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egnition fuse blowing

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searay91

New member
Have a 1991 searay with 4.3 mercruiser , alpha1 drive, keep blowing the ignition fuse [20 amp under the dash] , used to start ok then run using the muffs, increased the rpm , was ok ,let off on the throttle
then it would die.
Now as soon as I turn the key to run only the fuse goes + my nav light fuse to.
This past summer I forgot to put the plug in , got some water in the hull , but still started after draining , + did the mistake of starting it offshore without water supply for a few minutes :(, could I have
ruined something? , it looked like I was overheating when I got back to dock.
 
Running the engine for more than a few seconds, i.e. 3 to 5, can and will trash the raw water pump impeller which is neoprene and depends on water flow to lubricate the vanes and stop them from self destructing. When you open the pump, you may find that pieces of the impeller are missing. Try to find them as they often end up lodged in inconvenient places and cause problems.

Inso far as your fuse problem is concerned, finding the problem will be a process of elimination, i.e., buy a box of fuses. Is your ignition electronic or mechanical points.
 
sandkicker said:
Running the engine for more than a few seconds, i.e. 3 to 5, can and will trash the raw water pump impeller which is neoprene and depends on water flow to lubricate the vanes and stop them from self destructing. When you open the pump, you may find that pieces of the impeller are missing. Try to find them as they often end up lodged in inconvenient places and cause problems.

Inso far as your fuse problem is concerned, finding the problem will be a process of elimination, i.e., buy a box of fuses. Is your ignition electronic or mechanical points.
Click to expand...

Thanks for the info , im sure I ruined the impeller, is there a overhaul kit to replace it? seals & whatever else? , want to be sure as the motor did overheat im sure.
as for the ignition it is a thunderbolt IV HEI.
 
tHERE is a car stereo , but I dont think thats the problem, question, should the engine start when the throttle is moved forward in just engine mode?
, or does it have to be in nuetral? , would it be a neutral safety switch?
 
Has to be in "engine only" mode, in Neutral. Position of throttle in "engine only" mode won't prevent engine from cranking/starting.

Re: pump... there is a standard kit available. Usually not required to replace seal, just impeller.

Fuse blowing. Start by disconnecting the Thunderbolt control box.... not the lead from there to the distributor.
 
Has to be in "engine only" mode, in Neutral. Position of throttle in "engine only" mode won't prevent engine from cranking/starting.

Re: pump... there is a standard kit available.

Fuse blowing. Start by disconnecting the Thunderbolt control box.... not the lead from there to the distributor.
 
searay91 said:
Just drained the stern drive , oil is a very light brown/ tan color, slow coming out, do you think I have A seal problem?
Click to expand...

Probably... pressure test as recommended in previous post to find out ifso and where. Check for leaks (soapy water) prop shaft seal first.
Also... re: slow coming out. ... possibly wrong lube in drive.
 
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searay91 said:
Just drained the stern drive , oil is a very light brown/ tan color, slow coming out, do you think I have A seal problem?
Click to expand...

No you do not most likely have a problem with your gear oil.........Water in the gear oil will make it milky after running and if it sits for a while then water will come out first when the plug is removed.............bet you did not remove the upper screw in the upper gear housing. That would explain the slow draining.

If you are replacing the impeller make sure when you get it back together you fill from the bottom untill it comes out the vent (top (side) screw, on passenger side of upper gear case)

As far as your ingintion fuse blowing,

Reasons for blowing a fuse:

1...to high a current draw based on fuse rating........What amperage fuse is the one blowing.should be 20 amp.
2. a short to ground somewhere on the ignition run circiut..........Puprle wire leaving the ignition switch.



The only way to troubleshoot is to find all puprle wire connections under the dash and remove one at a time to see which one causes issue.

if that does not solve the issue then it may be at the engine and a wire is getting shorted out......not easy to diagnose from here...
 
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