351 mustang motor inboard won’t start when warm

Ellington

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Aug 19, 2021
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I have an 87 supra with a 351 mustang motor that will only start once a day. I have started it at 9 am every morning for 3 days straight, but at 5 pm, it will not start. One time I accidentally hit the throttle only switch in while pumping the throttle, and it fired. Since then, when it won’t start in neutral, there has been times where it starts after putting it in gear. None of this makes any sense to me!!!
 

Bondo

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Ayuh,..... Welcome Aboard,...... Does it not turn over on the starter, or does turn over, but don't start,..??
 

Ellington

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Aug 19, 2021
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It turns over but won’t fire, also if I hold the key for about 4 second intervals while pumping carb, both batteries will die after 5-6 no starts. That is extremely odd too right?
 

Bondo

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Ayuh,.... Sounds like weak or dyin' batteries, or extremely corroded connections,.....
Does it start after pumpin' the throttle,..??
If so, it sounds like a fuel delivery issue,.....

What outdrive, or other drive is this,..??
 

Ellington

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Aug 19, 2021
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brand new batteries and starter this year, it will only start by pumping throttle, fuel pump was going to be my next step, except it starts when it gear more often then when I have the throttle only switch engaged. It is a ski boat, so centre engine with a shaft down to a prop and rudder.
 

Bondo

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brand new batteries and starter this year, it will only start by pumping throttle, fuel pump was going to be my next step, except it starts when it gear more often then when I have the throttle only switch engaged. It is a ski boat, so centre engine with a shaft down to a prop and rudder.
Ayuh,..... When the batteries were installed, were the wirin' ends rubbed with sandpaper,..??
How 'bout at the starter,..?? Ground connections,....

Check the contents of whatever fuel filters ya got,.....
Pull the gas line off the carb, direct it into a catchcan, 'n roll the motor over on the starter,....
There should be a full flow of gas,....
It could be the carb itself too,....

As for the starter crankin' over, In Gear,.....
There's a neutral safety switch somewhere, 'n yer's ain't workin',.....
Generally speakin', it's in the control, with yellow/ red wires,....
Yer's could be somewhere along the shifting linkages,....
 
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