Engine cranks but won't start.

[infy]

I'm having some trouble with a 305 Mercruiser on a 1990 Avanti 2955. My observations:

a. The engine cranks at a good rate but there is no sign of ignition.
b. I removed the top of the carburetor to check for gasoline and it seemed wet and I saw fumes rising when applying full throttle.
c. I let it sit with full throttle in case it was flooded. No change. d. The RPM gauge didn't move while cranking. Maybe broken?
e. I thought of advancing throttle while cranking. So I push from N to F but anything past F would kill the starter and the engine would stop cranking until you put the lever back to N. I guess you can't apply throttle while starting?
f. I pumped it between full throttle and full reverse. No change.



Tomorrow I'm going to drop by an auto store and see if I can rent a spark tester.

Just recently the previous owner changed the distributor cap and installed new spark plug wires. He also sent a video of it running after doing that work... and insists that it ran fine. I have no reason to doubt his honesty. It's possible I just flooded it.

The second twin engine starts/runs fine. I'm only having trouble starting the first.

Is there anything else I should try when I'm out there?

 

[Scott Danforth]

welcome aboard.

is this boat new to you, or is the condition new to you?

 

[alldodge]

e. I thought of advancing throttle while cranking. So I push from N to F but anything past F would kill the starter and the engine would stop cranking until you put the lever back to N. I guess you can't apply throttle while starting?

The shifter should have a button at the pivot point which is pushed in or pulled out the disengage the shift cable. Then the throttle handle can be moved forward to pump the carb or give more throttle while cranking.

Do you have 12V at the positive side of the coil?

 

[infy]

welcome aboard.

is this boat new to you, or is the condition new to you?

Thanks. I just bought the boat on Saturday but didn't get a chance to try and start it until last night. It's my first boat but I've worked on my own cars for years.

The shifter should have a button at the pivot point which is pushed in or pulled out the disengage the shift cable. Then the throttle handle can be moved forward to pump the carb or give more throttle while cranking.

Yeah, found that. I'll play with that button and see if it helps. I could move the throttle for both engines, no problem. But if I advance it more than a little forward, the starter is killed. The engine will no longer crank until I put it back at N. Is this a safety feature?

Do you have 12V at the positive side of the coil?

I didn't have my tools with me so I couldn't test it. I'll make sure I have some next time I'm out there.

I also realized I should check the kill switch lanyard.

 

[Scott Danforth]

ok, lets start in the beginning.

just moving the binnacle controls also moves the drive into gear. yes, this is a safety interlock. its the neutral safety switch to prevent you from starting in gear.

you have to dis-engage shifting when starting (button on base of binnacle, or pull handle outward). re-read this line many times until you understand this portion.

think less about cars, and more about a 1960 truck. your boat does not have a fast idle cam, and does require priming the fuel system to start. the lack of a fast idle cam is also a safety issue so when you put the boat in gear, you dont go running swimmers and docks over.

typical carbureted motor starting sequence:
blowers on for 3-5 minutes
dis-engage shifter
2 full pumps (primes the motor and sets the choke), then throttle 1/3 way forward
hit the key
pull the throttle back to about 1500 RPM, let warm up for a few minutes (remember, no fast idle cam)
pull throttle back to neutral to re-engage the shifter
go boating

 

[harleyman1975]

Tach not moving and P.O. having just worked on that engines ignition system leads me to believe the problem existed before you bought it. I would start by trouble shooting ignition on that engine.

 

[infy]

ok, lets start in the beginning.

just moving the binnacle controls also moves the drive into gear. yes, this is a safety interlock. its the neutral safety switch to prevent you from starting in gear.

you have to dis-engage shifting when starting (button on base of binnacle, or pull handle outward). re-read this line many times until you understand this portion.

think less about cars, and more about a 1960 truck. your boat does not have a fast idle cam, and does require priming the fuel system to start. the lack of a fast idle cam is also a safety issue so when you put the boat in gear, you dont go running swimmers and docks over.

typical carbureted motor starting sequence:
blowers on for 3-5 minutes
dis-engage shifter
2 full pumps (primes the motor and sets the choke), then throttle 1/3 way forward
hit the key
pull the throttle back to about 1500 RPM, let warm up for a few minutes (remember, no fast idle cam)
pull throttle back to neutral to re-engage the shifter
go boating

That is exactly what I needed. I also remember switches on the side of the throttle handles. I wonder if thats what I'm looking for.

I've got a local mechanic joining me out there tomorrow. He's worked on it before and will give me a tour. I need to be ready to restart this thing on the water and feel good about it before moving to closer moorage.

 

[Corian35]

A dock neighbor had a similar issue on the same boat. Ended up being the condenser inside the dist. cap. also might want to check the gap on the points while you have the cap off.

 

[Scott Danforth]

That is exactly what I needed. I also remember switches on the side of the throttle handles. I wonder if thats what I'm looking for.

I've got a local mechanic joining me out there tomorrow. He's worked on it before and will give me a tour. I need to be ready to restart this thing on the water and feel good about it before moving to closer moorage.

the switches on teh side are the trim. look at the pivot of the handle

A dock neighbor had a similar issue on the same boat. Ended up being the condenser inside the dist. cap. also might want to check the gap on the points while you have the cap off.

the OP's is a 1990 with TBIV ignition. no condensor or points.