mech to elec fuel pump - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> General Rodding Tech
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-25-2010, 02:43 PM
done learning, done living
 
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 29
Posts: 1,712
Wiki Edits: 0

Thanks: 159
Thanked 92 Times in 83 Posts
mech to elec fuel pump

I have a 1985 OMC 3.0 Liter in my boat. I have had fuel issues with it for the last 3 years. The engine was rebuilt when I bought the boat 3 yrs. ago. The previous owner told me that the boat had problems and he was just tired of it so he bought a different boat. I purchased the boat for a really good price and rebuilt the engine. After burning a hole in one of the pistons the first year I had it I haven't really messed with it. I am back at it now. I figure the piston got roached due to running lean. So I replaced the piston and paid a little more attention to the engine while on the water. The engine was still running lean so I replaced the fuel pump. The engine still runs lean. I replaced all of the fuel lines and had the carb rebuilt. The engine still ran lean and the last time it was on the water I had to be towed in (broke down on the water f'n sucks ***). I pulled the fuel line off the carb and rolled the engine over, and fuel drizzled out of the line, it was a constant drizzle. I changed the fuel pump back to the original one that was on it and it is doing the same thing. Is there a chance when the engine was rebuilt the lobe on the cam isn't large enough to properly pump the pump? My main question is I would like to set up an electric fuel pump but need to do it correctly and make it Marine safe. I would like it to be set up on an oil pressure switch but also am wondering if something else needs to be installed while going from mech to elec pumps. Is there a pressure switch that would shut the pump off? If someone could give me some advice on this or at least point me in the right direction it would be nice.

Sorry for the long post

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-25-2010, 03:23 PM
SS66chevelle's Avatar
HR VIOLATION
 
Last photo:
Join Date: Nov 2003
Location: Rockford IL
Posts: 159
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I just installed an electric pump on my gen 6 502 and did a ton of research. This is what I learned:

1. install a pressure regulator with a gague on it as close to the carb as possible. If you are running a carburetor you only need 5 or 6 PSI at the carb
2. use a gerotor style pump like the holley HLY-12-125. do not use a vane style pump because most of the vane style pumps (like the holley blue, red, black etc) are not made for continuous duty and they crap out all the time
4. wire the pump using a relay (very important!!)
5. a dead head configuration is fine for a carb setup (no fuel return line needed)

Hope this helps get you started
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-25-2010, 04:47 PM
302 Z28's Avatar  
Last photo:
Join Date: May 2003
Location: North Texas
Posts: 10,839
Wiki Edits: 0

Thanks: 1
Thanked 86 Times in 73 Posts
Very important, make sure whatever fuel pump you buy it is rated for marine use.

Vince
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-25-2010, 07:09 PM
DOCTOR DC's Avatar
NUCKINFUTS MOTORSPORTS
 
Join Date: Apr 2010
Location: PACIFICNORTHWEST
Posts: 111
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
all fuel hoses must be double clamped and fuel filter must be installed between pump and carb. brass ball valve at filter inlet helps when changing filter. you have changed the filter right?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-25-2010, 11:11 PM
done learning, done living
 
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 29
Posts: 1,712
Wiki Edits: 0

Thanks: 159
Thanked 92 Times in 83 Posts
ok, here is the scoop.

I went to the auto parts this past afternoon, well yesterday afternoon i guess but anyways i bought a carter electric fuel pump. It is a solenoid style pump part number P74019.

From the tank I have a fuel filter then the pump then another filter before the regulator then to the carb. Is this correct? Do I need the second filter? There is no filter in the carb inlet. I plan on wiring the pump with a 10 amp inline fuse also wired up to an oil pressure switch that carter recommends. The pump came with a wiring diagram so I am set on the wiring. I am just curious if this is correct. The pump is rated from like 5.5 to 9 psi at 30 gph or something like that. Will the pump shut itself off when pressure is built? Will it turn on and off constantly when at an idle or low throttle if pressure is met by the regulator? The engine is a 1985 OMC 3.0 Liter, If I understand correctly this is the same engine as the 2.5 iron duke. I am curious if anyone would know what to set my fuel pressure at or at least a starting point? Or even a minimum and a maximum then I can play with it from there?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-26-2010, 01:13 AM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: Portland,Or
Posts: 840
Wiki Edits: 0

Thanks: 0
Thanked 43 Times in 37 Posts
You did check all the hoses from the tank to the pump, before you condemned the pump, didn't you? Now might be a good time to make sure you have good hose, that can withstand having a little alcohol mixed with the gas.

The fuel pressure sounds high to me. Remember, on a boat, if you put excess gas in the carb, and is spills. you are adding gas fumes that stay in the bilge, waiting for a spark, from the starter to explode.

Before radically changing the fuel system on a boat, make sure you are doing the right thing. Cars rarely blow up from a little gas spill. Boats do, way too often.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-26-2010, 06:54 AM
Registered User
 
Join Date: Feb 2007
Location: MN
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Are you vapor locking? The fuel lines aren't getting too close to heat sources?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-26-2010, 05:20 PM
done learning, done living
 
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 29
Posts: 1,712
Wiki Edits: 0

Thanks: 159
Thanked 92 Times in 83 Posts
when I put the new mechanical pump on I changed all of the lines going from the tank to the carb, I even tried running out of an outboard boat tank. The fuel pumps pump but it is just a constant basically drizzle from the hose. I am curious if the lobe on the cam is to small and just doesn't pump the pump correctly.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-26-2010, 05:40 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,036
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by crussell85
when I put the new mechanical pump on I changed all of the lines going from the tank to the carb, I even tried running out of an outboard boat tank. The fuel pumps pump but it is just a constant basically drizzle from the hose. I am curious if the lobe on the cam is to small and just doesn't pump the pump correctly.
The pump cam can wear, as can the push rod if the engine has one, unusual because there isn't nearly the load that a cam lobe for a valve sees, but I suppose it's a possibility.

I'd check the push rod length to a new one as a start.

As for the electric pump, you want it lower than the fuel tank if possible or as near to this as practical.

A pump like you have is tolerant of dirt and etc., but running a pre-pump filter wouldn't hurt.

The regulator should also be near the carb, and set to about 5psi.

That said, I do not pretend to know what the CG regs are on such things- I'd have to advise that you bone up on the regs before doing anything.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-26-2010, 06:21 PM
Registered User
 
Join Date: Feb 2007
Location: MN
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I just put on an electric fuel pump, (bosch), because my fuel pump pushrod and cam lobe wore off. I put a hacksaw blade in front of the pushrod and held it up and had the wife hit the key. almost no movement. So, I put the inline pump on after a filter, and a clear filter ahead of the carb. Well, I was only getting a drizzle, also. I ran hose from the frame to the carb. Well, the hose doesn't fit as nice as the steel line did by the front of the engine. The hose was touching the water pump. I moved the line totally away from the engine, and hanging off tghe air filter, so far. Looks stupid, but it appears to be the fix. Oh well.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-26-2010, 06:49 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,036
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by denunger
I just put on an electric fuel pump, (bosch), because my fuel pump pushrod and cam lobe wore off.
With the oil additives being changed, we might be hearing more of this in the years to come. Good job figuring it out, anyways.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-27-2010, 11:44 AM
done learning, done living
 
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 29
Posts: 1,712
Wiki Edits: 0

Thanks: 159
Thanked 92 Times in 83 Posts
i have no fuel pump pushrod and the cam is only like 4 yrs old. if that. I mounted the fuel pump closer to the carb than the tank, there is maybe a total of 4 feet of line between my tank and carb. I mount the pump up on the engine because I would like to keep the pump from being submerged in water if I can. Is it really bad to have it closer to the carb than the tank running such a short amount of line. I guess my thought was that these fuel pumps are designed to push fuel like 15 or so ft. to the front of a vehicle.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-27-2010, 04:01 PM
Registered User
 
Join Date: Feb 2007
Location: MN
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I was working on an old '84 suburban. The fuel lines were spliced about halfway to the front. I mounted it there, but I also knew that when I pushed fuel up there with a little air pressure, it would have siphoned there all day; so I was tentatively ok with that.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 07-03-2010, 04:18 PM
done learning, done living
 
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 29
Posts: 1,712
Wiki Edits: 0

Thanks: 159
Thanked 92 Times in 83 Posts
ok, I had the boat in the water today with the electric fuel pump installed. The fuel pump is mounted close to the tank with about 16 inches of line running from the tank to the pump. The engine runs with the electric pump it would not run at all with the mechanical pump. When I got it out on the water I was running through the no wake zone and it was running good. When I got out of the no wake zone I opened it up to wot and she fell on her face after maybe 50 yds if that far. I flipped the engine cover back and a buddy was driving the boat. At wot the fuel pressure drops down to like 2.5 pounds. Should it maintain a 5-7 psi flow? Do I need a bigger fuel pump? After I would throttle the boat down for a minute or so she would take off again at wot for about 50 yds again. I can "troll" all day long I can do probably 15 mph all day long but I cant open it up because it runs out of gas
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 07-03-2010, 06:38 PM
Registered User
 
Join Date: Feb 2007
Location: MN
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
That's what happened to me, basically. If I hit the highway and accelerated, I fell flat. I would always start up again. Could barely accelerate. My hose just touched the engine and it was enough to vaporize the gas. My fuel is as far away from anything on the engine as I could make it: It seems to have straightened out. Or do you have some crud in your gas tank?
Reply With Quote Quick reply to this message

Recent General Rodding Tech posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Locating Methods For Air Leaks In Mechanical Fuel Pump Fuel Lines J.J. LASALLE General Rodding Tech 6 06-29-2009 02:04 AM
sbc mech fuel pump install... Prof. T. Soggmeyer Engine 2 06-15-2009 09:38 PM
elec fuel pump wiring yragat Electrical 28 05-21-2008 06:52 AM
changed fuel pump from mech to elec - HELP! junkyard junkie Engine 16 09-19-2007 08:30 PM
93 dodge shadow fuel pump repair junkie Electrical 2 10-02-2003 09:05 AM


All times are GMT -6. The time now is 08:22 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.