'74 V-4 115HP Fuel overflow problem

I have this old '74 V-4 115 HP engine I am trying to get running after sitting for 10 years. It starts and runs at a high idle when being backed into a lake on the trailer. I cannot slow the idle without killing the engine.

I am leaving a large gas slick on the water. From the best that I can tell, I am getting a pulsating slug of fuel pumped out of a port on the bottom of the air cleaner bracket. I took the engine off the boat, pulled off the carbs to clean them as I thought maybe the carb floats were sticking causing fuel to overflow. After taking the carbs apart, they did not look that bad on the inside.

I now can see that the hose that connects to this port goes to the engine block. I have two pictures showing the hose and where it attaches to the air cleaner. BTW... I do NOT have the air cleaner for this engine... never had it although I used this engine quite a bit over 10 years ago with no problems.

Can anyone tell me why or how this hose is pushing fuel out and how I can fix this excess fuel from overflowing through that port?

The first pic shows the port on the air cleaner bracket that is spitting fuel, and the second pic shows the hose in the middle that fits onto this port coming from the block (bottom carb removed).

Thx for the help...

There were no air filters installed in those motors !!-----------Check for a ruptured fuel pump diaphragm.That might be a cause of fuel coming out of that hose.--------That small hose is a safety item to get rid of spilled fuel in the silencer assembly.

Well, I took off both carbs and cleaned them inside and out with carb cleaner. They were both pretty clean on the inside, with no indication of deposits. I put the boat in the water today and started it up. It ran, but would act like it was choking out after warming up for about a minute. I took off the cover to try and see what was happening. Sure enough, fuel was still spurting out of the hose that I mentioned, and it looked like a lot of fuel was running out of the lower carb. I tried starting the engine with just the top two (V-4 engine) plug wires attached, and it started. I thought maybe I had two bad lower cylinders and the fuel was not being burnt in those cylinders. I then plugged in one of the lower spark plugs and it ran smoother, then the other plug wire and it ran faster and smoother, but still wanted to choke out. I brought the boat home from the lake and checked the fuel diaphragm as was suggested above. I think that is the thin piece of rubber in the middle of the fuel pump... right? Well I did not see any splits or tears, but it does seem to be badly misshapen and distorted. I am going to try to find a replacement. Wish me luck. Does this fuel dumping out if the carb sound like anything other than a bad fuel pump diaphragm? Thx for the help.

Update on what I did to correct this problem... I did order a replacement fuel pump. It is not OEM, but a copy from Sierra International via Amazon. I installed it with no problem. The engine started right up after pumping up the bulb, but I knew something was still wrong because as I pumped up the bulb fuel was overflowing from the lower carb. After fooling with this problem again after my original post, I found that fuel was not spurting out of the hose that I mentioned, but was in fact just running out of the lower carb. And I mean FLOWING out rapidly. I took the carb off. This time I just took off the lower carb. I just knew there was something wrong with the needle valve on the float. I took the entire float assembly apart and checked the needle valve. There was absolutely no dirt or corrosion to keep it from sticking. I then noticed some "dirt" in a port on the carb. I poked it with a small screwdriver, and sure enough what looked like mud crumbled from the port. I kept prodding and poking and more and more dirt came out of the hole. I finally figured out that some insect must have flown into this port and built a mud nest in the carb. The port was a vent from the top of the fuel bowl at the bottom of the carb to atmosphere. It was about a 1/4 inch in diameter, and took a right angle bend to the front of the carb. I blew it out with air and used carb cleaner to clean out the entire port of a considerable amount of mud. After reassembling the carb and reinstalling, I pumped up the bulb and started the engine and BEHOLD... NO GAS overflow, and the engine ran smooth. In hindsight, I figure that this plugged vent port would let out any air in the fuel bowl and allow the float in the bowl to "float" which would then close off the flow of fuel into the carb. By not letting air escape through this port, the bowl would never get fuel full and allow the float to "float". Which brings me back to an original post of this engine has no air cleaner on it... racerone has pointed out there is no air cleaner on this engine... which I don't doubt, but there must be something that covers the entrance to this large port. As I mentioned in a previous post this engine is old and has sat for 10 years prior to this spring. I am going out this weekend and put some hours on this engine. I have also installed a fuel/water separator by "Seachoice" that I picked up on Amazon. I am going to run at least one tank of fuel at 40:1, then maybe back off a bit and get closer to 50:1. When I did run this boat years ago, I always used 50:1 + a bit with good results. I hope I can get away with NOT changing the water impeller, at least for a time this year. I suppose though that will be my next challenge with this engine.

If you are going to gamble with an impeller that may be 15 years old then at least test the overheat horn in the control box !

good idea... can you give me an idea of how I can test it?

Ground it on the engine block where the wire meets at a junction.

thx... did that and the horn works...now to find and order an impeller...