Good morning, and sorry for the delay. We all do this on the side. When you replied back last night I was logged off for the evening.
The engine needs 3 things to both run and make full power. What it needs is compression, timed spark ignition (spark happening at the right time) and the proper ratio of fuel to air.
When I get engines in the shop that do not make full power, this is what I do to troubleshoot them, I also do it in this specific order in order to both be thorough and keep from making mistakes.
What I start with is engine compression and spark tests.
1. Compression test. Results need be 90 psi or better, all cylinders should be within 10-15% of eachother. If any cylinder is under 90 psi it is either worn out or has cylinder damage.
2. Spark test. The easiest thing to do here is to hook up a timing light to each plug wire one at a time and see if the light flashes or not. Flash means spark, no flash means no spark. No spark can be something as simple as a bad spark plug, that was dropped on the floor before you got it, or a bad plug wire.
3. If compression and spark are good, make sure the fuel filters are all changed.
4. Next is to get a small outboard tank (like a 3 gallon) and fill it up with known new fresh gas and try it. If the engine runs better on the portable tank there is an issue with the boats tank, this can be a blockage or air leak in the fuel pickup and related hardware on the boats tank and related lines. As well as the gas in the boats tank simply being bad.
5. If no change, next is to hook up a fuel pressure gauge between the pump and carb. Fuel pressure needs to be in the 3 to 7 psi ballpark at max speed. If it's not, the fuel pump is weak and needs to be changed out.
6. Lastly, if you got this far and the engine STILL is not running correctly, everything else has been ruled out at this point, and the problem is inside of the carb. The carbs will need to properly cleaned and rebuilt.
If the troubleshooting is done in that order, and no steps are skipped, the root cause will ultimately be found. Also keep in mind there is always a chance there is more than 1 thing wrong with the engine. So if for example if you pull apart the fuel pump and change the filter inside of it, and it looks nasty but the boat still does not run correctly, try not to get discouraged. The older the boat is the odds of it having more than one problem goes up. I couldn't tell you how many engines I have worked on that have come in and the boat has bad gas in it, all the filters are trashed, the ignition system needs a tune up, and the carb is clogged as well. It definitely does happen.
I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.
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