Re: Switching from mechanical fuel pump to electric??
 

You say "1994 454 mags" is this happening on both engines?

Re: Switching from mechanical fuel pump to electric??
 

That is correct, it is happening on both motors. When they are cold, we have to pump the hell out of them to get them started, hate hearing them crank and crank until we finally get a sputter and finally startup. Once running, they are perfect for the rest of the day. No other complaint other than starting the dammed things....

Re: Switching from mechanical fuel pump to electric??
 

Bad accelerator pumps? Is the choke working? The carb has fuel in at start-up. Needs absolutely no fuel presure to start an engine. So, either you are somehow loosing fuel out of your fuel bowls, or you have a bad accelerator pump. What carbs you got?

Do this - with the engine off, remove the flame arrestor. Open the choke. Look down the carburetor. Have someone move the throttle to full throttle. As it moves, you should see gas squirt in. If not - you have a bad accelerator pump. Have someone go through the carb. Or your carb has lost its fuel. In either case - have a knowledgable person rebuild the carbs.

Re: Switching from mechanical fuel pump to electric??
 

I had gen 6 502 in my 357 kamma boat which had electric pumps that i had nothing but a head aches and problems with,at wide open throttle,the motors would lean out so fast from lack of fuel pressure the valve seats would even fall out from the heat and distroyed the engines(one at a time,rebuild one,the other would blow)could never get it right with hundreds of dollars spent on pumps alone!As far as running 2 inline,tryed that also,didnt work,caused more of a restriction,when one pump would fail,the other had to now pull or push fuel threw a blockage which created a lack of fuel to the carbs and blew motors!Best thing to do is stay with what the motor is designed to use and fix the carbs other wise it could be trouble!Stay with OEM, GOOD LUCK! Try this,put a vacum guage on the motors while cranking and idleing,if the vacum isnt that great your problem could be the motors arent pulling enough fuel air mixture to create a good explosion until the motor is almost flood with fuel!Do they smell rich when they fire and run rich until they warm up?IF week vacum shows on guage,do a leakdown test next!! GOOD LUCK AGAIN!!

Re: Switching from mechanical fuel pump to electric??
 

Thanks everyone! Great insights!

Engines don't seem to be loading up with too much fuel at any time. After reading all this, I'm going to hold on the electric fuel pumps and go over the tips of checking my current carbs and start getting an education on how they work and if they are working correctly. Then resolve any issues I might have there and evaluate the situation again.

Re: Switching from mechanical fuel pump to electric??
 

what is the cost of a new carb, like the demon mentioned? Looking at the rebuild kits, they are about 100-130 bucks. If I put the extra money out for a new carb, would I be gaining anything over the stock carb? I have to get out to the boat and see what kind of carb I have, I'm assuming it's the weber, but don't know for sure.

How do I check to see if the electric chokes are working? If I turn the key just one click, should I see the carb being choked at that time or do I have to watch the carb at the time the motor starts to crank?

Re: Switching from mechanical fuel pump to electric??
 

Sea Demons are $500+ each on Ebay. A guy in WI sells them by the hundreds. The price of your Rebuild Kits seem high. Take the tag off the carb and cross ref at a auto store.
Get a good marine book. If this is happening on both carbs, I think you have other issues. I also had a prob like this with stock carb years ago. I always shot starter fluid down the carb if it sat more than a week. I also do not like the engine turning over for minutes before it roars to life :D

Re: Switching from mechanical fuel pump to electric??
 

I'm telling you I've been there done that and changed everything. "IT'S THE CARBS!" They lose their prime after sitting for a week. Starts okay the next day but, crank the heck out of it after sitting for a week. Sound familiar? I tried rebuilding them but, that didn't help. (BTW Napa has a rebuild kit for much less). Tried adjusting the choke but, that's not causing the problem. I've heard of trying some epoxy in the float bowl walls but decided not to screw with it anymore. BTW; I changed everything from the gas tank to adding MSD ignition before I finally got the problem fixed. I BOUGHT NEW CARBS. A 750cfm Holley or Demon will fix it!

You can PM me if you have any questions.

Bob

Re: Switching from mechanical fuel pump to electric??
 

What motor did you put that 750cfm on? Not sure what size I would need for my 454mags?? What did the holley cost you?

Re: Switching from mechanical fuel pump to electric??
 

I bought some used 800 cfm's from stock hp 500's from a guy on OSO. I re-jetted them for my 502 mags. I think the 750 is what you would need. Just call Bary Grant or Holley and they will be able to tell you exactly what you need and prices. You are probably looking at 350. to 500. each, depending on which model you end up with.

If I remember right you will need to change the mounting pattern on the carb spacer. Don't worry the stud mounts are already drilled out for ya.

Bob