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all blown up

  • Karma: +0/-0
Engine starts then quits
« on: June 25, 2009, 06:11:22 PM »
this past weekend after a short bumby ride in parker and an hour later when i went to start her back up, the engine started fine then after roughly two sec. would starved out, this repeated several times.  I finally got it started but you could tell that the engine wanted to keep quiting with out giving her some gas it would of but it seemed to be ok so i trolled around for a bit to see what happens, then for a ride (about 15 min long). shut her down to jump in the water waited about 8 min tryed to start her up and had the same outcome.  Finally after getting back to the beach waited awhile but could not get it to start again. Any Ideas this happened so suddenly.  Boat was running great just had it in the water a week before and no signs of issues then.  I thought maybe the floats in the carbs might be stuck, if so could this cause this to happen, any ideas? Engine BBC with blower, Holly Carbs (engine is 3 yrs old)
Thanks
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obnoxious001

  • Karma: +4/-1
Re: Engine starts then quits
« Reply #1 on: June 26, 2009, 11:06:53 PM »
It may be starving for fuel, but pumping the accelerator activates the accelerator pumps on the carbs, keeping it running a bit.

Try checking the fuel filter, fixed one like that at the sandbar a few weeks ago for a younger guy with a jet boat.  PM if you have more questions about it in case I don't get back to this thread.
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GT Jets

  • Karma: +192/-0
Re: Engine starts then quits
« Reply #2 on: June 27, 2009, 11:26:22 AM »
Vapor lock? are your tanks vented?.

What kind of fuel filter do you have? Steel tanks (rust)?

A fuel pressure gauge will answer a bunch of questions....

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

all blown up

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Re: Engine starts then quits
« Reply #3 on: June 27, 2009, 12:41:22 PM »
1. Vapor lock? Im not sure what that is and where to look?

2. are your tanks vented?.  I think through the gas caps?

3. What kind of fuel filter do you have? The only fuel filter is the filter/ water seperator, one on each tank, and i changed them when this started did not help.

4. Steel tanks (rust)? As far as the tanks im not sure they are fiberglassed in and i cant see them.
Thanks
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  • Karma: +192/-0
Re: Engine starts then quits
« Reply #4 on: June 27, 2009, 01:18:36 PM »
Vapor lock is what happens when the fuel is either too hot to pump because it literally boils in the fuel hose on the suction side of the fuel pump, or due to a restrictive fuel pickup or other type of restriction. The lower the suction pressure of the inlet fuel hose, the easier the fuel boils, that is where the term "vapor lock" comes from. Pumps are positive displacement and cannot very effectivley pump vapor.

The simplest way to prove this would be with a fuel pressure gauge.

You reaal need to know what the fuel pressure is to be able to determine where the problem is.

IMHO that would be the first step.......

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

all blown up

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Re: Engine starts then quits
« Reply #5 on: June 27, 2009, 08:05:54 PM »
can you get that guage at a local auto store?
And thanks
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  • Karma: +192/-0
Re: Engine starts then quits
« Reply #6 on: June 27, 2009, 08:15:46 PM »
can you get that guage at a local auto store?
And thanks

You can go either way, but yeah, auto parts store should be able to help you out..it does not have to be permanent, but is nice to have.

For the closed engine troubleshooting I have used an electric outboard water pressure gauge and a tee in the fuel hose, works bitchen.

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

all blown up

  • Karma: +0/-0
Re: Engine starts then quits
« Reply #7 on: June 28, 2009, 08:04:31 AM »
I will get a meter this week and let you know what happens. 8)
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all blown up

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Re: Engine starts then quits
« Reply #8 on: June 28, 2009, 08:36:55 AM »
What sould the pressure be at idle, 2,000, 3,000, 4,000 rpm. is 5 psi ok at idel, or does it need to be higher
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Re: Engine starts then quits
« Reply #9 on: June 28, 2009, 11:25:05 AM »
What sould the pressure be at idle, 2,000, 3,000, 4,000 rpm. is 5 psi ok at idel, or does it need to be higher

I run 7 PSI (regulated electric deal), but IMHO 5-7 should do the job, higher pressure for smaller fuel lines (more flow).

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Nordie

  • Karma: +13/-0
Re: Engine starts then quits
« Reply #10 on: June 28, 2009, 12:17:50 PM »
i run about 6 at idle! 3/8 fuel line
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If im not posting..I'm pooping!

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Re: Engine starts then quits
« Reply #11 on: June 28, 2009, 08:51:46 PM »
OK THANKS
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obnoxious001

  • Karma: +4/-1
Re: Engine starts then quits
« Reply #12 on: June 29, 2009, 12:23:44 AM »
I will step in and say that although it will run with 5-6 lbs fuel pressure at idle, I would want more than that since you stated it's a blown engine. 

Furthermore, I would personally like to see you have a fuel pressure gauge in the dash, since if your fuel pressure drops while you are running it hard, there is a good chance you will do some serious damage to the engine from leaning it out.

You need to keep pressure under 10 lbs at idle so you won't be forcing gas past the needle and seat, but I would think no less than 7 lbs of pressure. 

If you need some help sorting it out, I am somewhat of a drive, but will look at it free for you.
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electrowoman

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Re: Engine starts then quits
« Reply #13 on: June 30, 2009, 03:48:31 AM »
How about the fuel pump loosing it's prime.   Bad pump is my guess.
If it sat long enough to cool I'd rule out the vapor lock.
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all blown up

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Re: Engine starts then quits
« Reply #14 on: June 30, 2009, 05:39:23 PM »
obnoxious001, i sent you a P.M.
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obnoxious001

  • Karma: +4/-1
Re: Engine starts then quits
« Reply #15 on: July 03, 2009, 02:04:58 PM »
Well, Sean brought the boat by today so I could look at it with him.  He has an electric Holley pump, fuel pressure gauge on the dash, and one float set slightly too high so it was dumping fuel as soon as the key was on.  He didn't have a hose adapter for it, and I don't typically work on boats here, so we fired it just once for two seconds to make sure it would fire right up.  I pointed out some cracked vacuum caps that need replacing, and we also discussed a bunch of modifications that he can do to plumbing as money allows, and worked on a couple of blower guard brackets that were touching the blower belt.  Sent him off to Rex Marine with a parts list to replace a funky looking fuel line to his fuel log, after spotting a cracked aluminum fitting that would have left him stranded somewhere.  It is jet ski day at Puddingstone, so no easy way to test it close by today, will have a full report after it runs someplace.
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