454 Alpha hard to start, dies at slow speed
 

I have a freshly rebuilt 454 in my 87 Force. Currently, I have 7 hours of break-in time on it. I am having problems getting it started. I have searched and it seems this a fairly common issue with these older 454 with Quadrajets. I have to crank, pump, crank, pump a bunch to get her started. After it starts, it runs well. It will even idle fine around the 500rpm mark. However, it seems to want to die when I shift just out of neutral and into forward. Not when I am getting underway with a little more throttle but during times I am trying to dock or trailer. After it dies, it is a pain to get it to start again. As you can imagine this makes getting it on the trailer no fun. Once running, its super smooth and runs great out on the water. I am still breaking it in so for the first 5 hours I have varied the RPM from about 2500-3000. This last hour or two I have hit 3500 once and 4000 once for maybe 30 seconds. I really am holding back until I get to the 10-hour mark. Anyways, does anyone have any ideas on what might be going on? I am thinking it's a fuel issue. The carb was just rebuilt when I had the motor done. here is what I had done to my old block, carb and outdrive:

• block bore .070
• valve job (ex valves, valve seats, HP valve springs)
• cam bearings
• VAT block
• HP rod bearings
• HP main bearings
• marine head set
• check align bore (ok)
• replace brass freeze plugs
• pressure check ex manifolds
• marine conversion set gen IV
• comp cam xe268-1 224/230 @ .050/.515/.520 "nitrided"
• replace the crank, grind crank rods .010
• balance assembly
• hyd lifters
• true roller chain set w/ thrust
• .070 SRP flat top pistons
• molly rings
• HV oil pump
• oil pump pick up
• sleeve 2 cyl's
• repair damaged starter bolt hole
• replace ring gear
• break in oil
• oil filter
• oil cooler
• oil line
• exhaust gasket
• elbow gasket
• alternator
• starter
• spark plugs
• carb kit
• plug wires
• water pump
• thermostat w/gasket
• new cap and rotor
• bellows boot
• gimbal bearing
• gas line
• impeller
• bearing

TIA for your help!

Pump, crank, pump crank sounds like a carb problem, not all carb rebuilds are the same!
Dyeing from idle to in gear, at 500 rpm the Alpha drive has a spark (ignition) interrupter on the shift plate assembly, at that low of an rpm it may not have enough to recover, try setting the idle about 750 and see if that helps, also do your shift quickly not slow as that prolongs the timeframe with no spark to motor.
Good luck.

If you still have issues after turning the idle up, look at the lower shift cable. They get sticky after a few years and can cause the stalling issue.. but. 500 rpm idle is definitely too low

I will look into figuring out how to set idle on the carb. I remember talking with my installer about the shift cable but can't remember if we replaced it or not. I will look over my paperwork and see.

The internet and youtube are your friends.

Had this problem with the alpha on my Scarab a few years ago after i installed a brand new 350 MAG MPI. Found the issue to be the shift shaft bushing in the bell housing had begun to corrode and caused just enough drag to cause the engine to stall due to the shift interrupter. Drove me nuts for months I had replaced all the cables and went round and round until i figured it out. It made docking a pain in the ass

Make the shifts abruptly, move the shift lever with intention. And always below 800 rpm

With the assumption there are two idle jets at front of carb..I would adjust those at dockside or on trailer...you can use a tach, vacuum gauge or listen by ear. Then set idle...I run my smallblocks close to 500rpm to help with shifting. Not sure about starting hard..but may be a culprit for poor idle.
A sticky lower shift cable will cause the momentary kill switch not to work effectively (surprisingly)- not sure that would kill the engine.

Absolutely agree about shifting into gear with authority. Don't go slowly and allow the gears to ratchet, that's wear.

You may be able to rule out the sticking shifter issue by testing with one side of the shift interrupt unplugged. See how the engine goes INTO forward without the interrupt. If it stalls and stumbles the issue is probably in the engine compartment. You'll then have to shut off the engine or reconnect the interrupt to get it back out of gear, so plan accordingly. Maybe while tied up or out in open water.

It should not come out of gear unless the interrupt is working.

I demonstrated this to myself the other week when I was out riding and I couldn't get neutral.
With a low idle I had backed my boat up, gone into forward, gone off through the no wake zone, and headed out. Later, while slow running I had turned up my idle to a correct in-gear rpm and then the drive wouldn't go to neutral.
I had taken off my shift interrupt for something else and hadn't plugged it back in. Oops, plugged it in, and all was well.