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5.0 EFI No Start Guidance

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mhcrra1

New member
Hi All, first post. I know there are a million ways to go here but I'm looking for anyone to "point me in the right direction".
Have a 2000 Sea Ray Sundancer 290 with twin Mercruiser 5.0 EFIs in her (new to me this year). LONGGGGGGGG story but I pulled motors to change both oil pans/gaskets, fuel coolers, timing chain covers, plugs, fuel filters, etc. etc. Both motors ran beautifully after the service. Had it out for a couple of spins......last one yesterday about a 30-40 minute cruise at 30 knots all seemed great. Docked, went and had lunch.....came back to the boat, STBD motor fired up great, port cranked and cranked and cranked. Checked oil, that was ok.......checked everything basic we could while at the dock and found nothing.....kept trying it over and over and no fire. Limped back to port on one motor and called it a night.

I am a decent mechanic, but not overly versed in Mercruisers so looking for any ideas at all where to start.

It really sound like it's not getting spark.....almost like there is a safety cutoff somewhere that's activated. Everything appears to be in tact visually.....the only thing that's not connected is the gear oil monitor but that has had a broken terminal all summer and never given any fits.

HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:) Rob
 
likely to be missing spark or fuel.....so get a pressure gauge or a spark tester and make the determination on what's missing.....
 
makomark said:
likely to be missing spark or fuel.....so get a pressure gauge or a spark tester and make the determination on what's missing.....
Click to expand...

I have both and spark is obvious to test.....is there a built in schrader valve for the fuel pressure test already in the system??? Thank you for the tips.
 
mhcrra1 said:
I have both and spark is obvious to test.....is there a built in schrader valve for the fuel pressure test already in the system??? Thank you for the tips.
Click to expand...

Just happened to think......possibly be the fuel pump??? I did have the fuel system all apart to change the cooler logs.....maybe pump died or possibly came unplugged???? Hmmmmmmm, guess I should check that shouldn't I?
 
So I went down to the boat tonight top do some diagnostics....hit the switch and she fired up in about half a second. Ran it for a while and she purred like a kitten.
Shut it down and it fired up again no problem
Any thoughts as to what the heck could've happened????
 
my venture at a guess is one of the connectors removed during one of the recent service actions wasn't fully mated....and while the boat sat, the environment changed enough for the connection to go from marginal to serviceable....maybe the wiggle test is in order?

On the schrader valves - the mutiport systems with a rail usually have them....the TBI units normally don't....but they were pretty much obsolete when your boat was built...
 
makomark said:
my venture at a guess is one of the connectors removed during one of the recent service actions wasn't fully mated....and while the boat sat, the environment changed enough for the connection to go from marginal to serviceable....maybe the wiggle test is in order?

On the schrader valves - the mutiport systems with a rail usually have them....the TBI units normally don't....but they were pretty much obsolete when your boat was built...
Click to expand...


Good thought for sure.....I will give it a try!
 
Does anyone think it could possibly be the ignition coil? I have had some people come up with that theory.....saying when they heat up it can break the coil inside and when it cools down they make contact again......engine builder (automotive) friends.....sounds plausible to me.
 
I know of several poster here that have had issues with the interconnects on the EST ignitions....most things are possible on a 20 year old system...especially if the maintenance has been neglected.....
 
A little more info and updates:
went to the boat this weekend, it fired right up and ran perfectly. Cruised around on Friday for a couple of hours at about 2k rpm just putting around not on plane and everything was great.
Slow putted today for about an hour and a half a 1500 rpm and no troubles......came up on plane and ran about 3500 rpm for about 20 mins heading in, ran great. Slowed down and putted through the islands a bit and port motor shut down on its own....waited 60 seconds and tried to start it, vroom...fired up and ran for about 5 mins headed back to dock then it died again. Tried numerous times to start it on the way in and no dice.....just crank and crank. Docked, got things settled...tried it, no go. Pulled covers off and cranked...no fuel coming out of the throttle body injectors. I can hear the fuel pump cycle when I hit the switch like normal, but the throttle body is bone dry. I don’t know what exactly controls the injectors but there is something not telling them to fire I suspect......
does this give us any more clues???
 
If the ECM does NOT get the reference pulses from the distributor, it will turn off the injectors....if this happens, it could be the pickup coil in the distributor or it could be the module, or the interconnecting wiring......you will also loose spark....
 
Intermittent problems are the worst! However, you know that the ignition system is good and that every now and then the fuel delivery konks out. I would be looking at wiring, and specifically at the fuses and the main connectors associated with the fuel pumps. Also as Mark references, the amplifier module.
 
Just wanted to update everyone in case they run into this problem. Changed out the port engine ignition module (the one in the distributor) and after a few weekends of all sorts of running conditions the engine hasn't even shown a sign of a hiccup so I think that solved the problem.
Thanks everyone for the helpful suggestions!
 
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