Ecm cost

srl

Member
May 20, 2013
103
Fort myers FL.
Boat Info
08 Amberjack 29'
Engines
2x 350 mag Bravo 3 sea core
My port engine does not start. The mechanic found that it wasn't getting fuel and replaced the fuel pump gaskets, then found no power to the pump; found a breaker on the firewall, reset it and the engine ran fine. In taking the boat out the next day the engine died a couple of times right after start-up but ran fine the rest of the day. The next day the engine would not start, no power to the pump again. The mechanic now thinks it may be the ECM. Is there anything else that could cause the problem? How much does an ECM cost for a Mercruiser 5.7 mag mpi fwc Bravo?
 
Before I spent that much money I would verify no power AT the plug end. For Cool Fuel and Cool Fuel III you can install a oil pressure switch and a manual primer button.
Would need a engine serial number to check the wiring
 
Bt, I think the mechanic said he didn't hear it click but I'm not sure, I'll have to ask him. Thanks for the schematic.
 
Last edited:
Talked to mechanic, he said the relay works when connected to the other engine. Waiting for his return.
 
At location A and remove A-B fuse, jumper the connection .Pump relay should click if ECM is supplying the ground on the Dk/Green lead
Remove C-D fuse and jumper. this will supply 12v to feed the fuel pump thru the relay.

But remember the main power relay has to operate to supply the power to the 3 fuses .The Pink/Green (#22 pinout)goes to ground to turn the main relay on .
 
Mechanic swapped ECM with the one from the engine that runs and the formerly non-working engine then worked and the other engine then didn't. Does this prove that it is the ECM?
 
If that's the only part that was swapped, then I would saw yes, defective ECM.
 
Or the wiring connector to the ECM may have been loose and swapping the ECM's tightened the connector....may want to try putting the suspect ECM back in place to verify....

cliff
 
Cliff, if it was a loose plug on the non-starting engine, then I would think when it was swapped it should have worked on the engine it was currently on.
 
Cliff, if it was a loose plug on the non-starting engine, then I would think when it was swapped it should have worked on the engine it was currently on.

good point....I did not read your post close enough....sorry....

cliff
 
Locate the Dark Green wire at pin 19 of the A plug and ground it.At the fuse block you need power at pins B and D
If the pump now works its a ecm issue, if it does not work its a wiring issue
You need 12v at pins 30 and 85 of the fuel pump relay plug and a ground at pin 86 of the relay plug
 
BT, wouldn't swapping the ECMs prove the problem is the ECM ( see my Thursday post ).
 
just to clarify, you swapped the ecm`s and the trouble follwed the ecm?
The ecm from the running motor corrected the no start condition on the other motor?
 
I'm still trying to figure out if the ECM is the current symptom or the original problem. On your first post, a breaker was reset ....the fuel pump got power and the boat ran "fine".

Then it blew the ECM. For starters, the ECM would not trip a fuel pump breaker. My concern is that you may be close to frying ECM number two if there is another electrical problem that needs to be sorted out. ECM's use signal voltage to the sensors, injectors and the engine components. If the ECM gets an accidental feed of 12 volts on one of these circuits.....it will cook that circuit.

My thought is that your mechanic needs to take a hard look at the amp draw on the fuel circuit and compare that to the other engine. Something isn't right that caused this to go wrong in the first place.
 
A few days before the present problem I had a no run codition. Mechanic found the fuel pump at fault, installed new gaskets and seals and motor ran. I took the boat for a few hours, no problem. I also did a re-start and it was fine. A couple of days later it would not start. The mechanic believes someone bypassed a 2amp fuse in line with the ECM which may have caused the ECM to go bad.
 
Ok.... The point I'm making is that something caused the ECM to go bad. I don't understand what caused it in the first place. Your description seems to say that the fuel pump was the original problem and once repaired the engine ran fine. Then, out of nowhere the ECM failed and resulted in a no-start condition. Your mechanic discovered that someone had "bypassed" a 2 amp fuse which he suggests may have caused the ECM to fail. Is this right?

The reason that this is important is to ensure that you don't fry the replacement ECM. I'm suspicious that something else caused the original ECM fail. After all.....why would anyone bypass a 2 amp fuse? That suggests that something on the end of that circuit was drawing more than 2 amps (causing the fuse to fail) and that the "fix" was to bypass the fuse.
 

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