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5.7L v8 with AlphaOne shutting down when little throttle is applied

First test it on muffs (dont go more than idle!): if it stalls its your lower shift cable sticking - needs to be replaced

If its fine on muffs (no prop load) lower cable is prob ok.

Test on water - if it stalls now your shift interrupt switch is "over" compensating - OR you are shifting too slow (but most likely the switch). Its either sticking (ctting out the motor too long) OR the metal pin with roller is bent toward the V TOO MUCH - it should have about 1/8" play before the switch grounds (yours might be the volvo style with just a little tip - if so you dont bend the pin like below but adjust it).

Way to test switch is with motor not running, connect multimeter to both sides of the switch (one is ground and another runs to ignition primary). Either way if you can disconnect both (either at switch or elsewhere - whatever is easier). Connect multimeter to both pins - and operate switch and see when/where it beeps/closes. ITs a NO type - "normally open" - it should only "beep" (kill motor) after a little bit of movement from the V it sits in. It should also be in the middle of the V.
 
it will start and idle on muffs till you throttle up a little. if you hammer down the throttle it will get to High rpm. only dies if you try to give a little throttle,warm or cold.
 
its def your shift interrupt switch adjustment. when last did u do the lower shift cable? The switch gets "activated" via the lower shift cable: EITHER on prop load (normal use) OR if the lower shift cable is sticky (abnormal).

If the switch is out of adjustment it will either engage the kill period for too long (total stall) or not at all (grinding gears / stuck in Fwd/Rev and hard to go into gear).

So you have either:
Sticky lower shift cable (prolongs the kill duration by imitating a shifting condition - ie putting load on the shift bracket where the big switch sits)
Out of adjustment interrupt switch (too close to the V and killing the ignition for too long as well).

Usually a faulty switch adjustment will only show up on water as it requires gear load via the prop. Any other shifting problem is either related to a sticky cable OR switch adjustment or both.
 
This is just how I roll, buut I would never take a "new to me" boat out until I have done:
A full tune up to include cap rotor points condensor wires plugs timing adjust carb adjust.
Check all cables for smooth operation, connection, corrosion. Shift adjustment.
Oil change new filter. Fuel/water separator filter. Check fuel hoses and tank for crud.
Cooling system hoses and hose clamps. New water pump impeller, check circulating pump for wobbly bearing and weep hole. new belts.
Change oil in drive. Top up trim pump. Check trim for operation.
Check electrical connections for tightness and corrosion. Dielectric grease in main harness connector. check all fuses.
Turn steering lock to lock. Top up power steering fluid.
Make sure bilge pump operating properly.
Ditto bilge blower.
Lights and horn working.
New batteries.
Engine mounts and stringers for corrosion. Clean and grease.
If all that passes, the boat should be good to go. Always tell someone on shore when you are going out and when you expect to be back. If you know tell them where you expect to be.
Wear you PFD if you are the only one on the boat. OK wear it anyway even if you aren't. If you can't stand the bulk, get the auto-inflating Mustang one. Yes it costs but I would guess that given a choice between spending 275 or treading water until you drown that you'd spend the 275. Also, if you are going out solo, get the autotether thing that kills the engine if you fall overboard.
 
Before doing all that, pull the flame arrestor and eyeball down inside the carb (choke held open) as someone works the throttle (engine OFF). You should see a stream of gas squirting out and down the barrels. That's called the accelerator pump, and they tend to get gooked up after sitting.

If yours doesn't squirt, remove the throttle linkage and work HELL out of it until it starts working again.

Jeff
 
Does not sound like the shift cable. No roller on your shift interrupt either.

Sounds like you have an accelerator pump issue in the carb.

Sorry Jeff didn't see your post.
 
fastjeff said:
Before doing all that, pull the flame arrestor and eyeball down inside the carb (choke held open) as someone works the throttle (engine OFF). You should see a stream of gas squirting out and down the barrels. That's called the accelerator pump, and they tend to get gooked up after sitting.

If yours doesn't squirt, remove the throttle linkage and work HELL out of it until it starts working again.

Jeff
Click to expand...

Further Jeff's post... When that engine was built it was painted after it was assembled. This resulted in paint getting on everything including the link between the throttle and the accelerator pump. This paint formed a "zero clearance" bearing so there was no slop or lost motion when the throttle was opened and the accelerator pump shaft moved. With time or after a rebuild, this paint is chipped off and results in "slop" in the link to the accelerator pump. This slop allows the throttle to open BEFORE the accelerator pump shaft moves ( and squirts gas)... Creative rebending of the wire link between the throttle and the accelerator pump can eliminate this slop. I had this issue, drove me nuts for a whole season. Someone on this forum (sorry I forgot who) pointed out that the z like bend in the wire link is intentional to allow just such an adjustment. You need to "flatten" the z just a bit in order to lengthen the overall link a bit to take out all the slop in the "actuate accelerator pump" direction.
 
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