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Discussion Starter #1
Hi guys I dont post much here but do a lot of reading and trying to learn. I picked up a 78 Hallett last summer with a 460, tunnel ram, and dual holley 600's. It runs good but I was wondering why it would need a mechanical fuel pump AND an electric fuel pump. The holley red electric pump is mounted to the back of the transom right after the T for the two tanks and then feeds the mechanical pump. The reason I ask is the holley pump sounds like it is ready to die and I also noticed my fuel pressure at idle is only 4psi and right at 5psi at wide open throttle. I was thinking of just getting a better electric pump and getting rid of the mechanical, or is there some good reason to keep using both.
 

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My guess is the electric pump is a primer pump for the mechanical. Depending on the size of your boat, it can be asking a lot for a mechanical to draw fuel all the way from the side tanks to the motor. As far as eliminating the mechanical, that's your call, but your pressure sounds pretty good and you may have to start over if you eliminate the mechanical with a new electric pump and regulator. My suggestion would be to replace the electric (helper) and leave the mechanical, ie; leave it the way it's working now.
 

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Discussion Starter #3
Ok thats what i was thinking that it was a helper for the mechanical. I agree ill just replace the electric pump and call it good. Thanks for the reply
 

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Quick way to kill a Holley red is asking it to pull fuel out of the tank. They're designed push gravity fed fuel. Shouldn't need both, the mechanical should be sufficient.
 

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I think the electric pump is hindering the manuel pump.The elec pushes where as the manuel will pull the fuel. I would eliminate the electric pos holley red before it leaves you stranded. You cant pull fuel through a electric pump that is locked up.

I run a clay smith pump (Mech) with zero issues in 6 years on a 540 with two 1050 dominators. Plenty of fuel on hand and you can dead head the pump.
 

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Discussion Starter #6
Decisions, decisions, I wouldnt mind getting rid of the electric pump at all. The boat does have problems staring when it is hot. When hot it has long crank times and will pop and try and start during cranking and then eventualy start. I am wondering if the previous owner added the electric pump thinking it would help the hot starting problem, which it didnt. Thats another problem I havent figured out yet. So Clay Smith is the way to go when it comes to Mechanical pumps, any others ??
 

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"BOATLESS"
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Decisions, decisions, I wouldnt mind getting rid of the electric pump at all. The boat does have problems staring when it is hot. When hot it has long crank times and will pop and try and start during cranking and then eventualy start. I am wondering if the previous owner added the electric pump thinking it would help the hot starting problem, which it didnt. Thats another problem I havent figured out yet. So Clay Smith is the way to go when it comes to Mechanical pumps, any others ??
My brother runs this with 710hp @6350rpm on motor.
Holley Ultra HP Billet Mechanical Fuel Pumps 12-454-25 - SummitRacing.com
He runs this for his 2 stage nitrous plate system, one stage at 75hp and the other stage at 200hp, works perfect.
Edelbrock Electric Fuel Pumps 1792 - SummitRacing.com


Me, i run this for my motor,720hp @6500rpm on motor
Edelbrock Electric Fuel Pumps 1792 - SummitRacing.com
I run this for a single stage nitrous plate system 250hp
Mallory Comp Pump Fuel Pumps 4150 - SummitRacing.com

Both boats seam to work great with these set ups, both boats make close to 1k on the nitrous, oh we also run external enrichment tanks with 116 octane fuel in them to be on the safe side

Later

Trevor.

 

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You've gotten all good answers here. I think you're right on figuring out if the electric pump is a
band-aid for another problem. You didn't mention how big a boat you have. If it's a day cruiser and you have a long pull for the fuel to get to the carbs, it may be asking a lot for a mechanical. I've seen several guy's burn up starters trying to pull fuel to a dry carb in big boats. This is where I would maybe add a helper electrical pump to push the fuel to the engine.

As far as I'm concerned, Clay Smith is the way top go for a mechanical. I have one on my blown BBC. I dyno'd it Saturday and the fuel pump was still producing 6psi at 6000rpm.
 

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Discussion Starter #10 (Edited)
the boat is a 19ft Hallett sprint. Tank pick ups are at the transom going to a T and then off to the motor which is maybe a 5 foot run at the most. Motor is nothing special around 450HP. I cant imagine I really need both pumps for this motor. At this point it sounds like I need to verify if the mechanical is actualy working and then a decision to go with electric pump or mechanical pump :bangmyhead:
 

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Oh hell if your only pulling fuel 5', a good mechanical should do that no problem. I'm sure once you figure out why your boat doesn't start hot, you'll only need the one pump.
 

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Discussion Starter #12 (Edited)
Ya i am thinking heat soak because I noticed that after shutting the engine off my fuel pressure rises from 5 to 7 PSI, once it drops down to normal it fires right up. I know the electric vs mechanical pump debate is pretty heated but I think I am leaning toward an aeromotive electric pump (I have a pressure regulator in the system currently)and eliminating the mechanical. Iam still on the fence about it....... tomorrow could be a different decision :)
 

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I run a Weldon electric pump on my high HP boat and a Clay Smith on the cruiser. Both will handle high HP but the Clay Smith is less hassle. Go with the Clay Smith.
 

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Ive been running a CV mechanical pump on my 540 deal for almost 4 years now and I know one thing......It works!
 

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Discussion Starter #17
well decided on the aeromotive pump since all the wiring and plumbing is all ready set up. We will see how it go's, and hey I will have a mechanical for a spare just in case :) Thanks for all the suggestions and help!!
 

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Discussion Starter #18
Well damn i guess i shouldn't have went this route. Ive had nothing but problems with the aeromotive pump. Seems its cavitating, heating up, and hydrolocking, real fun when the engine quits while your cruising!! Is it possible to have too much GPH for the demands of the engine causing cavitation? Ive replaced all the lines from 3/8 to 1/2" new filters, 100 micron filter before the pump and a 40 micron between the pump and carbs. Pump mounted below the tanks. Stumped why this is happening!
 

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I run a 427 with 660's that i run wot for as long as i can. 2 equal length #8 to a 'T" to a $29 airtex with the bypass line plugged from auto zone. It makes 7psi @ 6800 even with 2 gal in each tank. Running electric and mechanical makes no sense. Electric only push,
and they don't push air very well at all. I ran electric with tanks that feed from the top, when the tanks gets low and sucks air fuel pressure takes a dive.
 

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Does anybody have any experience withe the Stewart Race Pumps on boats? Have heard many stories bot good and bad on these. Whats the latest? Have they fixed their issues?
I have been running mine for several yrs now without failure. My twin turbo 555cid BBC runs 25psi of boost with out any problems. Great pump, regs. :))THumbsUp
 
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