Help or I'm gonna sink my boat!

M

MercilessMike

Petty Officer 2nd Class
Joined
Jun 21, 2001
Messages
101
Sounds like fuel starvation or more likely, vapor lock ! But I will be curious as to what the experts say. Next time it dies, let it cool for a spell, then restart and see what ya get. :confused:
 
C

CHARGER 151

Cadet
Joined
Jul 22, 2001
Messages
19
Help or I'm gonna sink my boat!

Hey everyone....<br /><br />I am at wits end about my 1970 Volvo Penta AQ120. If I can't figure out what's wrong with this thing I'm gonna pull the plug and sink it!<br /><br />The engine is a 120hp 4cyl I/O with dual carbs on a 16ft 1970 Chrysler Charger 151. The past 3 weekends I have taken it out and it runs great for about 30 minutes and then dies without warning. There is no hesitation before it dies, it just dies.<br /><br />The first time this happened it was hard to start again after it died. However, once started it would run fine at 1000 rpms or less. If I attempted to give it more throtle it died. The carbs were supposedly rebuilt about two months ago right before I bought the boat from a service shop. I can see new gaskets in the carbs, so I believe that they indeed were rebuilt. <br /><br />To trouble shoot my problem I ran some tests on voltage and timing. I discovered that my coil was bad and my timing was off. I adjusted the timing and replaced the coil. I even added an in-line fuel filter to ensure no garbage was making it to my carbs.<br /><br />This past weekend I had my battery fully charged and took it out for another test run. It was the same story. She ran fine for about 30 minutes and then died. She started right back up and ran fine at 1000 rpms or lower, but would die if I gave it anymore throtle. <br /><br />If anyone has any ideas I would be forever greatful!
 
C

CHARGER 151

Cadet
Joined
Jul 22, 2001
Messages
19
Re: Help or I'm gonna sink my boat!

Mike,<br /><br />I haven't tried letting it cool and then restarting it the same day. But, I have taken it home and let it sit a day or so and then when I start it in the driveway, it runs fine?<br /><br />I'm at the point to where I'm going to take it to a service shop and let an expert look at it. If anyone has any ideas please let me know. I would like to have an idea of what it could be before I take to the shop.<br /><br />Thanks!
 
L

Liam

Petty Officer 3rd Class
Joined
Jul 8, 2001
Messages
86
Re: Help or I'm gonna sink my boat!

Don't do it!! I had a very similar problem with my little 60HP outboard. Changed everything and still died after 15 - 20 minutes. Yours probably runs great until it dies??<br /><br />Brought mine to an expert and he found the power pack to be faulty. This motor would rev fine with no load and then die down under load. Putting ears on it does not create a load. Changed the power pack and no problems since!! :D <br /><br />JB will probably teach you how to test the power pack to determine if it is breaking down when hot.<br /><br />Good luck and let us know what the fix is.<br /><br />Liam
 
S

sony2001

Chief Petty Officer
Joined
Mar 17, 2001
Messages
607
Re: Help or I'm gonna sink my boat!

condensor?<br />distributor cap?<br />distributor to coil lead?
 
C

CHARGER 151

Cadet
Joined
Jul 22, 2001
Messages
19
Re: Help or I'm gonna sink my boat!

Liam,<br /><br />I know I'm a newbie at boating, so don't laugh, but I have no idea what a power pack is??? Is this just a different name for something or perhaps just an outboard thing? Or, am I just really that unknowledgeable about engines? (Probably the latter)<br /><br />Sony,<br /><br />The distributer cap, rotor, and leads all seem to be good. If I pull the #1 plug off and hold it near the engine block and then start the engine I am seeing fire. <br /><br />Again, I'm new to boating and for the most parts engines too, so I'll go ahead and ask. Where is the condenser and what does it do?<br /><br />Thanks.
 
K

krosemond

Petty Officer 2nd Class
Joined
Apr 8, 2001
Messages
198
Re: Help or I'm gonna sink my boat!

Is your fuel tank vented properly. You could be creating a vac-key-ume that restricts fuel supply, and as air slowly seeps back in the tank, you can pull enough fuel to run at the lower rpms. Try taking you fuel cap off when this happens and see if you hear a swosh.
 
O

ODDD1

Lieutenant Junior Grade
Joined
Jan 23, 2001
Messages
1,054
Re: Help or I'm gonna sink my boat!

ATTA BOY. Krosemond...I"m readin down this post thinkin 'the tank isn't venting!' is the first thing I would check....
 
M

MercilessMike

Petty Officer 2nd Class
Joined
Jun 21, 2001
Messages
101
Re: Help or I'm gonna sink my boat!

Good Call K man and with ODD1 agreeing..Always the obvious which gets overlooked (speaking of myself of course)Hope he responds again with update on issue. Found that primer screw, waiting for key to arrive.....<br /><br />PS... alot of newbies, only dumb ? is 1 which does not get asked.
 
JB

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Help or I'm gonna sink my boat!

Ahoy, Charger. Be sure to sink it where it will provide shelter and structure for the fish. :D :D (JK)<br /><br />Red sky at night. . .<br />JB :)
 
C

CHARGER 151

Cadet
Joined
Jul 22, 2001
Messages
19
Re: Help or I'm gonna sink my boat!

Thanks for all of the great ideas. I appreciate the help.<br /><br />As far as venting the fuel tank goes, should there be some sort of vent on the tank? If so, should I be looking to see if this vent is closed? A friend of mine had actually suggested that my problem might be because of an improperly vented fuel tank, but decided against that when I told him that I did have an overfill hose coming from the tank. I'm sure that this hose isn't clogged becasue it spewed all over me the last time I filled the tank.<br /><br />I was thinking of buying a portable tank to take out on the boat this weekend. I figured I would run the boat from the regular tank first until the engine dies. Then I would hook up the portable to the fuel pump, bypassing the regular tank and fuel line. If the boat runs then I would know for sure that my problem lies in the fuel tank.<br /><br />How does that sound? If anyone can think of a better way to touble shoot this venting problem I would love to hear it.<br /><br />Thanks!
 
W

Walter

Senior Chief Petty Officer
Joined
Jul 3, 2001
Messages
787
Re: Help or I'm gonna sink my boat!

It's been my experience that when an engine is fuel starved, it usually doesn't abruptly shut off as if the key switch was turned off. They'll chug, miss, cough, sputter, chatter (what other adjectives can you guys come up with?) before they stop running. This isn't always the case...but often this holds true. What you are describing with the remote fuel tank sounds like a good idea... Be careful of spilling fuel as you swap from one to the other... However, from how you describe your engine is shutting down...I'm not convinced your problem is fuel related. <br /><br />Walt
 
B

Beernutz

Petty Officer 1st Class
Joined
Aug 14, 2001
Messages
287
Re: Help or I'm gonna sink my boat!

A lot of good suggestions.<br /><br />I'd like to add one more. Texas..... Humidity. Have you checked for water in your fuel? A little "dry-gas" (or alchohol) should solve that problem.<br /><br />Your low speed jets draw fuel from the upper portion of the floatbowl. When you hit the throttle, she changes over to the main jet, which draws from the bottom, where the water lies.<br /><br />Might be worth a try.<br /><br />You don't have a power pack.
 
C

CHARGER 151

Cadet
Joined
Jul 22, 2001
Messages
19
Re: Help or I'm gonna sink my boat!

Thanks Beernutz.<br /><br />I didn't think I had a power pack on there. As far as water or condensation goes, I did pour in some Iso Heet water remover when this first happened thinking that could be the problem. Unfortunately, that didn't solve my problem. <br /><br />I was just speaking to a guy a work about this delima. He said that if the overflow hose from my gas tank was spewing as it did, then my tank should be properly vented as the overflow hose acts as the vent. If he's right, then I'm back to square one....ready to sink my boat!<br /><br />He suggested that shop that rebuilt the carbs may have not set the floats correctly. However, I ponited out that the boat runs fine for about 30 minutes. Therefore, the float theory couldn't work because if that were the cause the boat would have died after 5 or 10 minutes when the bowls ran dry.
 
B

Beernutz

Petty Officer 1st Class
Joined
Aug 14, 2001
Messages
287
Re: Help or I'm gonna sink my boat!

You're getting good information there. Doesn't sound like it's your tank vent, either.<br /><br />Most tanks have a screen or filter at the bottom of the pickup tube. I've seen these clog, causing fuel starvation. Pretty tough to get to in most applications, though.<br /><br />I think you have the right idea. Try the portable tank, and eliminate the possible sources one at a time. Otherwise, I gotta go with J.B.
 
L

Liam

Petty Officer 3rd Class
Joined
Jul 8, 2001
Messages
86
Re: Help or I'm gonna sink my boat!

No powerpack eh? The symptoms and the previous testing done leads me to believe that this is not fuel related but electrical. Try this, the next time it dies out restart it and see if it will go. If it wont go take it out of gear and see if you can get higher revs without load. If you can, then put it back under load and begin removing spark plug wires. If the motor dies when you remove a wire that is a good firing cylinder. That will tell you which cylinders are affected.<br /><br />This must be done under load and when the symptoms are evident. Please hold onto something in case she decides to rev up and go!!<br /><br />Liam
 
T

TONY H

Petty Officer 2nd Class
Joined
Jul 2, 2001
Messages
115
Re: Help or I'm gonna sink my boat!

Look for the vent on the outside of you hull it should be a small chrome thing Looks like a nose. It will have a hole facing the water.<br /><br />I wonder if you have something semi floating in your gas tank that finally gets sucked into you fuel tanks line. when the boat shuts down, the objects moves away from the Fuel line. Can you run a separate tank directly to your Carbs. take it out for a spin and see what happens. If it stalls then at least you know it's not your fuel tank or it's fuel lines.<br />Good luck
 
R

rwise

Captain
Joined
Jul 5, 2001
Messages
3,205
Re: Help or I'm gonna sink my boat!

This sound a lot like something I did in my younger days, toke a grape leaf and rolled it up put it in the end of a hose and pushed hose into tank then blew leaf out! They never found the problem, man I almost feel guilty about it know. Gives the symptoms of runs then dies, starts back up after setting and runs tell leaf clogs intake line again. As long as it was in gas it would remain soft. Ok I have grown out of stuff like that. The extra tank idea is sound! Also is the engine hot more than normal?<br /><br />Richard
 
B

Bluefish

Petty Officer 2nd Class
Joined
Mar 14, 2001
Messages
125
Re: Help or I'm gonna sink my boat!

Hey CHARGER 151 just two things you mighty want to keep in mine about your fuel tank,One when you over filled the tank and got fuel out of the vent if the hose has any low spot in the rounting you could have fuel sitting there and causeing you to get poor venting, Two if you have a broken pickup tube in the tank,you could be sucking up air when the fuel level gets low and your not on plane.<br />Good Luck
 
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