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5.7L EFI Mercruiser not starting

LukiHarris

New member
Hello, I am having issues starting my 2000 5.7L EFI Mercruiser after replacing the head gaskets.

I have about 180 compression in each cylinder, and I definitely have fuel. It seems as though I’m not getting spark or at least not enough spark. When I turn the key the engine will crank but it will not fire. It does not appear to help if I add any throttle. I’ve had a few sputters and a couple coughs of flame.

The motor was running prior to the gaskets being replaced. I also replaced the thermostat and temp sending unit. I replaced the spark plugs with hope that was my issue, but no luck. I’ve pulled my new plugs and they appear to be already sooty. I’m at a loss right now. Any thoughts?
 
If you verify distributor timing is correct and you in fact do have good ignition spark, you may want to Pull those valve covers and check the lash on the rocker arms.

Zero lash and one turn on the rocker nut is way too much.
 
I was thinking timing as well, but I marked the distributor when I pulled it. If it is off, it should really only be off by a little I would think? Definitely could be lash. I set zero lash and did a half turn but still no luck
 
I was thinking timing as well, but I marked the distributor when I pulled it. If it is off, it should really only be off by a little I would think? Definitely could be lash. I set zero lash and did a half turn but still no luck

At 1/2 turn you should be fine. Rotating the push rod is the wrong way to set rocker arms. Lifting the rocker off the push rod is the correct way.


Pull #1 plug, cover hole with finger, turn engine till you feel the air pushing out of the plug hole, turn crank until timing mark is at TDC, reconfirm distributor timing.
 
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Further Chris... marking the disti does not guarantee that the correct pair of teeth ( disti and cam) are mating. His method is the only way to do it without a special tool.
 
and this "special tool" does exactly what to install a dist correctly?
Once your at TDC with the timing mark lined up you only need a long screwdriver to rotate the oil pump shaft to align it with the dist
 
Timing corrected. Pulled the cap and sure enough that was my problem. Fired right up with a flick of the key!

My next question, what is the optimal running temp for this engine? And will it run hotter with muffs than being fully submerged in water?
 
if you put the 160 deg F t-stat back in and the cooling system is in good shape, it should run ~ 160 deg F.

as long as you dont run out of water, it shouldn't matter if the muffs are used....
 
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