Fuel Pump?

[XJMikey]

Question regarding my 81 7.5hp Chrysler Sea King outboard. I replaced all of the fuel lines on the tank and motor. I put a clear fuel line from the fuel pump to the carb so that I could see the fuel flow. I started the motor today and noticed that there was air in the fuel line from the pump to the carb. It was not there when I initially squeezed the bulb to prime the fuel lines. As the motor ran, more and more air began to fill the line and it has a very small flow of fuel. I had to keep sqeeezing the bulb to maintain fuel pressure in the line and to keep the motor running. Is the fuel pump dying? Like I said earlier, I replaced the fuel lines, so I can't think of how there would be leak allowing air in unless the quick connections from the tank to motor are bad. Any help is appreciated.

 

[JB]

Re: Fuel Pump?

You might ask where the air is coming from, Mikey.

It isn't coming from the tank, so it must be getting in a fuel line or connector leak or a leaky fuel pump diaphram.

 

[eurolarva]

Re: Fuel Pump?

rubber o ring at the quick disconnect is a good place to look.

 

[jerryjerry05]

Re: Fuel Pump?

The quick disconects go bad after time and SUCK air.If you can get away with it run it direct from the tank.Jerry

 

[XJMikey]

Re: Fuel Pump?

Thanks. I think I will start with running it direct from the tank and eliminating the quick disconnects. If that solves the problem, then I know what the issue is. If not, possibly a leaky diaphram at the pump? Thanks guys.

 

[XJMikey]

Re: Fuel Pump?

Well......today I started the motor up and waited for the air to get in the lines. I pushed hard on the quick disconnect fittings as to put more sealing pressure on them. The air in the fuel line went away. Cool!!! But.... when I let the motor idle down low, the air came back big time. Would the fuel pump/diaphram work fine at higher RPM's and not so good at lower RPM's? Seems like the pump may be in need attention. (And obviously the fittings need to be replaced.) What do you guys think?

 

[eurolarva]

Re: Fuel Pump?

Finding a kit for that motor is going to be tough The repair kit is
F10083 and has been discontinued. You could try Franz at chrysler crew and see if they have a kit for that motor. Looks like a small two stroke motor that has the carb and the fuel pump as one unit. Here is a diagram. Then again after re looking a gasket kit is available for around 5 bucks part number F10069 from mercury. That might have the diaphram and gaskets you need.

 

[XJMikey]

Re: Fuel Pump?

I ordered new parts for the fuel pump and new fuel line connections. Once I get it put together, I will cross my fingers and see if it did the trick. I will post back here with the results. Thanks again for the help guys!!

 

[john from md]

Re: Fuel Pump?

I suggest that while you have the fuel pump apart that you check the check valves for intermittant sticking. Don't just pust them one time, do it several times to see if they stick at all. Make sure you check all three. These only cost $5 each but can cause the engine to die intermittantly at different speeds.

Regards,

John

 

[john from md]

Re: Fuel Pump?

Disregard my post. I thought I was replying to a guy with a 125 hp engine.

John

 

[XJMikey]

Re: Fuel Pump?

I have not received my parts yet, but have another question regarding my issues. When I prime the bulb from the fuel tank, it puts fuel all the way past the fuel pump and into the carb. Is this right? Is it supposed to go past the pump?

 

[john from md]

Re: Fuel Pump?

Yes that is correct. When you pump the ball, you are filling the carb bowls and lines. As long as the check valves are good, the ball should stay hard. One way to check for bad check valves is to disconnet the line going from the pump to the carbs. Pump the ball and you should get a good flow of fuel and should feel no resistance when pumping the ball. If you feel like you are squeezing past an obstruction, then it is a good chance that your check valves are sticking.

Regards,

John

 

[XJMikey]

Re: Fuel Pump?

Update:

Replaced all of the fitting on the fuel line and still had the same issue with air in the line. I then replaced the fuel pump diaphram and gaskets. That seemed to have done the trick as there was very little air, if any, in the fuel line from the pump to carb. The reed check valves also looked to be in good shape.

I have found it hard to find parts specific to my 7.5HP as I have been told several times that there are no more parts available for those motors. I took out my factory service manual and noticed that it is not only for the 7.5, but also for the 6HP. I ordered the fuel pump parts for a 6HP, just to see, and it was a perfect fit. Maybe those of you with the 7.5 Chrysler Sea King's can look at 6HP replacement parts for your needs.

 

[eurolarva]

Re: Fuel Pump?

Seems the hardest to find parts are for Chryslers that are below 20 HP. When you do find them they are expensive. Case in point is an impeller for your motor is probably around 30 bucks and you can buy one for a 55 HP for 17 dollars. Fuel pump kit for a 45 is around 9 bucks.

 

[XJMikey]

Re: Fuel Pump?

That is correct, but unfortunately my boat is so small that if I had anything bigger than a 15 horse on my 12' aluminum Valco, I would sink. So, I am happy with the 7.5 for now. It did pretty darn good on the small river and sloughs here in the Sacramento Delta so far. Thanks for all the help everyone.