The often repeated, stupid questions - car parts on the boat

I'm sure this has been covered. I tried a search, honest, but I guess my search criteria was lacking. And yes, I'm aware I'm about to ask what may be some really stupid questions, but I'm trying to find an actual answer other than just "They're different".
I have a 19' Bell Boy runabout, with a 140 I/O and a bow mounted fuel tank. The previous owner was 80-something and the boat sat for a long time. As such, it needs some parts.
The old metal tank was rusted, and has been replaced. I also need a fuel pump. I've heard the warnings about using automotive parts, but the warnings are generally lacking explaination. Plus, I'm generally suspicious of somone who wants to sell me a $120 fuel pump saying that I'll probably die if I use the $22 one.
All I could find regarding fuel pumps is that automotive quality pumps may leak all over the hot engine compartment when they go bad, whereas a marine grade pump will not. I guess they're saying that then engine compartment in my truck is not hot. Sounds like a bunch of hooie, but I'll buy it for now.
Since my tank is mounted in the bow, would I be risking life and limb by using a low pressure electric automotive pump mounted in the bow or along the side of the boat? It's nowhere near the engine compartment. Also, I've never seen an electric pump leak. They're sealed, generally, unlike mechanical pumps. Plus, I already have one and could save $120+.
Also, whats the real story on automotive vs. marine starters, and alternators? I need one of each. I know this is going to sound like I'm just trying to 'cheap out', but given that my boat seems to need all the expensive parts I really would like to save some money if possible.
Any advice other than "Just don't do it" would be appreciated.

Re: The often repeated, stupid questions - car parts on the boat

It's pretty simple really, marine parts are ignition proof, in your bilge you can possibly have a build of gas fumes and any spark can go boom. The mechanical fuel pump in a car can develop a leak or the diaphram can let go, what happens is it dumps fuel on the road, in the boat it would go into the bilge, with the marine one there should be a drain hose that runs up to the carb so if the pump ruptures it feeds the fuel right into the carb. Besides the big safety issue it's also illegal to use non marine stuff down there although that could be a mute point if it goes boom!

Re: The often repeated, stupid questions - car parts on the boat

Marine starters and alternators are marinized automotive starters and alternators. They have additional parts that prevent the sparks they make inside from igniting fuel vapors. Boats tend to trap vapors that just drift out of the bottom of vehicles naturally.

Mechanical fuel pumps have double diaphragms and are plumbed so that any leakage goes up to the carburetor where it can be burned rather than collect in the bilge where it can ignite. Marine electric fuel pumps are made mostly of brass and stainless steel. Car electric fuel pumps in boats rust and can leak gas into the bilge where it can ignite if they rust through.

Re: The often repeated, stupid questions - car parts on the boat

1st it is illegal to use non marine approved product in a boat, burns insurance doen't pay, someone injured will be living in your house, and driving your car. it's not whether they leak. it is the electrical situation. car parts are not sealed, in a boat gas fumes settle to the bottom, any arc from anything, can blow a boat ski high. beside your on the water, it's hard to just jump out when it starts burning, and running to a building to call the fire department. the regulations are there for a reason. your and my safety. your boat blow at the ramp, or dock, who else is going to get hurt. that why boat have blowers in the engine compartment, that you run for 4 to 5 minutes before starting, to evacuate the fumes.

Re: The often repeated, stupid questions - car parts on the boat

Well that covers that I guess. Thanks folks.
I guess my friends were right when they told me "a boat is just a hole in the water you throw money into". Seems that hole is in my yard though. Sometimes learning experiences suck.
Thanks again.

Re: The often repeated, stupid questions - car parts on the boat

Shop around for the parts you need online.You can get pretty good deals.
Send me a PM if you would like some links..

Re: The often repeated, stupid questions - car parts on the boat

lots of good replies... I have often wondered abt that myself. Understanding the fume and boom prospects... what about pts cond and distrb cap. I am running a similar set up and have gone both ways. I am also concerned because my distributer is old and has two screws or posts at 90* from the cap screws. They once had a rubber cap, and I wonder if there is supposed to be a rubber gasket, seal or o-ring that inhibits spark from getting between the base and cap?
sidenote: I used a qt of gas to burn some brush last weekend as I was out of kerosene. It's real exciting to play with !

Re: The often repeated, stupid questions - car parts on the boat

Also other than the whole it could blow your boat up, boat parts are specifically made (usally) to resist corrosion. Obvious reasons.

Re: The often repeated, stupid questions - car parts on the boat

Is the distributer marine? If so, it will have metal screen over any vent in the base, or a 90 degree nipple on the cap.

Re: The often repeated, stupid questions - car parts on the boat

( do we need a new thread? )
I bought the boat used, everything abt it at that time seemed to be marine. It is an '86 mercrusier I/O 120.
The distributer has not been off, I haven't looked for or seen ascreen over a vent on the bottom???? will check for vent.
The coil wire is a mercrusier part and it goes straight in, not at 90*
To describe the area I asked abt better: if the cap is off, the base of the distributer has a metal plate that the pts. and coil attach to. Near #1 wire location is one of the srews that fastens the cover, the other is 180* opposed to it's position. The rubber I had was on two screw in the base that are visable with the cap off on the outer edge of the plate, 90* to the position of the cap screws. I am wondering the purpose of the rubber caps and if they were once a larger gasket that sealed the cap?

Re: The often repeated, stupid questions - car parts on the boat

Here is a webpage that lists some differences in auto vs marine parts. Basically its all the same as what has been said, but it might be useful.

http://www.boatfix.com/how/marineeng.html