ECM problem .. maybe

[H20HOLIC]

Newbie here with no marine engine expertise, so please be gentle..<br /><br />We have a 1999 Stingray with a Mercruiser 5.0 EFI. Just replaced a cracked block with the help of some friends who have a lot of engine expertise, but not so much in marine engines. All other components seemed fine so we put everything back on .. we of course used new marine gaskets, rings, etc.. Had the starter reworked by marine shop. Started up and ran great, but had to be manually primed first. Sounded like the fuel pump was coming on sometimes, sometimes not. Took it in to have them hook it up. Had a bad coil so replaced that. Now they say the test stops at the computer, but in the same breath they say that if they have to replace it, it will only be the 2nd one they have replaced in 12 years. Other info on the net says these things very rarely go out. <br /><br />Three questions: <br /><br />1. Do any of you think it could be something other than the computer? <br /><br />2. If you think it is the computer, does anyone know a place we can send it for repair? (Our local place hasn't offered that as an option, of course)<br /><br />3. If it can't be repaired, does anyone know where you can buy one used?<br /><br />Thanks for any advice you can offer.

 

[Bondo]

Re: ECM problem .. maybe

I rather Doubt it's the 'puter......<br />What Exactly is the Problem.........<br />You've Recently Moved, Wiggled,+ Possibly Bumped or Mangled All of your Wiring......<br />I'd go back for Another Inspection of Everything that's been Touched, <br />Before I started Throwing Money at It........<br /><br />The Fuel Pump has a Oil Pressure By-pass circuit built into it.... <br />So the engine/fuel Stops if No Oil Pressure is Present.........

 

[H20HOLIC]

Re: ECM problem .. maybe

Forgot something important: The reason we took it in (other than because it had to be primed) is because we stopped being able to crank it, even when we primed it. Did the spark plug test and no fire was getting to the plugs.

 

[Darian F.]

Re: ECM problem .. maybe

if you now have normal spark and the engine runs funny, hook up a fuel pressure gauge and test pressure to see if your problem is fuel related<br />if helps to take readings while underway and at idle

 

[H20HOLIC]

Re: ECM problem .. maybe

I stink at explaining things sometimes, and I think my last post was unclear. <br /><br />The situation right now is this: <br /><br />We picked the boat up from the shop without letting them replace the ECM .. we wanted to research it before putting a hunk of change into it. The engine will turn over but won't crank, even if we prime it. It was cranking before if we manually primed it. Now there is no fire getting to the plugs.<br /><br />We plan to try Bondo's suggestion.<br /><br />Thanks for the replies so far! Keep 'em coming!

 

[outboardguy]

Re: ECM problem .. maybe

Pull off the spark arrestor and crank the engine taking note of whether or not you see the fuel injectors spraying fuel. I'm assuming it's a TBI system and not MPI. My guess is that the sensor in your distributor is broken. The sensor in the distributor is the speed signal for the ECM and if it does not recieve a speed signal it will not spark the plugs or fire the injectors.When replacing the sensor follow the manual and don't try to save the old rotor, just replace it.

 

[outboardguy]

Re: ECM problem .. maybe

Out of curiousity, just how were you priming the fuel system?

 

[arboatdr]

Re: ECM problem .. maybe

If , by chance, it turns out to be the ecu you can send it to CDI in atlanta. I'll have to look up the addy but they have repaired a few for me (outboard ecus) with great sucess and reasonable prices. There tech dept is pretty sharp. Good luck

 

[H20HOLIC]

Re: ECM problem .. maybe

outboardguy, thanks for the info, you have been most helpful. Picking up a sensor and rotor today. We'll see if that works .. To answer your question, we primed it by taking off the flame arrestor and pouring a little fuel directly into the throat of the throttle body.<br /><br />arboatdr, thanks for your info also. If this doesn't work, I may be in touch ..

 

[H20HOLIC]

Re: ECM problem .. maybe

Well, put the new sensor in last night.<br /><br />Still no fire.

 

[rattana]

Re: ECM problem .. maybe

Do you have spark at the plugs?

 

[H20HOLIC]

Re: ECM problem .. maybe

No spark at all.<br /><br />

 

[rattana]

Re: ECM problem .. maybe

Do you have voltage at the coil when the key is in the run position, Also check if you have voltage when the key is in the start position.

 

[H20HOLIC]

Re: ECM problem .. maybe

Don't know about the voltage. Will check tonight. Just replaced the coil (if that matters). Motor spins, but has no fire.<br /><br />Thanks for your help.

 

[llerrad]

Re: ECM problem .. maybe

Is there any other switch or so that can shut off the ele. system. Inerupt switch shift related.

 

[arboatdr]

Re: ECM problem .. maybe

Make sure the hose clamp is tight on the engine harness from the key switch. I've seen bad connections there do strange things. You might want to pull it loose and inspect the pins, maybe bent or need cleaned off. Sounds like you've covered just about everything else.

 

[outboardguy]

Re: ECM problem .. maybe

I'm sorry to hear that the sensor didn't work.Did you check to see if you had injection while cranking like I suggested. That is the only thing I know of that will take out both injection and spark,that is why I suggested it.Hope you find it soon. Good Luck

 

[fireship1]

Re: ECM problem .. maybe

Hello, This engine might have an ignition module. I'm not sure if it does, but if so it is most likely bad. Sometimes EFI engines have an ignition module. It reads the crank/cam sensor and fires the coils. Sometimes the ECM has it built in. If you have the external type it is the last part that could be causing no voltage to the coil.

 

[denniz]

Re: ECM problem .. maybe

Chiming in late as usual, have you tried un hooking the shift interrupt switch and the grey tach lead? both could cause a NO FIRE situation.

 

[H20HOLIC]

Re: ECM problem .. maybe

"Life" has been happening and we haven't had a chance yet to do some of the troubleshooting you guys have suggested. <br /><br />Thank you all very much for your willingness to help.<br /><br />I will defintely keep you updated as we check things out.