1984 seaswirl will not idle after 30 min

[Will6508]

I have a 1984 Seaswirl with a 3.8 OMC engine. The problem began on the very first trip of the year and I have been throwing money at it but cannot get it working. The boat starts and runs fine for the first 20 or 30 min of the day. After that time if you pull it back to idle it dies immediatly. It is hard starting after that but I can usually get it started about mid throttle and as long as I dont come back to idle it will run smoothly. I have changed the points, re-built the carb, change all filters and fluids, and spark plugs. I really figured it would be a carb issue but having it rebuilt didnt help.

 

[Howard Sterndrive]

Re: 1984 seaswirl will not idle after 30 min

compression test the engine hot.
if compression is good, check spark when hot and see if it's a nice bright blue spark.
You might also check the tank vent. Or run with the fuel cap loose and see if that helps.
Any exhaust leaks on the engine?

 

[jerryjerry05]

Re: 1984 seaswirl will not idle after 30 min

Check the coil.
After the motor heats up.
Touch the coil,it shouldn't be so hot you can't keep a finger on it.
Like Howard suggests the tank vent line,buggs just love getting in there and making nests.

 

[Will6508]

Re: 1984 seaswirl will not idle after 30 min

Check the coil.
After the motor heats up.
Touch the coil,it shouldn't be so hot you can't keep a finger on it.
Like Howard suggests the tank vent line,buggs just love getting in there and making nests.

I checked the tank vent and ran it with the fuel cap off. It still died after about 35 minutes of running strong. I also checked the coil and it was not hot at all and it seemed to be sparking fine at the distributer cap.

 

[Boomyal]

Re: 1984 seaswirl will not idle after 30 min

Many unknowns here like the condition of the plug wires and plugs. Have you checked the spark at the plugs themselves. Does it die all at once or does it sputter? Does goosing the throttle, while in the process of dying, have any effect? Have you looked down the carb throat to see if the accelerator pump is delivering fuel?

 

[Will6508]

Re: 1984 seaswirl will not idle after 30 min

Many unknowns here like the condition of the plug wires and plugs. Have you checked the spark at the plugs themselves. Does it die all at once or does it sputter? Does goosing the throttle, while in the process of dying, have any effect? Have you looked down the carb throat to see if the accelerator pump is delivering fuel?

Sparks good at the plugs. The accelerator pimp was revuilt with the carb. It dies immediately with no sputtering and goosing the throttle doesnt help.

 

[Howard Sterndrive]

Re: 1984 seaswirl will not idle after 30 min

is the choke bi-metal heat spring hooked up and working? (or heat pipe if 2 barrel)
did you do the compression test? That's first.

 

[Boomyal]

Re: 1984 seaswirl will not idle after 30 min

Sparks good at the plugs. The accelerator pimp was revuilt with the carb. It dies immediately with no sputtering and goosing the throttle doesnt help.

I didn't ask if the accelerator pump was rebuilt. I asked if you could see it squirting when you are having the issue. It only takes three things for an engine to run, ie, fuel, fire and air. Even engines with poor compression can run smooth. It just may not have any power.

 

[jbetzelb]

Re: 1984 seaswirl will not idle after 30 min

I dealt with this on my 89 4.3. I rebuilt the carb and still had the problem. I replaced the power band on the carb (a second time because one came with the carb kit) and the problem went away. I am not sure why the power band would cause the problem I had but an old school marine mechanic told me to try another power band and it worked.

 

[pattyson]

Re: 1984 seaswirl will not idle after 30 min

Ive had the same problem on my 84 seaswirl 3.8, and other boats. It was a simple fix. Pull the round cover on the floor that covers the full tank. Inspect the small fuel line (3/8th I think) that goes to your fuel / water seperator. It might be cracked and is sucking air thus no fuel. I have had about 4 instances of this happening. Or maybe your water seperator is plugged? I'll bet its the fuel line.
Good luck
Dave

 

[skier-24]

Re: 1984 seaswirl will not idle after 30 min

I dealt with this on my 89 4.3. I rebuilt the carb and still had the problem. I replaced the power band on the carb (a second time because one came with the carb kit) and the problem went away. I am not sure why the power band would cause the problem I had but an old school marine mechanic told me to try another power band and it worked.

What is the "power band"?

 

[MikDee]

Re: 1984 seaswirl will not idle after 30 min

What is the "power band"?

Is that the Power valve, & spring?