1975 115hp dies at WOT after running for a few minutes

[warrior1]

this is a 1975 115hp, rebuilt carbs, fuel pump and known good fuel line. recently link and synched. i also use 2 6 gallon portable tanks.

1. after launching, i head out and hit the throttle. after about a couple of minutes running at WOT, the engine bogs and dies, suddenly. the first time this happened, i thought i had fouled my prop on a net or rope we slowed down so quickly. nothing on prop though.
after then sitting for a few minutes, i crank the engine over and it will only try to fire when i apply the choke and raise the idle lever. after a couple of times of trying to start it, it will finally fire up and run. then after a few minutes of WOT, the same thing happens again.

2. the engine also hiccups at idle and then dies. restart it, idles for a few minutes, then hiccups and dies again.

all help is appreciated.

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

The hickup leads me to believe your outboard is starved for fuel or running with a lean condition. When you rebuilt the carbs, did you set the floats parallel with the carb body when held upside down? Did you install new kits with a new needle, seat, and float? Mine did the same thing as your describing here, a few months back, only without the hickup. I rebuilt the fuel pump and carbs again and all is well now. I suspect the fuel pump was the culprit. Start with the basics though. Check the compression and make sure everything is still intact, first and foremost. Post the results of the test to verify. If everything checks out ok with the compression, you might consider taking a closer look at the carbs to make certain they are spotless. See the sticky note at the top of this board for directions on cleaning the carbs and rebuilding the fuel pump as well. You may find them very interesting. Good Luck!!!............. ALAN

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

engine compression is within specs on all 4 cylinders.
new needles and floats in carbs. maybe i did not set the floats correctly.
i will check that next.
i will add this, when the engine dies, the fuel bulb has not pulled a vacuum. also the tanks are vented, at the cap.
thanks for the suggestion.

 

[wavrider]

Re: 1975 115hp dies at WOT after running for a few minutes

Sounds lke combination of carbs not ste correctly or dirty jets and fuel pump issue.

I have a 1978 115 jonny, same thing rebuilt carbs and it still fall on its face at WOT, changed fuel pump and fixed the problem.

1973 85hp, fell on its face, rebuilt carbs and still same problem, rebuilt those carbs twice, then bought new fuel pump, turned out who ever had it before me had installed a small hp fuel pump on it, with correct pump it runs great.

rebuild carbs, pay close attention to jets, run a wire through them to make sure they are clean, and then try it out, if still have same problem then look at fuel line or fuel pump.

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

thanks for the help. i will check out the fuel pump again. it is the standard pump, not the high performance pump.

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

thanks for the help. i will check out the fuel pump again. it is the standard pump, not the high performance pump.

These may be of interest to you ...............

http://forums.iboats.com/showthread.php?t=244013

http://forums.iboats.com/showthread.php?t=240864

 

[jtexas]

Re: 1975 115hp dies at WOT after running for a few minutes

When it dies, is the primer bulb still firm? If so then the carb bowls are full and the pump is good.

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

If not, you should consider checking the antisiphon valve prior to spending any money on it. Could be sticking. Some folks recommend removing the check valve completely. This is a common problem. Also look into the fuel line connection to the outboard if it still has it. Sometimes the seals leak and allows air to infiltrate the system. Personally, I removed it and ran a straight fuel line to the pump. Good luck........... ALAN

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

If not, you should consider checking the antisiphon valve prior to spending any money on it. Could be sticking. Some folks recommend removing the check valve completely.

what is the antisiphon valve and where is it?
also which check valve are you talking about?
are these on the gas tanks?

btw. yesterday we took the boat out and it repeated the cycle. however, we quickly looked back and the fuel bulb was flat. after a few seconds, it started to return to its normal state. so, we double checked the vents on the gas tanks, and they were open. pumped up the bulb and away we went.
now, when running it at 1/2 to 3/4 throttle, there was no problem.

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

what is the antisiphon valve and where is it?
also which check valve are you talking about?
are these on the gas tanks?

LOL..... It looks like your about to find out. The bulb being sucked flat is a good indication that you have a fuel restriction AND that your fuel pump is likely good to go. Now your making some progress!!!! Are you running the outboard from a remote or onboard (built-in) fuel cell? That check valve is located within the pickup tube inside the fuel cell. Basically, it allows fuel to flow in ONLY one direction, to the fuel pump. Sometimes these valves get "sticky" and refuse to open when fuel is being pumped from the fuel tank via the fuel pump. If it sticks, closing off the fuel supply, the pump sucks the bulb flat. Sound familiar yet? Most folks, that I know, often times remove this ball bearing shaped valve so that they are straight lining fuel to the pump. They can be frustrating little devils to get out sometimes. But they WILL come out. Also, there is a screen at the end of the pick-up tube that could possibly be clogged with a foreign object. Have you ever seen those reynolds wrap looking covers over the opening of a quart of oil? Wink........wink!!! I wonder how many fuel systems have fallen victim to them, don't you? Check these out and see what you can find. Personally, I'd elliminate the fuel line quick connect to the outboard and run a straight fuel line to the pump. It's just a matter of time before it bites you as well. Just my $.02. Best of luck to you.............. ALAN


EDIT: Sorry, I just went back and re-read your initial post and learned that you are using (2) 6 gallon tanks. Are you using them simultaniously? Or one at a time?

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

yes my astute friend, i am using portable 6 gal tempo tanks.
we run one tank at a time. we have tried both tanks and it still dies regardless of which tank is used.

thanks in advance and as always, all help and suggestions are appreciated.

 

[iwombat]

Re: 1975 115hp dies at WOT after running for a few minutes

What size hoses are you running? You might need a size bigger.

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

What size hoses are you running? You might need a size bigger.

This seems to be the only other option. A real head scratcher huh? Does it suck the bulb flat on BOTH tanks? Also, do you use any type of quick connect for the tanks whereas you disconnect from one and connect the same line to the other? Or do they have seperate hoses altogether? You DO have the arrow on the bulb(s) flow direction pointing in the right direction, right? Did both tanks sit over the winter months with fuel in them? It could possibly have jelled in both tanks. No kinks or otherwise pinched fuel line(s) below the bulb and between the fuel cell and bulb? Look for ANYTHING that might obstruct the flow of fuel here such as a door closed on the fuel line etc etc....

 

[72SideWinderSS]

Re: 1975 115hp dies at WOT after running for a few minutes

check for red debris in the fitting. Unscrew the quick connect from the tank and look inside the fitting, might find debris in there.

 

[Ike-110722]

Re: 1975 115hp dies at WOT after running for a few minutes

Just a comment. Won't solve your problem, But it sounds like there are some people here who can help. However,,,, I would never recommended removing an anti-siphon valve except under certain specific conditions. First what is an anti-siphon valve? As was said it is a one way valve that only allows gas to flow to the engine. The reason for it is because if the fuel tanks are higher than the fuel inlet on the engine and something goes wrong on the engine, it is possible for the fuel to be siphoned out of the tank straight into the engine flooding the carbs and manifold and resulting in a fire. The little spring in that valve is calibrated to allow the valve to open when the fuel pump starts sucking on the hose. When the fuel pump shuts off, or if there is a leak in the line or pump the valve closes shutting off the fuel flow.

The valve is usually located at the fuel outlet from the tank. On permanently installed tanks it is screwed into the fuel outlet and is usually square. The hose connects to the outlet of the valve.

If the engine is higher than the tank then the valve is not required. In other words if the fuel line runs up hill you don't need it. It can be removed and there should be no problem. But if the tanks are higher than the engine do not remove the valve.

Yes the nasty little buggers clog up and cause fuel starvation. The best solution is just replace the thing.

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

What size hoses are you running? You might need a size bigger. cant remember off the top of my head, maybe only 5/16. however, this line came off of my 78 140hp rude, that ran just fine. i will upgrade to 3/8 if necessary

Does it suck the bulb flat on BOTH tanks? yes

do you use any type of quick connect for the tanks whereas you disconnect from one and connect the same line to the other?yes

You DO have the arrow on the bulb(s) flow direction pointing in the right direction yes, been there-done that:redface:

Did both tanks sit over the winter months with fuel in them? no, no fuel left in them. fueled with fresh gas

No kinks or otherwise pinched fuel line(s) below the bulb and between the fuel cell and bulb? none

check for red debris in the fitting. Unscrew the quick connect from the tank and look inside the fitting, might find debris in there. will do.

Look for ANYTHING that might obstruct the flow of fuel here such as a door closed on the fuel line etc etc.... will do

thanks for all the suggestions, i will check this out tomorrow or the next day.

 

[emdsapmgr]

Re: 1975 115hp dies at WOT after running for a few minutes

Possible that one of the valves in the fuel line squeeze bulb is stuck/defective. Try another fuel line...

 

[Theoutdoorsman]

Re: 1975 115hp dies at WOT after running for a few minutes

do you use any type of quick connect for the tanks whereas you disconnect from one and connect the same line to the other?...............yes

I'd be looking here for the problem. Inspect this coupling closely.

 

[wavrider]

Re: 1975 115hp dies at WOT after running for a few minutes

changed tanks used same fuel line and primer bulb
there is the culprit, replace that primer bulb and line if you can, doubt if 2 tanks are bad but they could be. you about to get it fixed. the fuel pump is working if it flattens out the primer bulb.

fuel line off of your 140?? Man what I would give to get my hands on one of those old air pumps.

 

[warrior1]

Re: 1975 115hp dies at WOT after running for a few minutes

well, i appreciate all the help and suggestions.

took the boat out today with a new bulb and could not duplicate the problem, soooo.. im going to say/guess that this fixed it. (thats how they do it at the dealership!!)

once again, thanks for the help.
sometimes its the smallest things that get you.