Mercury 2.5 200 Starting Issue

[rankink]

2.5 92 block with wh20 carbs, lightweight flywheel, 140 psi heads, 7 pedal reeds, fuel pump at 5.5-6 psi.


I have done as much as I can with the current problem, so turning to others for help. History is the engine ran fine for a couple of days, and then just cut off while at about 4500 rpm. Would not start right away due to starter going out. New starter installed and have not been able to fire up. The engine just spins but will not fire up at all. Backfires out of the exhaust/prop.


Things checked below:
New stator
New trigger
new switch boxes
Rebuilt carbs (wh 20)
Choke/enricher working
Fuel pump working and carbs getting fuel
Timing OK at 25 btdc
Spark checked on all plugs, and new plugs
Compression has not been check yet, but heads pulled with no issues
Grounds checked
Battery charged
Tried starting with remote harness to confirm it is not kill switch
Gas is OK
checked vacuum tubes

Any help would be greatly appreciated

[gorillapowered]

Did you check the reeds?

[rankink]

Yes I did while the carbs were off with no real issues.

[CircleHook]

You pulled the heads with out checking compression first?
OK you got spark and timing appears correct
You think you have fuel (are plugs wet?) Could you have lost vacuum somewhere? like pulse fuel pump hose/port? I don't think bleeder line would cause this
third part of this equation is compression Do a Forest Gump check and see what compression is
Magnets in flywheel cracked?

[perfmarine1]

Your first check should always be compression check,then spark,if they both check ok then it has to be fuel or timing way off. Spark check needs to be done with a good spark check tool,you need spark to jump 3/8 gap with blueish white color with good snapping sound.