help with 1150 tower

Hi, first post here and new to outboards.
I have a 78' 115 hp merc that won't run more than 15-20 seconds.
So far I've replaced the fuel pump diaphram, fuel lines, fuel filter, cleaned all 3 carbs.
Replaced spark plug wires and cap. Getting over 120lbs compression in all cylinders, lots of spark.
I have a manual on the way. Just wondering if there was anything I could check in the meantime?
Pulling my hair out on this thing.

Thanks,
Tim

Re: help with 1150 tower

Will it continue to run if you keep squeezing the primer bulb? Does the bulb go flat?

Re: help with 1150 tower

It does not continue to run after I prime the ball and the ball stays hard.

Re: help with 1150 tower

check filter in top part of fuel pump

Re: help with 1150 tower

So far I've replaced the fuel pump diaphram, fuel lines, fuel filter, cleaned all 3 carbs.

Click to expand...

If the above good suggestions don't solve your problem, a simple troubleshooting test is to spay oil/fuel mix into the carbs during engine bog to see if the motor responds. If it does not respond, then you likely have an ignition related problem. If it does respond, you can can consider troubleshooting the problem with a vacuum gauge. With this gauge, you can test for a fuel line restriction between the fuel pump and fuel tank, a weak fuel pump, or an air leak in the fuel line. Any of these three situations can cause the sympoms you describe. If all three of these things check out OK, you won't need to spend any unneccessry time and money fixing/replacing these parts that are not the cause, and look elsewhere. If all three of these things check out OK, my guess would be that the carbs are not as clean as they need to be or the floats are not working correctly. Just my thoughts.

The below linked thread has a guide on how to use a vacuum gauge. The symptoms described in the thread may be different than yours, but the troubleshooting tests still apply.

http://forums.iboats.com/showthread.php?t=261581