Fuel problem. I think.

[rlb9844]

Last couple of times I've been out I have had the same problem. I have an '79 Evinrude 150 that I always start before leaving home. On the muffs it starts and runs fine. When I get to the lake it runs great for myabe 15 min. Then it acts like its giving out of gas (running at 3/4 throttle the motor just dies back but doesn't die completely). I've tried swapping to my back-up fuel tank, same thing. I have an inline fuel filter between the fuel pumps and carbs. The first time this happened I looked and the filter was only half full of fuel. On closser inspection I noticed I had the filter up side down. Hooked up right (IN and Out) but the "out" was on top. With the motor running you could give it some throttle and the fuel level in the filter would go down. Let off and it would come backup. So I mounted the filter right side up. Now it stays full of fuel. Again ran it on the muffs, even goosed it a couple of times. Filter stayed full. Get to the lake. Same thing. After about 15 min of tubing it starts dieing back. At one point it died completly. Hit the primer bulb a couple of times, it fired right back up. This time the fuel filter was full but it looked like it had an air bubble on the inside of the filter element. I've had the fuel pumps apart and eveything looks good. Any ideas. Do I need to rebiuld the fuel pumps, or is it something I'm missing? Any help would be great. Tried to find a picture of the filter for clearification but no good. Basiclly its a glass tube with a filter inside.

 

[bktheking]

Re: Fuel problem. I think.

You sure it's fuel and not ignition? If I were you i'd be throwing an inductive timing light on the wires when it does it to see if you are losing a bank of cylinders. Have you pulled the plugs to inspect condition? What about cooling, is the motor temp perfect? Running on muffs doesn't mean a whole lot, tells you the motor runs but you can't really replicate running it in a lake @ 5500 rpm- heat, backpressure, load, none of it plays a part running on muffs, gonna have to be a lake diagnosis.

 

[rlb9844]

Re: Fuel problem. I think.

I had considered ignition, but it just seems like fuel to me. No, I have not checked the plugs. As far as temp. I don't have a temp gauge, just overheat alarm. The main reason I'm thinking fuel is like I said the one time it died I hit the primer bulb and she fired right back up. Also when it dies back, you can pull back to neutral and idel for 30 sec or so and go again for a little bit. Its like the fuel pumps can't keep up at high RPMs under load. I will try the timing light out the next time I go to the lake just to be sure. Thanks alot, and I'll keep you posted.

 

[emdsapmgr]

Re: Fuel problem. I think.

Possible the fuel pumps are weak. It is possible the carb bowls are running out of fuel. Next time you go out, try constantly priming the fuel hose bulb when you are running under load. This will force extra fuel around the pumps, directly into the carb bowls. If the engine runs fine while constantly priming the hose bulb, you may need to replace one or both pumps.

 

[rlb9844]

Re: Fuel problem. I think.

I took my boat out today. Tried the timing light first. Everything looks good. Next tried pumping the bulb. That helped but I had to squeeze the bulb really hard. With my wife driving I watched the inline filter. I'm pretty sure thats my problem. You can kind of see though the element and everytime the motor bogged down the inside of the element looked empty and the element looked crushed in. So here is my problem now. My tank has very small, looks like, rust particles in it. So small they go trough the screens in the fuel pumps so I need a filter of some kind. Can't get the tank out to clean it out. Will a water seperater catch these small pieces and still give the volume of fuel my motor needs?

 

[emdsapmgr]

Re: Fuel problem. I think.

Those 79's really did not have a good fuel filter when shipped from the factory. Sounds like you have installed a fuel line inline filter-good move. Pull the filter/screen off (the fuel pump inlet) and check it for debris. Before you invest in new pumps, make sure carb jets and the needle and seats have no errant rust particles in them that could block fuel flow. That includes the carb needle and seats. Make sure you are running a 3/8" fuel line from the tank to the engine. Also, make sure the tank anti-siphon ball valve moves easily and is not restricted by particles/debris.

 

[ltabel]

Re: Fuel problem. I think.

I have a 1979 140 hp evnrude that was having similar problems. I am by no means an expert but I discovered that the fuel line that runs from the connector to the fuel pump was bad. The line has a plastic coating on the inside and several pieces had come off and was blocking the fuel flow. I replaced the line and the motor is running GREAT now. I was like you I started with the carbs, fuel pump, and even pulled the gas tanks and cleaned them out. Once I replaced that fuel line all was good.

 

[Al-53]

Re: Fuel problem. I think.

Fuel lines would be a good start if they are original lines....I have seen old lines that have decayed inside and acted like a flapper valve...ethanol is a wonderful thing..lol...

Al

 

[rlb9844]

Re: Fuel problem. I think.

The carbs are clean, as well as the fuel pump screens. I replaced the line from the connector to the motor when I bought the boat about six months ago. The line from the tank to the connector is 3/8 copper. But what about the fuel/water seperator? Like an Attwood sold at Walmart. Will they catch dibris or just water? I have to take the inline filter out. It is the resriction. It will not allow enough volume of fuel to the carbs.

 

[Rick-va3rzs]

Re: Fuel problem. I think.

here is an idea .. go to your local parts store and ask for a high-flow filter .. like the type used in high HP car motors .. or anything that has F I that runs about 15 PSI

you will not get the 'see through' filter but it should solve your problem ..

I just added such to my jeep ( yea off topic) and works great

I hope this idea helps you out

 

[emdsapmgr]

Re: Fuel problem. I think.

You probably can add a cannister fuel water separator, but I'd double check the installation by teeing in a vacuum gauge, then test run it at top end. You need to be able to run the engine at top rpm with no more than 5-6 lbs of vacuum. The newer engines have a vacuum switch set to turn on the warning horn at 7 lbs vacuum-when the engine will start to run lean. Double check your feed hoses, they can kink when bent around corners when you install the new filter kit. Once you put a screw-on water separator in the fuel line, you need to eliminate any other inline filter. I eliminated the factory fuel connector on the lower cowling. Once you remove it, you can pull the supply hose through that hole and connect it directly to the hose barb on the upper fuel pump. FYI-Any original fuel hoses under the cowling were not made to handle today's ethanol fuels.

 

[rlb9844]

Re: Fuel problem. I think.

Thanks everyone for the advise. I'll install a fuel/water seperator and let yall know.

 

[Livewire]

Re: Fuel problem. I think.

FYI-Any original fuel hoses under the cowling were not made to handle today's ethanol fuels.

Are the replacement hoses that are available today (oem part numbers from Shop.Evinrude.com) suitable for today's ethanoal fuels?

 

[Al-53]

Re: Fuel problem. I think.

98% of the fuel lines today are ethanol resistant...I went to the Auto parts store to get some fuel line for my ATV and its says right on it...

the new OMC fuel line from tank to motor also says it on it....

Check Iboats for the lines...they may have it....if not try Napa...

Al

 

[wilde1j]

Re: Fuel problem. I think.

Your immediate problem appears to be a fuel delivery problem, which can have a number of causes, such as:
. air leak on pump suction side (bad clamp, cracked hose, cracked tank pickup tube, etc., etc.)
. malfunctioning anti-siphon valve
. plugged tank vent
. trash blocking tank pickup screen
. plugged fuel filter
. collapsed fuel line
. water or trash in internal and/or external filter
. try squeezing primer bulb or activating the choke/primer when RPM sag
. try an alternate fuel source (i.e. portable tank)

FUEL PUMP OUTPUT TEST

1) Pull the safety lanyard so the motor can't start
2) Disconnect the pump outlet hose
3) Crank engine ... should get long strong spurts, any less is reason to replace/rebuild

OR

Put a pressure gauge teed into pump outlet line ... should read ~ 3 to 6 psig on a good pump with engine running.

 

[curt660]

Re: Fuel problem. I think.

Look in the fuel tank to see if there is a filter on the pick-up tube? is it clogged?

There might be debris in the carbs, that while running down the lake will suck up into the high speed jets and then when you go back to idle or stop it the debris falls free.. I have seen this many times on a car.