Again with the '78 70hp evi

[fireman57]

Finally have other stuff fixed but now back to the original problem. The dang thing literally runs out of gas. So far:
Pumping the bulb keeps it going. Fuel pump right? Nope same thing with a new fuel pump. Three different tanks with three different hoses and the same thing. You can get up on plane and after about 20 seconds it just loses power. Spark is all good at that point. Floats are set correctly.
tomorrow will put clear hose on again and see what is going on. Tanks are all vented. Before I was getting air in a line from a tank but that problem has been fixed. At one point it was like all the floats opened at once and there was a surge of fuel through the clear fuel filter but once that filter emptied it was a no go for the engine.
I guess what I am asking is how can it run out of gas with a good fuel pump and the floats opening correctly?

 

[fishfeatures]

Re: Again with the '78 70hp evi

have you done anything with the carbs? Had symptoms like this once and the core plugs weren't seated right when replaced.

 

[fireman57]

Re: Again with the '78 70hp evi

all of that is fine. Even use fingernail polish over them after I do them. Two reasons. one is I know that they are sealed and two that I did them!.
It seems like for some reason the middle carb might not be feeding the upper and lower for some reason.

 

[fishfeatures]

Re: Again with the '78 70hp evi

all of that is fine. Even use fingernail polish over them after I do them. Two reasons. one is I know that they are sealed and two that I did them!.
It seems like for some reason the middle carb might not be feeding the upper and lower for some reason.

Seems weak pump symptoms alright , any chances that the pump you swopped out needed a overhaul??

 

[Daviet]

Re: Again with the '78 70hp evi

Could you be sucking air from a fuel line connection before the pump?

 

[fireman57]

Re: Again with the '78 70hp evi

that is what I feel it is but it is a brand new fuel pump (120.00) and I'm afraid if I take it apart to check it then I can't return it. It did the same thing with the old pump that is why I thought a new one might solve it.

 

[fireman57]

Re: Again with the '78 70hp evi

Daviet I have even removed all the connections except the primer bulb and ran the line directly to the fuel pump and stuck the other end without the quick connect on it directly in the fuel tank. That way I could eliminate any connections. I'm really stuck here.

 

[Daviet]

Re: Again with the '78 70hp evi

Have you actually done a fuel pump pressure/flow test?

 

[fireman57]

Re: Again with the '78 70hp evi

I have taken the hose off and it shoots halfway across the yard. I am going to put the clear line on it tomorrow and make sure that it doesn't stop flowing. Anything else to try? I'm all ears.

 

[Will Bark]

Re: Again with the '78 70hp evi

My 15 rude was doing the same thing as you describe and what I did was to set the float drop to the max 1 1/2" which kept more fuel flowing; have had no trouble with it so far. Maybe something you would want to try.

 

[fireman57]

Re: Again with the '78 70hp evi

I thought about readjusting them but I'm afraid then they won't shut off. Right now they are level with teh carb turned upside down. It's like all three open at teh same time and then can't get enough fuel in time. It never picks back up unless you stop for about three or four minutes and the bowls refill. Then we can run about about 20 seconds before it does it again.

 

[1kruzer1]

Re: Again with the '78 70hp evi

Daviet I have even removed all the connections except the primer bulb and ran the line directly to the fuel pump and stuck the other end without the quick connect on it directly in the fuel tank. That way I could eliminate any connections. I'm really stuck here.

Have you tried a completely different fuel hose including the primer bulb? Wondering if you have a goofy check valve in the primer bulb. Also, when running at high speed the carb floats don't really open and close in surges. With slight up and down fluctuations the fuel flow into the carbs settles pretty quickly into a constant flow. The fact that pumping the primer bulb keeps her going tells me you are correct that this is not a carb issue, but a fuel flow issue. What is the condition of the impulse line going to the fuel pump?

 

[Will Bark]

Re: Again with the '78 70hp evi

Still sounds to me that your floats are shutting the fuel flow off too quickly but I may be wrong.

 

[fireman57]

Re: Again with the '78 70hp evi

kruzer: Have tried three different tanks with three different hoses. Getting ready to head out on the river and put some clear fuel line on it ans see what comes out of the fuel pump. The pulse line is new and open. Pulse is strong too so it shouldn't be a crankcase issue.

 

[fireman57]

Re: Again with the '78 70hp evi

Will, they all three wouldn't be shutting fuel off at the same time. I am going to try to raise them just a tad if the clear hose trick doesn't yield anything today.

 

[fireman57]

Re: Again with the '78 70hp evi

Alright, here is what happened. I would have posted this sooner but we were enjoying victory barley sodas. I have to admit that it wasn't me but a buddy of mine, Jason, who figured it out. We realized that it was not a fuel issue but a losing a cylinder issue. We knew if we let it cool down even for three or four minutes that it would run okay for 20 or thirty seconds. he asked me about the thermostat wire and I told him that I didn't think that this engine had the "slow" mode on it and he kind of agreed. We unhooked the brown wire and low and behold it ran like it should have. We even could feather it for the most part and take off and run without hitting the choke with the key. It still needs a lower pitch prop for even any resemblense to a hole shot but that can be taken care of. Hats off to my buddy Jason for figuring this out. I think that his training as an electrical engineer helped because I don't think that I would have thought of this myself. Especially when we knew we were dropping a cylinder. Automatically think that it is a coil or a powerpack.Thanks to Jeff for some parts at a ridiculosly low rate so we have spares if we would need them in the future. Mostly kudos to Jason. If anyone is having problems like we had you can at least undo the brown wire coming out of the thermostat and run it and see what happens. Thanks for all the help but I also have been around these things long enough to know what to test, but like many of you have said, everything acts like a fuel problem.

 

[boobie]

Re: Again with the '78 70hp evi

Sorry, but that mtr didn't have "slow". Something else is going on and may still act up.

 

[1kruzer1]

Re: Again with the '78 70hp evi

Sorry, but that mtr didn't have "slow". Something else is going on and may still act up.

Agreed. If somehow this fixed your problem I'm happy for you, but all that wire connects to is a switch that completes the circuit to ground on an overheat which sounds the horn in the control box. Also, you previously stated that pumping the primer bulb would keep the motor going at speed.
Doesn't make sense.

 

[willamettejeff]

Re: Again with the '78 70hp evi

Agreed. If somehow this fixed your problem I'm happy for you, but all that wire connects to is a switch that completes the circuit to ground on an overheat which sounds the horn in the control box. Also, you previously stated that pumping the primer bulb would keep the motor going at speed.
Doesn't make sense.

Agree with both of the above. The only way the thermostat wire could be shutting down the motor is if it was crossed to the black/yellow wire to the power pack somewhere. Normally there is no connection between these 2 wires. To check, reconnect the thermostat wire and disconnect the black/yellow wire from the power pack. This wire is taken to ground by the ignition switch to shut off the motor. After it is disconnected you will have to activate the choke or ground the terminal on the power-pack where it was connected to kill the motor. Caution, there is 300 volts on this terminal when engine is cranking or running. Smarts a bit. Suspect issue is in the control box. Then again, why would the overheat thermostat be activating in the first place? Hmm!

-- Jeff

 

[Will Bark]

Re: Again with the '78 70hp evi

It's going to be interesting to find out where that wire is connected to cause that; I thought that 1988 was the first year tha SLOW was introduced. That wire shouldn't be going to ground unless the sensor was flaky. Fireman, let us know what you find.