Engine Starts and Dies within seconds

hudsonoffice

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Apr 14, 2017
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I have a 1998 Larson with a Volvo Penta 5.7gs in it. I had the carb rebuilt at a carb shop a couple weeks ago and just put back on boat and now I am pulling from winter storage. If I give it a couple pumps of gas it fires right up and dies. I tried this a few times and same results. I admit I did not fill tank up with fuel before storage so I am wondering if it is a water issue or could there be something else? It ran fine before I put away and fogged/winterized it.

Any help is greatly appreciated.

PS. I had it rebuilt because it started and died after a minute or two last year also when you hammered it down it fell flat and had to back off and slowly throttle up.

Hudson
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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welcome aboard

your PS description is classic accelerator pump failure

your issue would not be a water issue, because it wouldnt fire at all on water

lets make sure that the start and die is same, or is it electrical. do your gauges still function? if yes, then we can rule out a bad ignition switch
does the motor die as soon as you let off the key, or does it run for a short bit? if it dies the moment you let off the key, its ignition power related
if it dies a short bit after, its fuel related. could be plugged idle circuit
 

alldodge

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Howdy

Need to start with the basics,
Check fuel filter - , see if its full, then pour contents into something clear to see if there is water (plastic bag, jar, other)
Check if your fuel pump is running - guessing an electric pump
 

hudsonoffice

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So to clarify a bit. I did tonight pull fuel filter and drain. It was not to bad. I did replace Filter anyway I do every year. All gauges work including oil pressure. I can rev it up to say 1100 RPM and will stay running. The accelerator pump was replaced with the rebuild kit.
If I don't mess with RPM it starts and dies within a second or two.
If I don't pump gas it has a bit of a extended crank then starts and dies.
 

89retta

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I'm thinking a problem with the fuel pump. Check that first
 

Augoose

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Spray some carb cleaner around the base of the carb and listen for the rpm's to rise - sounds like you may have a leak.
 

hudsonoffice

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Apr 14, 2017
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Well the fuel pump does pump fuel when cranking I took line off and it pumps.
I replaced pump anyway since it's almost 20 years old. No change starts and dies.
I sprayed carb base while it did idle for the few seconds. No Change
I put mixture screws all the way in and backed out 1 3/4 turns No Change.
I unscrewed 1/2 more and tightened in. No Changes

So only 2 options I am thinking is take back to get rebuilt, but would like to know what you carb guys think could be issue?
2 option is to run carb on spray and make sure fuel is still pumping without cranking.
 

alldodge

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If the motor dies right after it starts, then its not the carb. The carb would be full of fuel and would run for some time before it is all used up. The only way it could be the carb is IF the idle circuit (jets) are clogged solid. The carb gets a shot of gas from the accelerator pump, engine starts and then dies almost immediately.

Otherwise if the motor starts and dies as soon as the key is released, then this is electrical. Would look for 12V at the + side of the coil and see if it gone when key is released.
 

alldodge

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It will run for about 4-5 secs after. If I spray with carb spray she keeps running

Your carb idle circuits are clogged up. The 4 to 5 seconds is it burning off the gas pumped in by the accelerator pump would be my guess

Will it keep running if you keep pumping the throttle some?

Oh and hope the carb spray is not either, that stuff can damage the motor after some time
 

alldodge

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If it was just rebuilt by a pro carb shop what could they have missed to cause this issue?

My first guess is actually cleaning the carb. Just because there name has "Pro" in it, means nothing. A carb is a pretty simple device. It uses small passages to allow fuel to pass under low speeds and high vacuum. Once above 1500 rpm's or so the main jets start getting used and the idle passages mostly stop.
 

hudsonoffice

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Apr 14, 2017
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Well team I pulled carb off and pulled apart. Found 1 of the new gaskets from the rebuild needed to be modified. I reinstalled and it purrs like a kitten. Bottom line was idle circuits were plugged by gasket.
I appreciate all the suggestions.
 
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