wires on the inner switch box. There is a black and white wire that connects to the bias connection on the switch boxes. The only wire I am not sure what to do with it is the blue wire from the water alarm on the fuel filter. It usually connects to the oil warning module. But I am not using oil injection. I think the water sensor has its own module so I am hoping I can just connect the blue wire to the overheat alarm. If not, I guess I will just not use the water alarm.

[tlwjkw]

tha water alarm thingy doesn't work (even on a stock production efi) most of tha time anyway...... jmo.

[LakeFever]

Yep ditch all the nanny stuff it’s just distraction imo

[skialot2]

I switched everything over. I took all the CDM ignition off the motor and the EFI harness off with it. I put my dissected harness on. I wanted to be absolutely sure the ignition system is good. So, I took all the CD ignition off my 2.5 200 carb motor. That way, if it doesn't run good, I know it's a fuel injection problem. The exhaust cover is different. I had to mount the regulators to the coil plate. Then mount the coil plate to the motor with just 1 bolt. Just to try it out. If it runs good, I will mount it properly. I had to extend 2 wires. Just the black and white bias wire and the green ignition wire for the EFI harness to the inner switch box. They both also go to the detonation module so I could not reroute them. It started right up. It idols good. It seems to rev up smooth and with a little more zing than it had before. I am going to have to try it out the next halfway decent day.

[skialot2]

Well, it was a nice day today. So, I threw the boat in to see if it is fixed. Nope! Runs exactly the same. Starts with a click of the key. Idols good, revs up fine in neutral. But when you give it gas it just doesn't go. Apparently, it is not an ignition problem. It has to be something with the fuel injection. I already tested and adjusted the TPS. That works fine. I need to find an adapter for my fuel pressure gauge. I am hoping it is low fuel pressure. Does anyone know how to check to see if the ECM is working properly?

[OnPad]

Idk if it will make much difference, but get rid of whatever that black/white wire is hooked to, and then ground that wire. Thinking that the temp sensors are good for +/- 10% fuel. The injectors are testable with a dva, or visually, and the fuel pump with a gauge, and volume test.
There's also a map sensor built in to the ecu, that should do something when a bit of vacuum is applied.

[skialot2]

The black/white wire is connected from the bias wire on the switch boxes to the detonation module. For some reason the detonation module is only used on 200's. It's not used on 150's or 175's. So I probably could get rid of it. The models that don't have it, have either a shift switch or the gray/white wire from the ECM is grounded. Yes, the temp sensors are good for 10% richer or leaner. I unplugged the air temp sender, then it didn't want to idol. That seem like it's working. I definitely need to test the fuel pump. I turned the key on for about 20 seconds without starting it. Just let the pump run to build pressure. Quickly pushed the Schrader test valve. Not much fuel came out.

[OnPad]

Your wiring description sounds about right. I deleted the det. module on a couple of 200's, but it's been a while.
Did you set the timing after swapping the trigger? Speaking of timing light, I guess the first thing to do, would be to figure if ya have a ignition, or fuel problem.

Much of the ecu testing can be done with the tests in my last post. That confuser box has been known to have problems with the pump driver, and sometimes map. Merc made a special ecu tester. If you can find one?

[skialot2]

Yes, I set the timing. Definitely not an ignition problem. I switched the ignition from CDM back to CD. I took the entire ignition system from my good running carb motor. It runs exactly the same as before. And yes, a DDT is really hard to find. And if you could find one, it would probably be about a million bucks.

[skialot2]

I ran a bunch of tests. I already tested and set the TPS when I did the link and sync. I just tested the fuel pressure. It's good at 39psi. I unplugged the detonation module to disconnect it. That made no difference. I tested both the air temp sender and the head temp sender with an ohm meter and the ice water / hot water test. Both senders work perfectly within the proper ohm scale. I also did a leak down test. All cylinders tested perfect. Almost no leak down at all. 96-97%. I don't think there is anything else it could be except the ECM. This motor has an A30. I just picked up 2 A8's. I hope they interchange. Otherwise, I am going to have to change the harness.