1992 Force 40 HP won’t run in gear

[joemarshall]

I have a 1992 Force 40hp that i bought used this summer. After i bought it, threw it in the water, drove it for 5 mins and the engine died, couldn’t get it running. Note, i live in the upper midwest and the boat has been used in mainly in florida. i paddled back to the landing and dropped it off at the marina to check it out. they cleaned and rebuilt the carbs, and replaced the fuel line.
Last week i picked it up, put it in the water and noticed it is hard to start, but after it gets going and i put it in gear, the engine dies. in order for it to run, i have to turn the motor on, then quickly shove the throttle to full speed, then engine revs up and gets going. So the engine idles weakly, and stalls when i just set it in gear. I don’t want to take it to the marina again just yet without getting additional advice.

Here is a list of things i have tried:
New spark plugs
New thermostat
New fuel line
Cleaned carburetors

Here is a list of possible culprits in my opinion and based on my research:
Replace/clean fuel pump
New fuel filter
New head gasket
New reed valve

Could any of those issues be the main cause, or is there something else that i am not looking at? i appreciate the help!

 

[racerone]

Mixing gas and oil at 50:1 on this motor ?----Did you test overheat horn ( if equipped ) ??----And have you checked water pump impeller ?-----Do a compression test and post your numbers here.----Does spark jump a gap of 3/8" on both leads , yes or no ?

 

[ThomW]

You replaced the fuel lines...but what about the tank and gas in it? Was it old gas? Is the tank clean inside? Like Racerone said...start with the basics. Check compression, spark, and make sure its getting good clean gas.

 

[joemarshall]

Mixing gas and oil at 50:1 on this motor ?----Did you test overheat horn ( if equipped ) ??----And have you checked water pump impeller ?-----Do a compression test and post your numbers here.----Does spark jump a gap of 3/8" on both leads , yes or no ?

yes, 50:1 (currently has premium gas). i have not checked the water impeller system. now that i think about, if this boat was in salt water all the time, i bet that could’ve chewed it up. at the marina they said the compression test was fine. i am not sure about the spark gap, where are the leads located?

 

[Jiggz]

On two cylinder engines, it's really hard to tell if there is a misfire or if one cylinder is not firing at all. Do a quick cylinder drop test first to make sure it is actually firing on all cylinders. Always make sure you have cooling water with muffs connected. If it's firing on all cylinders when you pull one of the plug wires (round black one) it should continue to run albeit rough. If it dies, then it is only firing on one cylinder.

A bad reed cannot be detected with compression test. Instead, the best indicator is fuel spitting out of the carb. Or better yet using a bore scope, with the throttle in full open you can insert a bore scope through the carb and check the reeds.

If it idles fine, make sure it is set properly. Normally, that would be 800~1000 RPM in neutral and around 700~750 rpm in gear minimum/idle.

As for fuel, invest in a $6 in-line clear fuel filter and connect it between the fuel pump outlet and the carb inlet. In this way, you can actually see if the fuel pump is actually delivering fuel. Wally store has them in two different size depending on the fuel hose size.