fuel pump question

guglielmo6160 · Post by **guglielmo6160** » Tue May 26, 2009 2:08 pm

as a mechanic, I think I already know the answer to this question, but I like asking you guys as you know your boats, better than I ever will, so heres another question

I have two mechanical pumps on my ford 302's my question is , I ran out of gas on my port engine, and it took a long time to re prime the carb bowls,
what do you dudes think of installing a couple of electric pulse type fuel pumps in series , before the mechanical pumps as a sort of priming set up? I mean its easy enough to do, and I can even set it up where I can install a series of bypass valves and hoses that I can use as an emergency run set up in the event of a mechanical pump failure, any thoughts?

jav · Post by **jav** » Tue May 26, 2009 2:48 pm

why not a priming bulb circuit?

Dan Faith · Post by **Dan Faith** » Tue May 26, 2009 3:22 pm

I will work and you can if properly installed use it in the case of a mechanical pump failure. This is the set up on my airplane, a mechanical pump supplies the fuel in normal operation, to stop the engine the lean mixture is pulled and this runs the engine carb or injection system dry. To start press the electrical pump to prime to start, if you run tank dry switch tanks turn on electric pump and start (takes too long for mechanica). If failure on mechanical pump just turn electric pump on full time operation. A lot more critical in the air than on the water costs could be a factor and find an electric pump that is explosion proof for marine operation.

ltbrett · Post by **ltbrett** » Wed May 27, 2009 5:05 pm

I ran with that set up for about a season. My port mechanical pump failed due to cam wear and I put an electrical pump in series before it. I made the repair just prior to taking a party underway, so I left the old pump in place until I got around to removing it. So yes, it will work. But then you must ask yourself why have a mechanical pump in the circuit at all? I wired in cranking relays, so if you crank the engines a couple of times then pause, the electric pumps kick in and prime the carbs. Fires right up, even after being left for a week or two in December.

Brett

guglielmo6160 · Post by **guglielmo6160** » Thu May 28, 2009 6:59 pm

Im going with the electric pumps, I have had bad luck with the mechanical pumps when you run out of fuel, the electric pumps work great and are a snap to change, if they fail, just carry a spare and you can change iti in a matter of minutes

g36 · Post by **g36** » Fri May 29, 2009 8:36 am

i was curious i dont need to do anything with my pumps at the moment but a couple of posts earlier dan faith made a comment about the electric fuel pump being explosion proof, has this been addressed in the pump that you are going to install?. also for future reference whats the make of the fuel pump are you going to install? i havent had trouble with my mechanical pumps so i dont know if i would ever switch but there does seem to be some issues that need some attention if switching

Dan Faith · Post by **Dan Faith** » Fri May 29, 2009 8:58 am

Any electrical equipment in the engine room must be Marine grade. In industry we called them explosion proof (No external spark). This is the same as not using a car fuel pump in a boat.

Here is a link to a couple replacements.
http://www.101part.com/fuel/fuel-pumps/ ... marine.htm

http://marineengineparts.com/shopsite_s ... age81.html

Safari · Post by **Safari** » Fri May 29, 2009 9:08 am

I keep a Carter marine electric pump permanently mounted that I use as an emergency backup (never used) and to pump fuel off at the end of the season. This pump replaced an expensive Holley pump that leaked. My experience is that mechanical pumps are extremely reliable. If you replace them every 10 years, you will probably never experience a failure. One thing to consider is that carbs require low pressure (maybe 4psi); electric pumps can deliver 40psi so you will need a regulator.
Electric fuel pumps will run whenever they are switched on, which can lead to extremely dangerous situations if there is a leak due to mechanical fault or an accident. Mechanical fuel pumps are much safer, due to their lower operating pressures and because they 'turn off' when the engine stops running.

prowlersfish · Post by **prowlersfish** » Fri May 29, 2009 1:16 pm

They make low pressure marine electric pumps .the 40 psi pumps are for FI not carbs

Dan Faith · Post by **Dan Faith** » Fri May 29, 2009 2:42 pm

They also make a safety switch that, should be used, put in with the oil pressure unit that shuts down the electric pump when the engine is not running.

guglielmo6160 · Post by **guglielmo6160** » Fri May 29, 2009 10:15 pm

safari
the pumps your referring to that produce more than 4-5 psi are used for fuel injection, there are numerous pumps that supply the exact pressure that a mechanical pump produces between 4-6 which are commonly used for carbueretor float type set ups
in regards to a fuel pump working only when you turn it on is inaccurate, an electric pump should ONLY be installed with a relay system that will only activate the pump during engine crank and run situations, it would be foolish to install an electric pump that runs with the engine off' and I disagree with a mechanical pump being reliable, I have had nothing but problems with mechanical fuel pumps , and I do this for a living, so I can tell you with confidence that electric fuel pumps are far more reliable than mechanical, in my opinion,. but its all a matter of opinion. I just like the idea of being able to prime my enignes faster when I need to. and the replacement of an electric pump is far quicker than mechanical. and much much easier to diagnois.

and G36 carter makes a marine grade fuel pump which does not spark, but there are also many other plastic body solid state pumps which are safe as well,
remember, do you think an automotive electric fuel pump will spark??
I think not

prowlersfish · Post by **prowlersfish** » Fri May 29, 2009 10:32 pm

http://motors.shop.ebay.com/merchant/ct ... Z1QQ_fromZ

guglielmo6160 · Post by **guglielmo6160** » Fri May 29, 2009 10:42 pm

and this

http://shop.ebay.com/items/_W0QQ_dmptZO ... &_osacat=0

Dan Faith · Post by **Dan Faith** » Sat May 30, 2009 6:47 am

I will disagree with the use of an automotive fuel pump in a marine application, Why do you think they make marine grade fuel pumps? Also a general statement of electric fuel pumps being more reliable is too general a statement. I have had six electric fuel pumps in my corvette installed and gauranteed by a Chevy dealer, never had a problem with a mechanical pump. Also have had local mechanics change over electrical to mechanical pumps due to problems. But I would never make a general statement as to one being better that the other.

prowlersfish · Post by **prowlersfish** » Sat May 30, 2009 7:29 am

Dan Faith wrote:I will disagree with the use of an automotive fuel pump in a marine application, Why do you think they make marine grade fuel pumps? Also a general statement of electric fuel pumps being more reliable is too general a statement. I have had six electric fuel pumps in my corvette installed and gauranteed by a Chevy dealer, never had a problem with a mechanical pump. Also have had local mechanics change over electrical to mechanical pumps due to problems. But I would never make a general statement as to one being better that the other.

I agree you should us marine grade pumps . I made a lot of money off mechanical pumps in their day now I make a lot off electric pumps .what do I think is better ? To me its a toss up they both have pros and cons .