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5.7L No Spark No Start

gverb1219

gverb1219

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2003 Volvo Penta 5.7L Gi-A...long block replaced in 2017.........was running great...up on plane......slowly started losing RPMs (over 4 minutes) went from 3,400 rpm down to 700 rpm then died.....will not restart.

Tested all ignition components....tested good....replaced anyway. 12.6v feeding coil.
Retested all ignition components...all test showed good.

Timing marks spot on with #1 at TDC. Cap and Rotor replaced, ICM replaced, Ignition Pick-up Coil replaced, Ignition Coil replaced, TBI Injectors working, New Fuel Pump working fine, Fuel Filters replaced, Wires replaced, ground wires cleaned and secured, compression good.....VERY WEAK to no spark from coil post ...still no start..only thing hasn't been changed out is the ECM.........
I am lost and have no other ideas what to try.

I have a full set of Volvo Penta Workshop Manuals given to me by a former Volvo mechanic....did all the troubleshooting tests....I still can't figure it out......

My boat is on my lift in my canal so I can't get it to a shop for a full ECM scan and can't find anyone who does house calls.....

I did a DTC and got a code #44....but I think that was from disconnecting the knock sensor during my trouble shootinig.....

Any help would be appreciated
 
I'd agree the DTC44 is likely due to disconnecting the knock sensor with the engine running....

The ECU has little to do with the quality of the spark the coil produces.....but, on a 2003, should control the timing advance.

I'd suspect the issue isn't within the parts you have changed, but in something you haven't - bad wire, wire termination, or connector housing are the likely suspects.
 
makomark said:
I'd agree the DTC44 is likely due to disconnecting the knock sensor with the engine running....

The ECU has little to do with the quality of the spark the coil produces.....but, on a 2003, should control the timing advance.

I'd suspect the issue isn't within the parts you have changed, but in something you haven't - bad wire, wire termination, or connector housing are the likely suspects.
Click to expand...



That's kinda where I'm starting to lean.

I charged the batteries and checked the voltage going into the coil....12.58v, however when I crank the endine the voltage plug feeding the coil drops to around 7.8v to 8.3v.

I plugged the harness back into the coil and pulled the 2 wire harness off the distributor. Got a reading or 12.46 at the plug.....cranked the engine over and voltage dropped to almost the same....8.4v to 8.7v.

Not sure if it should drop that much with the engine cranking......don't know what a "normal" voltage drop while cranking is.....
 
Sounds like an excessive voltage drop.....I'd check the voltage at the starter when cranking...if that's ok, check for a large voltage drop in the ground cable, between the block and the NEG terminal on the battery....relays are suspect if on that model....the main harness connector is another potential trouble spot...
 
makomark said:
Sounds like an excessive voltage drop.....I'd check the voltage at the starter when cranking...if that's ok, check for a large voltage drop in the ground cable, between the block and the NEG terminal on the battery....relays are suspect if on that model....the main harness connector is another potential trouble spot...
Click to expand...


.....if you're referring to the 2 relays....ignition and fuel pump mounted next to the TBI......they are both working. Fuel pump is coming on for 3 seconds and injectors are pulsing fuel when cranking.

I think I'm going to end up pulling the wiring harness off and doing a continuity test on every wire.....don't want to, but don't know what else to try. Also going to pull the ground wires off block again and check them all.
Battery cables appear good, I just replaced the starting battery last month. I might pull both batteries out and give them a good charge because cranking the last couple days is wearing them down even though I have a trickle charger on them.
I am so lost on this issue I'm pulling my hair out.....never took this long for me to get an engine running......f-ing ECM controlled engines suk.....lol
 
If you haven't verified the voltage drop across the relays as acceptable, how can you declare it 'working'? Just because the electromagnetic makes the 'click' doesn't mean the contacts will pass their rated current.....same for battery cables. if you want to continuity test every wire, go right ahead....as far as starting currents go, its not time well spent....
 
makomark said:
If you haven't verified the voltage drop across the relays as acceptable, how can you declare it 'working'? Just because the electromagnetic makes the 'click' doesn't mean the contacts will pass their rated current.....same for battery cables. if you want to continuity test every wire, go right ahead....as far as starting currents go, its not time well spent....
Click to expand...

I only said it is working in referring to pump comes on and injectors spray when cranking the engine.
I'm not sure where to measure voltage drops in the relays. I looked in the book and it only talked about those 2 relays if the fuel pump isn't working to try replacing with good relays... and it is working and injectors spray when cranking.
If I'm missing something here, please tell me where to check for voltage drop because the book doesn't say (at least I didn't see it).
I hope I'm not being pushy....I'm just lost and following the troubleshooting section for "Engine cranks, won't start".....batteries are out and charging......this afternoon when I put them back in, I'll try to check cranking voltage at the relays.........thanks
 
Take the plugs out at the ecm and verify all blacks( I think 3 in all) go to earth, do this using a test light from the black back to a 12v pos, not using a multimeter. It would appear you have a bad earth since you do have a weak spark. You also need more than 10v whilst cranking.
 
New Fuel Pump working fine,

Does that mean you have 41 psi at the fuel rail? Unless you have x-ray vision you cant see the spray pattern inside the intake manifold. you should have a low pressure boost pump and a high pressure pump, both need to work to run the engine
 
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