flooding?

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bayliner12

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I have a 1991 120 H.P L drive, initally it will start right up, i have to keep the RPMs up for a little while or it will die, after about a minute the RPMs will JUMP up and then it will idle fine, I'll turn it off and let it sit for a while, when i go to restart it wont and i can smell fuel, I'm guessing somehow fuel is leaking back into the cylinders? once it does start it runs great at idle at speed, everything is great, it's just tough to restart after a shut down
 
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john from md

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Re: flooding?

You can have plugged orfices in your recovery system and/or you may have holes in your fuel pump diaphram or your carbs may not be shutting off the fuel for several reasons.

1. Have the carbs ever been rebuilt? Has your linkage every been adjusted?
2. Have you ever changed your fuel pump diaphram?
3. Do you do a decarb regularly or at all?
4. Do you know what your compression numbers are?
5. Do you winterize the engine in the off season?


We need more data in order to tell you what to do.

John
 
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bayliner12

Petty Officer 2nd Class
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Messages
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Re: flooding?

o.k lets see if i can answers these
1.carbs were rebuilt about 10 years ago, i didn't see any reason to do it again because it runs so well, only a problem at restart
2. haven't changed diaphram, was going to do that tomorrow
3. haven't decarbed in a couple years, the boat has only been used maybe a dozen times in the last 2 years, i do start it a couple times a month jsut to keep everything cosher
4. checked the compression last week, 140 all cyliners within 2 lbs of each other
5. the boat did sit most of the winter without stabilizer, but like i said i start it quite regularly, i did put satbilizer in it when i knew i wouldnt be able to start it for a few weeks.

thanks for your reply
 
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john from md

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Re: flooding?

Due to the makeup of today's fuels, you will have to change your way of thinking if you want your boat to keep running year after year.

Today's fuels do the following. 1) break down faster, damage rubber and fiberglass, cause growth in fuel cells, absorb more water and experience phase separation.

Boat engines suffer more from today's fuel problems as they are not used constantly. You probably have build up in your carbs that is causing restricted jets and that is why your engine is sporatic. You may also have material from your fuel pump diaphram.

Additionally, with the new fuels breaking down rubber, most of us put a fuel filter between the fuel pump and the carbs so that the material does not get to the carbs to stop them up.

I know an L head is harder to work on that a straight outboard but I suggest tearing down those carbs and adding a fuel filter.

John

Pardon the lecture, it has something to do with getting old.
 
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bayliner12

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Re: flooding?

i too john am old so dont worry about any lecture, do you think decarb will help? the only L drive mechanic in town wants $600 to rebuild the carbs, i have a good mechanical background so i dont have a problem with rebuild. i am a little leary about synchronizing though.
 
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john from md

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2,184
Re: flooding?

Try this.

First, change that fuel pump and add a cheap plastic fuel filter in the line from the pump to the carbs.

Buy Deep Creep spray from an auto or boat store. This is Seafoam in a spray form. Spray each carb through the bowl vent until you think you have a good bit in the bowl. The bowl vent is a little brass fitting with a hole in it that sits on the side of the carbs.

Let this sit for a day or so. Next prepare a gallon of decarb mix per the FAQ instructions. Do the decarb letting it sit a full 20 to 30 minutes between doses.

If this doesn't work, then you have to pull the carbs apart. I can walk you through the linc and sync with no sweat.

Let me know how it works out.

John
 
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bayliner12

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Re: flooding?

i have the clymer and force out board survice manual, i dont see the the bowl vent?
 
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john from md

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Re: flooding?

You won't see it in a schematic, you have to look at the carb. They are located on the side of the top half of the carb. Which side I can't tell you as I am at work and need to look at the carb to tell. It looks like a small brass piece with a hole in it. All carbs have a bowl vent to equalized the pressure during operation.

Try looking on the right side of the carb as you are looking at it. I seem to remember that it is on the same side as the fuel inlet pipes.

John
 
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bayliner12

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Re: flooding?

should i drain the fuel from the bowls? i bought a pump rebuild ki, it came with a diaphram and a couple gaskets, is that all it should have?
 
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john from md

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Re: flooding?

No, you don't have to drain the bowls. Just have a rag to catch the fuel when you disconnect the lines. There are three lines on the pump. An inlet, an outlet to the carbs and one air impulse line that goes to the block. The inlet and outlet have fuel in them. Pull them off, then remove the six screws from the pump cover and remove it. The pump diaphram and gasket are all that is usually changed.

John
 
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bayliner12

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Re: flooding?

what i ment was do i need to drain the bowls when i spray the decarb into the bowl vent
Tim
 
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john from md

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Re: flooding?

No, it will disolve any varnish and it will start to get diluted as soon as the flywheel starts to rotate so it won't cause oil starvation.

John
 
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bayliner12

Petty Officer 2nd Class
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Re: flooding?

o.k. i'm going to give it a shot, probably tomorrow if it cools down, i bought 2 cans of quick silver, a kit for the fuel pump, fuel filter, and plugs, anything else you recommend?
Tim
 
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bayliner12

Petty Officer 2nd Class
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Messages
145
Re: flooding?

i tried finding the vent but no luck, i tried everything that looked like a possibility but none would accept the spray
 
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bayliner12

Petty Officer 2nd Class
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Messages
145
Re: flooding?

it was an interesting day to say the least, my wife was parking the truck after my daughter and i launched the boat, she started yelling something about a crash, i thought someone hit my truck, then she pointed up at a helicopter flying over us smoking, it went over us and crashed just beyond, she went up and got the rangers and they went to the crash site, apparently no one was hurt...except the helicopter, any way the boat stated right up ran great, came out of the hole better than it ever has, got to our site got set up went to restart, just cranked, let it sit for about 20 minutes, started right up, then the darn thing wouldnt go into gear, i could feel under water that the cable was sliding through the clamp, got towed back...thought of it as a limo ride...i'm thinking i must of forgot to tighten the screw on that clamp, i still cant figure out the re starting problem.
 
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