Hi. Thanks for reading.
First off just want to say that searched around and reviewed other posting before starting a new post. I've reviewed Don S's post on HOW TO: Testing Your Boats Fuel System. Great info Don, thanks. And some other posts and the great information that was provided. Thought I sure had a problem with the search engine!
Here is my situation. I have a 97 Larson SEI 186, 43L GL, Volvo SX. It has an eclectic fuel pump with a Holley 2Bbl Model 2300 carb.
The last couple weeks it has started acting up. No problems initially getting it started or problems when running at any speed. However after shutting it off and sitting for a while it would not start. This happened on about 3 separate occasions on separate days. After a lot of cranking and priming the carburetor the engine would finally start.
The last couple times it happened I pulled the gas line off the fuel pump and noticed there was no gas visible in the line, I sucked on the line and was able to pull gas from the tank. (I know, not a good idea, but what do you do when you a stuck in the middle of the lake?) I reconnected the line it popped right off. So I figured I had problem in the supply side. Clogged screen, anti siphon valve, sucking air, etc. Later that weekend the same thing happened and I again sucked on the fuel line and again was able to pull gas, but this time when I reconnected, it would not start. After being towed to the landing we pulled flame arrester off and could see the carb was dry as a bone. Poured some gas in and would start but die as soon as the gas was burned up. Did this a couple times, same thing. Then I pumped the primer a couple time and it popped off and has run ever since.
I've since run the engine with a vacuum gauge in between the tank and the pump and get a vacuum reading of 3.2 in. of mercury (Hg).
I put a jumper on the fuel pump with the line disconnected from the carb and get a pressure reading of 3.5 lbs. Also verified that fuel pump is pumping gas when the engine is cranking over. Figured this was important because the problem is with starting. Once it running its fine, which to me rules out the oil pressure switch. Right?
Also put a vacuum on the supply line before the pump and it took about 5 in. of mercury (Hg) before it would pull gas from the tank. Not sure how accurate this measurement was because I had the pump about level with the top of the engine on the back of the back seat, which is about foot higher than the fuel pump, not sure if that matters?
I have pulled the floor to get to the gas tank. What a job!!!! Ive never spent so much time trying to hunt down 14 screws in my life!! No real pattern or anything. Seamed like the just put them were they wanted. Im definitely going to take measurements before I put them back in, just in case it needs to come out again.
Since Ive gone to this much effort, I was thinking of replacing the gas line and the anti siphon valve regardless, as long as Im there anyway. Figure and ounce of prevention I will also pull the pickup tube and make sure the screen in clean.
So finally Im not sure Ive proven anything through all this. Do I still need to run a vacuum gauge between the carb and the fuel pump and run under a load to rule out a fuel supply problem or can I assume the problem is in the carburetor? I did not do this as I dont have the fittings yet, but will get them if needed. The fuel filter/water separator is new this year and I also drained and reinstalled it. The screen on the carb was clean as a whistle.
Sorry for the long story. And for those that made it through, thanks in advance for your help!
John.
First off just want to say that searched around and reviewed other posting before starting a new post. I've reviewed Don S's post on HOW TO: Testing Your Boats Fuel System. Great info Don, thanks. And some other posts and the great information that was provided. Thought I sure had a problem with the search engine!
Here is my situation. I have a 97 Larson SEI 186, 43L GL, Volvo SX. It has an eclectic fuel pump with a Holley 2Bbl Model 2300 carb.
The last couple weeks it has started acting up. No problems initially getting it started or problems when running at any speed. However after shutting it off and sitting for a while it would not start. This happened on about 3 separate occasions on separate days. After a lot of cranking and priming the carburetor the engine would finally start.
The last couple times it happened I pulled the gas line off the fuel pump and noticed there was no gas visible in the line, I sucked on the line and was able to pull gas from the tank. (I know, not a good idea, but what do you do when you a stuck in the middle of the lake?) I reconnected the line it popped right off. So I figured I had problem in the supply side. Clogged screen, anti siphon valve, sucking air, etc. Later that weekend the same thing happened and I again sucked on the fuel line and again was able to pull gas, but this time when I reconnected, it would not start. After being towed to the landing we pulled flame arrester off and could see the carb was dry as a bone. Poured some gas in and would start but die as soon as the gas was burned up. Did this a couple times, same thing. Then I pumped the primer a couple time and it popped off and has run ever since.
I've since run the engine with a vacuum gauge in between the tank and the pump and get a vacuum reading of 3.2 in. of mercury (Hg).
I put a jumper on the fuel pump with the line disconnected from the carb and get a pressure reading of 3.5 lbs. Also verified that fuel pump is pumping gas when the engine is cranking over. Figured this was important because the problem is with starting. Once it running its fine, which to me rules out the oil pressure switch. Right?
Also put a vacuum on the supply line before the pump and it took about 5 in. of mercury (Hg) before it would pull gas from the tank. Not sure how accurate this measurement was because I had the pump about level with the top of the engine on the back of the back seat, which is about foot higher than the fuel pump, not sure if that matters?
I have pulled the floor to get to the gas tank. What a job!!!! Ive never spent so much time trying to hunt down 14 screws in my life!! No real pattern or anything. Seamed like the just put them were they wanted. Im definitely going to take measurements before I put them back in, just in case it needs to come out again.
Since Ive gone to this much effort, I was thinking of replacing the gas line and the anti siphon valve regardless, as long as Im there anyway. Figure and ounce of prevention I will also pull the pickup tube and make sure the screen in clean.
So finally Im not sure Ive proven anything through all this. Do I still need to run a vacuum gauge between the carb and the fuel pump and run under a load to rule out a fuel supply problem or can I assume the problem is in the carburetor? I did not do this as I dont have the fittings yet, but will get them if needed. The fuel filter/water separator is new this year and I also drained and reinstalled it. The screen on the carb was clean as a whistle.
Sorry for the long story. And for those that made it through, thanks in advance for your help!
John.
