what is happening when....

bob johnson

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Feb 25, 2009
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lately my motor will start ok...and I am off and running, but about 5 minutes or so out...the motor starts to stutter and dies...

I go check the bulb and it is weak...so i pump it back up... and she fires up and we are off...and it doesnt happen again..

happens each time i start up after a long off spell.

not the end of the world

lots of gas in the tank

the vent is open

the tank is way up front...I have a bulb up at the tank and one right before the engine..i have a seperator 2 feet before the last bulb...

I have a two way valve up front as well to feed off one of two tanks, one at a time...


this issue wasnt prevelant earlier this summer..


could I have debris in the tank maybe???

it only does it once on each start after a long time of not running( longer than maybe 30 minutes)

I didnt try to pump the bulb when it started to happen..

I did once put it in nuetral and try to rev it..and it still dies...

so it isnt a cold issue...seems to be a fuel flow....

thanks


bob
 

jtexas

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Oct 13, 2003
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8,646
Re: what is happening when....

What motor we talkin bout here?

Why 2 bulbs? you ought to be able to prime the line just fine with just the one, close to the tank.

What's happening is, it's taking about 30 minutes for the pressure in the fuel line to bleed down, whereas it should take more like 30 hours. you're left with just the fuel in the carbs, and whatever the pump can bring in before it completely looses prime.

There's a lot of connections there for it to draw air from.
 

bob johnson

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Re: what is happening when....

I hadnt thought the model of the motor would matter...but I could be wrong

I was thinking its in the system, not the motor itself..

but anyway 1995 115 ocean runner..

two bulbs because it is about 16 feet tank to motor and normally I only prime the back bulb, but when i switch tanks, I prime the new tank( actually there are three bulbs!!! one right next to each tank and one at the motor...

I could check the connections...but since it doesnt happen the rest of the day!!!!!!!!!!!!!!!!!! hour and hours...i figured it wasnt a defect like that


thanks

bob
 

bob johnson

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Re: what is happening when....

I was only pulling gas from the port tank... this past weekend...

Ill have to check and see if the same thing happens with the starboard tank

I have 9 gallon portables up under the front deck..one on each side...running 3/8th" IS quality gas line...but they do have hose clamps on the connections and they have the OMC quick disconnects on the end to connect to each tank...so i can pull the tank and replace at any time...


bob
 

jtexas

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Re: what is happening when....

model might not matter...bigger motors suck up fuel faster, some differences in pumps....

little confusion here...
it only does it once on each start after a long time of not running (longer than maybe 30 minutes)

I read that to mean each start after at least a half-hour down time.

But then you said
...it doesnt happen the rest of the day!!!!!!!!!!!!!!!!!! hour and hours...


Guess I'm missing something -- when you prime one bulb until it's firm, the other bulb has to be firm too, right? I mean when the fuel line is pressurized, all the bulbs on the line have to be firm, otherwise there's no pressure.

I can't think of why the length of the hose would make a difference, but I'm not an engineer or anything.

Interestingly, I had a very slight gas leak from my primer bulb connection to the hose, not enough to cause performance issues, just enough I could smell it, and see it when I looked close. I replace the OEM clamp with a hose clamp (smallest I could find) but could not get it tight enough to hold -- guess the clamp was too big. I replaced that with two cable ties -- did the trick. One probably woulda worked, I just put two on for good measure.
 

bob johnson

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Re: what is happening when....

well when I said it doesnt do it again, I ment if I dont turn the motor off for a long time ....it doesnt happen...so If I run the motor continuously it runs great..or if i shut it down and start in a few minutes it doesnt happen...it has only done it the past two weekends...

so i dont have lots of incidents to speak of...

normally I just squeeze the bulb by the motor....
tomorrow Ill run the motor and squeeze the bulb before I think it will happen...see if that pre empts it...

I wont be using much gas tomorrow so i have to wait till another time to try the other tank...which is empty now....unless I gas up at lunch tomorrow..

the issue I have a hard time getting around....is it is new...




bob
 

jtexas

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Re: what is happening when....

well when I said it doesnt do it again, I ment if I dont turn the motor off for a long time ....it doesnt happen...so If I run the motor continuously it runs great..or if i shut it down and start in a few minutes it doesnt happen...

ok I see, sorry I was a bit dense there...it's just a very slow leak, the fuel pump has no problem repressurizing the line after a short stop, and keeping it pressurized, but when it's not running it bleeds down more quickly than normal. Hose connectors, quick disconnects, etc., they wear out gradually.

Nobody's fuel line is 100% air-tight; if it were, we could pump the bulb up once, then not again until the tank ran dry, no matter how many weeks or months it takes. I've had camping trips where I pressurized the line on day one and it held for a couple or three days (with lots of use each day and usually some at night too). Other times, I've had to pump it up the next morning.

But when it gets to where it doesn't hold for a full day of fishing (no matter how long I stay in one place), that's when I take action.
 

bob johnson

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Re: what is happening when....

ok I see, sorry I was a bit dense there...it's just a very slow leak, the fuel pump has no problem repressurizing the line after a short stop, and keeping it pressurized, but when it's not running it bleeds down more quickly than normal. Hose connectors, quick disconnects, etc., they wear out gradually.

Nobody's fuel line is 100% air-tight; if it were, we could pump the bulb up once, then not again until the tank ran dry, no matter how many weeks or months it takes. I've had camping trips where I pressurized the line on day one and it held for a couple or three days (with lots of use each day and usually some at night too). Other times, I've had to pump it up the next morning.

But when it gets to where it doesn't hold for a full day of fishing (no matter how long I stay in one place), that's when I take action.



ok I recently rebuilt one of the carbs, and too some gas line off....

everything ran great after I put it back together...better than ever, but I didnt run it much afterwards...

I will look again closely at all my connections

thanks for helping

bob
 
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