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Engine diagnostic basics

chris777

New member
"hey folks, i thought i would

"hey folks, i thought i would share todays experiance with my friends 470 mercruiser (Four Winns)bowrider.

so the story goes, he bought this POS boat late last year,(well trashed $700 boat) we just got it running 3 weekends ago,(ran but not well) overheating,high end miss,hard starting.

(last weekend)i fugured i'd dial in the points and ingnition timing,replace the impeller and see what happens. we replaced the impeller,and also changed the oil(outdrive and engine) but now the boat wouldnt run well enough to get the ingnition system dialed in,(dwell meter/timing light-engine running) so we pulled the carb (seemed to be flooding excessively) and had it rebuilt ($ 113). so (this weekend) i fugure we would slap the wheels back on the trailer (also did the wheel bearings), pull it out of the garage,stab the rebuilt carb on her, hook up the hose, and get at the ingnition system. the thing just would not run. so i checked the points with a feeler guage (they were ok),checked the ingnition timing,it was close(i dialed it in), it still would not run, i disconnected the fuel line from the carb,so i could run it on starting fluid only,(it still seemed to be getting too much fuel)STILL wouldnt run. i then replaced the coil with a good one i had, NO GO, i disconnected the condensor,STILL NO. i checked the compression on 1/2/3(couldnt get at 4 with my guage) 110-115-115.should run right?(it had SPARK/COMPRESSION/FUEL) WRONG. i then dug through my spare parts and found a used condensor off my 55' ford tractor, thru it inn and SHIZAM, runs like "PERFECT"
who would of thunk it ,,"
 
"Good work.. yea.. and some cu

"Good work.. yea.. and some customers why it takes so long to work on their over 10 year old boat and why some marina/boat repair places wont work on such aged stuff... Where I work"ed" we had a Frankenstein peice that you can test points, condensors, rotors, coils.. very kool and dangerous.

The overheating issue could be rusted up manifold or sticking thermostat or rusted thermostat housing.(I forget what that one looks like so I could be mistaken)

Also carb flooding could be ruptured diaphram in the fuel pump which you'd either need to replace the entire pump or just the diaphram.(if it's still happening.)"
 
"the impeller fixed the overhe

"the impeller fixed the overheating, the carb is fine now after the rebuild/condensor replacement.
the boat runs out very very good while the only related need is a shifter cable/or luberication."
 
""found a used condensor o

""found a used condensor off my 55' ford tractor, thru it inn and SHIZAM, runs like "PERFECT"
who would of thunk it ,,"

Very common overlooked ignition killer."
 
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