84' mcm228 305 gmc won't start

[MICHAEL28]

Re: 84' mcm228 305 gmc won't start

I had an issue like this before and it was the momentary kill switch that is part of the "shift cable rocker" deal, sorry I don't know proper terminology but there is a kill switch there to stop spark when you shift into drive and mine was stuck. Also it is not recommended to use a regular coil because that thunderbolt doesn't actually advance the timing, it increases and decreases spark based on engine speed determined by the magnetic pick-up in the distributor.

 

[MikDee]

Re: 84' mcm228 305 gmc won't start

Has this engine ever run for you before? What is it's history? I still think it's out of time. When you are setting #1, do you feel compression building in the cylinder with your finger, if not then the camshaft is set to fire on #6, with having both cylinders at TDC at the same time, all the time because that's the way the crank is made. Then you would have to take out the distributor, give the rotor 1/2 turn, and put it back in, so the distrbutor rotor is facing #6, to match the cam's firing position.

 

[Reel Poor]

Re: 84' mcm228 305 gmc won't start

It has fuel, fire, and compression then my guess is the timing is retarded. Loose the timing light and the pre timing practice. While trying to start the engine slightly advance the timing (turn distributor counter clockwise). Once you get it cranked then set the timing with the light.

 

[firetrk]

Re: 84' mcm228 305 gmc won't start

Michael28,
The switch is called the shift interrupt and I tested this switch already. It is working properly.

MikDee,
The boat was in full working order then pulled out of the lake and winterized. The owner got sick and then later died. The boat was covered and untouched from it's winterization for at least 7 years. I have static timed the engine several times and yes, cylinder #1 was on compression stroke.

Reel Poor,
I have done and just did again today what you suggested. Still nothing. When I hit "the sweet spot" the motor catches and acts like it's about ready to start but still won't. I have used starting fluid to see if it is a lack of fuel and the results are unchanged. I too believe it has something to do with timing and spark. I am still under the impression that the pickup isn't working correctly. I checked the cap and rotor to make sure they are for this engine and everything is correct. Starting to get real frustrated with this thing...

 

[dubs283]

Re: 84' mcm228 305 gmc won't start

when you say pickup do you mean the ignition sensor in the distributor? should be black plastic with white/green, white/red, and black wires.
The ground (black wire) should be grounded to the same ground on the motor the battery is attached to. bell hsg stud at back of motor

ignition amplifier? do you mean ignition module? mounted on the port side exhaust riser?

 

[Bifflefan]

Re: 84' mcm228 305 gmc won't start

Just because im cerious, is the dist. the one with the big cap and and the coil inside the cap?
if so there is a large wire going to the cap marked Batt on the top of the cap. run a new wire 12+ volts to it from the batt. and then try to fire it. this will bypass any safety switches that are installed. also'

To turn off the motor you must disconect the wire to dist.

Doing this will let you verify that the motor will run.

 

[firetrk]

Re: 84' mcm228 305 gmc won't start

Just because im cerious, is the dist. the one with the big cap and and the coil inside the cap?
if so there is a large wire going to the cap marked Batt on the top of the cap. run a new wire 12+ volts to it from the batt. and then try to fire it. this will bypass any safety switches that are installed. also'

To turn off the motor you must disconect the wire to dist.

Doing this will let you verify that the motor will run.

Bifflefan,
No this has a normal 80's cap, rotor and sensor (sensor in place of points), seperate coil and seperate igniiton amplifier (or ICM).

Dubs,
Yes the terminology is I used is from the 80's. The pickup=ignition sensor and ignition amplifier=ICM or ignition control module.

 

[dubs283]

Re: 84' mcm228 305 gmc won't start

remove the coil wire from the coil and install a simple spark tester, many are available, the best are encased in glass. clip the other end to a good ground and turn the engine over. you should get a rapid "snap snap snap" at the tester with a good strong blue spark.

this way you know you have good ignition, if this is the case one of the following problems is the culprit

-the distributor is 180 degrees off, you say it isn't but this boat sat for seven years, although the folks you bought it from say nobody has touched it, even i have a tough time remembering seven years ago, anything is possible

-there is water in the fuel or the fuel is bad or there is a fuel delivery problem. pour gas directly into the carb through the float bowl vent tube located on top of the carb, centerline near the choke plate, approx 5/16" diameter tube and attempt to start, if the motor fires and runs momentarily, it is a fuel problem.

-there is a compression issue, i have not read that you tested compression yet so you should do this to rule out the possibility

try these tests and you should really narrow down the issue

good luck!!

 

[MikDee]

Re: 84' mcm228 305 gmc won't start

As a WAG (wild eyed guess) is it possible the wire coming from the starter to the coil is for Start only if so, it normally goes dead when you release the spring loaded key switch? and there should be another wire from the ignition switch that delivers 12volts with the key on, (ignition on/off) for Run

 

[firetrk]

Re: 84' mcm228 305 gmc won't start

Just an FYI..the boat still isn't running. Anymore suggestions?

 

[VMAX]

Re: 84' mcm228 305 gmc won't start

It's hard to tell without seeing the boat, but here are a few things that I would check.
#1 Strong blue spark from the coil wire? If so, then check for strong spark at a few different plug wires, pulled off plugs, and a spark tester installed. If one isn't available, put a screwdriver in the metal terminal and hold about 3/8" from the block while someone is cranking the engine.
#2 Advance the distributor by hand while the engine is "almost starting" it should either start, or labor from over-advanced ignition timing.
#3 Make sure that the choke butterfly is wide open, and hold the throttle wide open while cranking if you suspect flooding. Be ready to throttle back immediately if it starts.