Bogging down

[t_south91]

Hello again guys...sorry I know I have been posting a lot but I have a project on my hands.

As you've probably read I have 3.8l with a stringer 800. I've replaced the water pump shaft, upper drive shaft and impeller on the outdrive. Now I am having trouble getting the engine to run well.

I have put new spark plugs and spark plug wiring in it but it still isnt good. Whenever I put the throttle all the way down it acts like it wants to die. Or if I am cruising along at 3/4 throttle and put it down further it begins to slow down. I do know that I need a new prop to help my hole shot (have a 21p right now) but the boat shouldn't want to die when I put the throttle all the way down. Thinking maybe it's the carb, fuel pump or lines? Any ideas??

This thing should be able to run about 45-50 and I am barely touching 35 in perfect conditions and trimmed.

Thanks a lot guys. Y'all have helped me so much thus far!

 

[Bondo]

Hello again guys...sorry I know I have been posting a lot but I have a project on my hands.

As you've probably read I have 3.8l with a stringer 800. I've replaced the water pump shaft, upper drive shaft and impeller on the outdrive. Now I am having trouble getting the engine to run well.

I have put new spark plugs and spark plug wiring in it but it still isnt good. Whenever I put the throttle all the way down it acts like it wants to die. Or if I am cruising along at 3/4 throttle and put it down further it begins to slow down. I do know that I need a new prop to help my hole shot (have a 21p right now) but the boat shouldn't want to die when I put the throttle all the way down. Thinking maybe it's the carb, fuel pump or lines? Any ideas??

This thing should be able to run about 45-50 and I am barely touching 35 in perfect conditions and trimmed.

Thanks a lot guys. Y'all have helped me so much thus far!

Ayuh,.... Sounds like a fuel restriction issue,... The carb maybe,....

Too big a prop would compound the issue,....

What Color are the spark plugs when ya run it up like that,..??

 

[southkogs]

How long has it not been going up to the 45 or 50 MPH range? How big is your boat?

 

[user-name]

How wet is your boat?
In other words how much water is in the foam?
How heavy is it now? how heavy was it new?

 

[Howard Sterndrive]

also clean flame arrester, check timing and fuel pressure to inlet of carb (4-7 psi), check carb linkage - make sure opening full and choke not closing on you, make sure no exhaust leaks feeding exhaust to the engine (go for a run with doghouse off)
I would also have a look at the advance weights and springs in the distributor (under the points plate) - they'll likely be all gummed up with 30 year old oil sludge - not allowing your timing to advance at higher rpms.

 

[t_south91]

Southkogs - I just got this boat. So I am not sure when the last time it the 45-50 range. It hasn't been run in over 2 years... I just know with the powertrain and being an 18ft boat this is the range it should be in.

Not sure how heavy the boat is now...I know in '85 it was supposed to be 1900lbs. But I lift it into the trailer hitch all the time so it can't be to heavy. And no clue about the foam. Bought this boat as a project and just wanna have some fun this summer and do some skiing.

Howard Sterndrive - I will def check all those things you pointed out.

Just an update so far... I took it out today after replacing the spark plugs, spark plug wiring, fuel filter and new fuel line because the old one was collapsed. Result was much better. But still started slowing down when the throttle was placed in the WOT position. Took apart the carbs tonight and have them soaking and will replace the gaskets, etc. tomorrow when I pick up the kit. Also ordered a 17p prop which should also help my hole shot issue.

Thanks for all the help thus far guys! Y'all are awesome.

 

[southkogs]

Southkogs - I just got this boat. So I am not sure when the last time it the 45-50 range. It hasn't been run in over 2 years... I just know with the powertrain and being an 18ft boat this is the range it should be in.

45-50 MPH in a 35 year old 18' may be a bit sporty. I can't tell you for sure because there are other factors, but my boat is a '72 18' with a straight 6 (165HP). Dry, she's about 1400# then add engine. She's propped right now with a 16p, and I'm in the low 30's at the top end. According to what I can figure out about the boat, I should be gettin' a bit more outta' it - but probably not too much. I'm thinking between 35 or 40 on the top end would be right where she should be.

My folks have a newer 19' with a 3.0 that will tag the low 40's with just 2 people in it, so I'm not saying yours can't get up there ... but don't "over expect" outta' it either. Just my 2¢.