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454XL ECM Harness Fuse Trips

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95carver370

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I have a 95 Carver 370 with twin 454LXs (fuel injected). After cruising the boat at 3,200 rpm or so for 15 or 20 minutes, the port engine just dies. The 10amp ECM Wiring Harness is tripping. After the engine cools, the breker can be reset and the engine starts right up. Have replaced everything but the ECM and the harness (including the 10amp breaker).

Any idea? Very frustrating.
 
You can switch the ECU's between the engines and see if the breaker issue follows the ECU. If it does, the ECU is the likely suspect....good luck finding a new one though.

I'd check the connectors for everything downstream of the fuse...Corrosion will increase the current thru a connection, especially for the pumps. If they are all clean and secure, open the harness. Any damaged wires should be pretty easy to spot.
 
So if it is "good luck finding a new one", what does that mean....SOL? Are there no others options if this part goes bad on an XL series engine?
 
Thanks for you comments. Finding an ECU is not that hard, but they are very expensinve, $1,200 to $1,400. I will switch them and see what happens. Obviously, the fuel I burn "testing" gets quite expensive. Plus, no fun docking on one engine...........
 
a '95 ecu is a MEFI-1, and they haven't made them for several years now - you buy them used or rebuilt. I've seen kits for converting the MEFI-3 engines so they can use MEFI-4 ECU and imagine somebody has something for the -1's. You can buy a -4 for under $600 so, given the figure above, there's a lot of trading room.

I bet the fuel consumed in testing is still cheaper than the labor for a senior technician...which you still pay if they were participating.
 
Ok guys, so I switched out the ECMs today. Took her out for a ride, and 35 minutes later, I lost the port engine again. This is very frustrating. After sitting at the dock for about 90 minutes, she starts up again. Its interesting, as after the engine dies, and I try to start it again, when I turn the ignition, I do not get the tow "buzz" audible. Once it cools off, I turn the key, get the two buzz audible, and I know she will start right up. Any thoughts??
 
At least you are still up the $1200+ for an ECU....guess you can still buy some more fuel.

Is the fuse still opening up?

Sounds like it is time to start checking the harness. Most of the time, the culprit will be a bad connection, almost always crimped. Not uncommon for the bad one(s) to get hot but may be hard to determine due to engine heat.....maybe some aluminum foil and an IR temp gun will help.

Another known source for 'issues' are relays...they are fairly cheap and you may just wanna swap all of them.
 
Thanks. Yes, I guess I do not have to buy a new ECM (not yet anyway). I will give the relays a shot. I actually have a new harness, but I was avoiding the instalation. A lot of wires...........
 
Check the Ignition Switch Relay. This powers the ECM when the key is turned on. I lost mine this weekend. The relay was switching on/off/on at 3400 RPMs. I hope no damage was done. This is the third time I've changed it in two years and am looking for recommendations on what is killing the relay.
 
Does anyone have a part number on the ignition switch relay?? Having trouble finding it. I have to admit that this make sense. Someone left the ignition switch on for about three days (ok, it was me). As I look back, this is when the problems started (and added a lot of hours to my port engine).
 
I found an old email that infers, for 454XLs, crusader #98175 is functionally equivalent to a gp-sorenson MR44 = Standard RY-109; the latter two may be readily available locally.
 
Okay, so I ordered the ingnition switch relay, installed it, and thought I was off to the races. No deal. Took her out for a ride and the exact same thing happened, the port engine died at 3300 RPM after about 20 minutes. Let her sit for 45 minutes, reset the 30 amp breaker, and it started right up. This si killing me.
 
Sorry, no it is the 10 amp fuse (I guess thats a fuse, even though it can be reset). The first one from the top that says "ECM Harness". Must have been tired (or annoyed) when I wrote the last post. I think the only thing left to do is pull the harness and follow/test each wire to see if there is a break or tear.
 
Okay makomark, you win, it is a "breaker" by definition. Question: Since it is the fuel that is cutting out, and when the engine dies it starts right up after cooling for 45 min to an hour, could the oil pressure switch be the issue? This switch cuts the fuel....
 
If the 30 Amp breaker trips, it's either seeing a overload or the breaker is bad. I've even seen a loose connection at the breaker causing this trouble. They usually spec inexpensive (cheap) thermal breakers here. I'd dive into the breaker, check the connection, if they both are good, replace the breaker. Lots easier than wiring harness swaps.
 
Dave's observation on the breaker is a good start.

I'd get the breaker to stop tripping before I'd worry about the oil pressure safety switch.
 
I am having the same problem on my 7.5 KW Kohler generator. It runs 30 minutes and stops like the switch was turned off. Last time this happened the magneto coil was shorted when it got hot. The short cleared when it cooled down. I wonder if you could be having the same or similiar problem.


Chuck Hanson
 
95carver370 said:
Ok guys, so I switched out the ECMs today. Took her out for a ride, and 35 minutes later, I lost the port engine again. This is very frustrating. After sitting at the dock for about 90 minutes, she starts up again. Its interesting, as after the engine dies, and I try to start it again, when I turn the ignition, I do not get the tow "buzz" audible. Once it cools off, I turn the key, get the two buzz audible, and I know she will start right up. Any thoughts??
Click to expand...

I am having the same exact issue and have done everything that you have done. What did you do to fix the problem?
 
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