HELP, ECM Fail or something else ?

[Regal_2250]

2005 regal 2250
5.0 MPI 300 hours (saltwatercool)
Serial# 0W326550
ECM# 865926 Motorolla I believe they call this the 555.

It's a new to me boat. I ran it once and performance was sluggish. I ran it a second time and the fuel pump would not come on and I went adrift. Boat would not start. A friend helped comb through some checks:

Put 12 v to fuel pump through relay and pump is fine.
Verify kill switch - ok
Check voltage to relay - ok
Put Jumper wire to relay ground and touch off ground on engine and relay is clicking.
Apparent not getting ground supply from ECM.

If you turn the key to the ON position, the fuel pump will not start. If you leave the key ON for 15 or 20 minutes, the fuel pump will randomly start and continues to work until boat is left off for some time.
I got another tech with diacom to assist and scan. Engine would not communicate from ECM and would not read data. At this time the fuel pump would also not start. Tech does other checks and 1hour later he leaves. I go in the boat turn the key and the fuel pump starts and he comes back. Hooks up the computer and it reads. NO codes. Determined that the MAP sensor is showing a default value and is inevitably toast hence the poor performance. I ordered it. I brought the boat to him 2 weeks ago and looks like he hasn't touched it yet...getting anxious. Hoping to put my ecm in another 5.0 and see if the problem moves but so far it hasn't happened.

Now. What's up with the ECM? I can have it sent to Whipple for 850usd, I can send it to Simon motorsports for 675usd or Boats Unlimited for a split between 650 and 975usd. Firstly I am unsure yet if the ECM has failed but Bob at ODB I Fresno says it's likely my fuel pump driver has failed and this is common. John at Boats unlimited says they don't fail on their own and either a voltage issue or a short in the harness. Anyone have any experience with any of these companies ?
What do I do? I am desperate for any advice my season is slipping between my fingers here and I'm in near 30K on a new to me lawn ornament that I told the wife was going to be reliable and safer for the family.. pretty disappointed.

Help please

Thanks.

 

[1000 Islands]

I can't imagine a failed fuel pump driver would cause the loss of communication with the ECM. If a faulty MAP sensor is taking down the 5v ref, just unplug it when the problem is occurring to see if the communication is restored. In theory, anything corrupt with a 5v ref can cause big problems for the ECM, but it's not usually fatal for the ECM.

If you have the skill set, and a wiring diagram, load test all of the B+ and switched B+ to the ECM using a test halogen fog light bulb. You need something that will draw current, not just a continuity tester. Same for all of the grounds. And you can even do the same for the fuel pump relay control circuit. This is not easy work. But IMO, you have to check all of the power circuits and all of the ground circuits properly before even considering condemning the ECM.

 

[Regal_2250]

I can't imagine a failed fuel pump driver would cause the loss of communication with the ECM. If a faulty MAP sensor is taking down the 5v ref, just unplug it when the problem is occurring to see if the communication is restored. In theory, anything corrupt with a 5v ref can cause big problems for the ECM, but it's not usually fatal for the ECM.

If you have the skill set, and a wiring diagram, load test all of the B+ and switched B+ to the ECM using a test halogen fog light bulb. You need something that will draw current, not just a continuity tester. Same for all of the grounds. And you can even do the same for the fuel pump relay control circuit. This is not easy work. But IMO, you have to check all of the power circuits and all of the ground circuits properly before even considering condemning the ECM.

This certainly exceeds my capacity however I have a couple of talented resources and I do understand the language. I'm glad I have been able to paint somewhat of a picture to convey what's going on because your response makes alot of sense. When I started to consider removing the ECM and just sending it out for the assessment/repair, I too started to question if that was the correct response given that I am getting no communication ti the ECM. Sadly i think I've been sold a lemon and a wiring issue ghost ship and I'm completely shattered. Really don't know where to turn. Hoping my technician can pull an Ace out and give me some answers. Thanks so much for your recommendations I will be sure to pass them along.

Meanwhile if anyone out there has any further suggestions I welcome each and every one of them. Thanks so much.

 

[Regal_2250]

I can't imagine a failed fuel pump driver would cause the loss of communication with the ECM. If a faulty MAP sensor is taking down the 5v ref, just unplug it when the problem is occurring to see if the communication is restored. In theory, anything corrupt with a 5v ref can cause big problems for the ECM, but it's not usually fatal for the ECM.

If you have the skill set, and a wiring diagram, load test all of the B+ and switched B+ to the ECM using a test halogen fog light bulb. You need something that will draw current, not just a continuity tester. Same for all of the grounds. And you can even do the same for the fuel pump relay control circuit. This is not easy work. But IMO, you have to check all of the power circuits and all of the ground circuits properly before even considering condemning the ECM.

Also of anyone can point me to an online resource that would contain my wiring diagrams I would be eternally grateful.

 

[1000 Islands]

Other than guessing, this is a difficult task to diagnose your problem. I bet there is a lot of low-hanging fruit at your marina, and the hard stuff gets pushed to the back burner. I also bet that this was an ongoing issue and the previous owner dumped the boat. It's gets resold, and here you are. Is the tech you are dealing with doing this on the side, or at a marina? Are used ECM's available somewhere? I wonder if they are plug-n-play?

 

[alldodge]

I'll put it this way, Bob will not steer you wrong and John is one of the best at finding and fixing the faults. As for the others you mentioned, I would only go to them if Bob or John were unavailable and time was the issue

 

[1000 Islands]

Holy smokes 555's are expensive USED!

*IF* the driver indeed has failed and IF they don't fail on their own, that would only leave a short to power as the killer on board. If the driver is a common failure, is there a common place to look for short to power in the harness??

Since the fuel pump is controlled by a relay, and the driver is on the primary side, the ECM won't see anything on the secondary side, including the fuel pump. In the automotive world (yeah, I know..) a driver is usually murdered by a short in the device it's controlling, aka an ignition coil, a solenoid, etc. And in my experience, a driver either works or it doesn't. I don't recall ever running into an intermittent one.

I still don't see the connection between a failed driver and no ECM communication. Again, check your B+'s and grounds, and maybe even unplug the ECM connectors and look for trouble there.

Or bring the entire boat to a marina with a good tech who isn't afraid to role his sleeves up. Good luck.