ECM...or something else? Mercruiser EFI 0L916255

lattle4

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Mar 28, 2022
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Hello--Long time lurker, first time poster. I appreciate all the insight I've gotten out of this forum for the last few years. The experience on this forum has pointed me in the right direction almost every time.

I am stumped on this problem however. I bought a new to me 2001 Chap 230 SSI, with the Mercruiser 5.7 EFI serial # 0L916255. Bought from original owner, 350 hours, relatively well maintained, but rarely used. Boat was running fine on test drive, but I could tell it needed a tune up. After purchasing, I decided to do all the probably overdue maintenance. Bellows/Gimbal, Shift cable, impeller, spark plugs, wires, distributor, and fuel filter.

Here's where the problem starts. I started it up on the hose, ran fine. Changed the fuel filter and had to cycle the pump several times to prime it. It took longer than what I thought was "normal" but it eventually primed and ran well. I took it to the river for testing before we towed to the lake, and within just a few minutes at full throttle it stalled out. Listening to the fuel pump, on the start up after stalling, I could tell it wasn't priming. Being stuck on the river, I tried multiple times trying to prime the pump with the 1st ignition cycle....many, many times. It eventually primed, and I made it back to the dock.

When I got home to start troubleshooting, the fuel pump would not energize at all. No priming, and no beep when turning the ignition on to pre start. The gauges work, and the starter will turn over...but obviously won't start. Here's what I've done:

*checked power at pump, nothing coming from the lead.
*checked power pre and post 90 Amp fuse on the starter-- 12v on both sides.
*checked all 3 fuses next to the ECM. All good.
*checked relays-- power is coming to pin 30 on both fuel pump and ignition harness.
*changed relays anyway.
*checked kill switch...all good.
*checked 50 amp red reset...good, not tripped.
*checked battery charge, it is fine and it has a newer battery.

So..now I'm stumped. My understanding is that the oil pressure sensor/switch wires powereing the fuel pump don't apply to the EFI, only carb. Before I send the ECM off to be checked...what am I missing? Is there anonther system that could be causing my issues?
 

dubs283

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Jul 27, 2005
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5,322
Guessing a mefi system?

If so the fuel pump relay gets a signal from the ecm to energize momentarily upon initial key on. Could check continuity between the ecm and relay connection

Would verify good ground for the relay connection as well
 

lattle4

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Mar 28, 2022
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Guessing a mefi system?

If so the fuel pump relay gets a signal from the ecm to energize momentarily upon initial key on. Could check continuity between the ecm and relay connection

Would verify good ground for the relay connection as well
Thanks...I'll give that a try. Yes..it's a MEFI 3
 

Fun Times

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9,046
Just an fyi...0L916255 belongs to your alpha 1.47:1R stern drive unit, not the engine. ;)

Make sure your shift interrupt switch is not activated should an incorrect adjustment occurred somewhere along the way after servicing it all.

The pump and beep is still not sounding even at home?
With key on, just in case, try wiggling the engines main bigger cannon plug wiring harness connector to see if the beep comes back and fuel pump powers back up.

 

lattle4

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Just an fyi...0L916255 belongs to your alpha 1.47:1R stern drive unit, not the engine. ;)

Make sure your shift interrupt switch is not activated should an incorrect adjustment occurred somewhere along the way after servicing it all.

The pump and beep is still not sounding even at home?
With key on, just in case, try wiggling the engines main bigger cannon plug wiring harness connector to see if the beep comes back and fuel pump powers back up.

Thank you...I see now that the serial number belongs to the drive. I have all the original paperwork.

That is correct....I get no beep and no pump at home trying to diagnose. I just went out and tried wiggling the main wiring harness....still nothing. Would the ICM control the fuel pump in any way? It seems like that might be my last thing to check before considering the ECM. My worry is, that during the panic of floating down the Tennessee River trying to get it started, I may have stressed and burned out something while trying to get the pump to prime.
 

lattle4

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Mar 28, 2022
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Well..to follow up, I found my issue. I was about to pull the ECM to send off for diagnostics, when I discovered a tiny ground wire that routed down behind the engine, tagged in with another, had popped loose. I grounded it and voila-- I have the beep and the fuel pump energized. Unfortunately...the fuel pump is SHOT. Sounds horrible, very loud, and eventually just buzzed. I also discovered that my anti-siphon valve was stuck...which is probably what caused the fuel pump to crap out after cycling it so many times.

Luckily...I discovered there is a bracket holding the fuel pump assembly, cool fuel system with the copper tube, attached to the port motor mount and you can just unhook the bracket from the mount and drop the whole assembly. Not easy to get to and I had to remove the exhaust manifold, but it beats removing the engine, which is what I was thinking I had to do!

I've ordered a new pump and pressure regulator. The copper cooling tube looks fine since this is a fresh water boat, so I'm not replacing it. I will put it all back together when the parts arrive. Thanks for helping me brainstorm!
 
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