Re: can a mech fuel pump with an electric pump?
[Re: AK_JH27]
#702423
05/19/10 03:23 PM
05/19/10 03:23 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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On a BB you can't forget the accentric. It is part of the cam shaft.
Small block there is no push rod.
Yes it can be done. I don't like it because if the electric pump blows the diaphram in the mechanical it will fill your crankcase with raw gas and you won't even know it till it is too late..
Clean it, if it's Dirty. Oil it, if it Squeaks.
But: Don't fix it, if it Works!
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Re: can a mech fuel pump with an electric pump?
[Re: AK_JH27]
#702428
05/20/10 09:45 AM
05/20/10 09:45 AM
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Joined: Jan 2003
Posts: 6,840
The Swamp
Sixpak
master
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master
Joined: Jan 2003
Posts: 6,840
The Swamp
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Quote:
thanks, I did the above and still no contact, maybe the push rod has been mushroomed on the ends?? what is the length of the rod?
Worn fuel pump push rod is a pretty common problem - just get a new MP one.
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Re: can a mech fuel pump with an electric pump?
[Re: AK_JH27]
#702431
05/20/10 11:17 AM
05/20/10 11:17 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
looks like i screwed up, my fuel pump push rod doesnt contact the fuel pump arm on my 440. It appears that i forgot the eccentric on the cam while i rebuilt the motor.
will this work for a while till I can tear back into it?
PS i didn't even know you could get a cam w/o the eccentric? Isn't it part of the grind?
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Re: can a mech fuel pump with an electric pump?
[Re: Hoof Hearted]
#702432
05/20/10 12:23 PM
05/20/10 12:23 PM
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Joined: Aug 2005
Posts: 403
30 miles west of EuroDisney
fbernard
mopar
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mopar
Joined: Aug 2005
Posts: 403
30 miles west of EuroDisney
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Quote:
I had a Mechanical Hi-Vol pump diaphram fail years ago on my 383 and it simply leaked out of the vent in the housing, not a drop of gasoline got into my block. 
When using a mechanical pump and it fails, the diaphragm loses part or all of its ability to suck in fuel. Thus it can't flood the engine (neither can it bring fuel to the carb which is usually how the driver finds out...)
If the same thing happens, with an electric pump upstream, there's nothing to stop it from filling the mechanical pump body full of fuel. The only way out of the mechanical pump is up through the housing and into the block. Only a piston-type mechanical pump with o-rings would prevent it (and who would use one of those AND an electric pump?)
The only fool-proof way of doing this would be to have a check-valve dowstream of the mech. pump, and plumb in the fuel line from the electric pump after that (with a check valve in that line too so no pump can push through the other).
Or install the electric pump downstream of the mech. pump. But since elec. pumps are usually lousy suckers (they're good ad pushing fuel, which is why they're usually right after the tank or in-tank for cooling), that's not recommended.
Now, if people are lucky and the diaphragm never ruptures, that's OK.
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Re: can a mech fuel pump with an electric pump?
[Re: Hoof Hearted]
#702433
05/20/10 12:42 PM
05/20/10 12:42 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Quote:
On a BB you can't forget the accentric. It is part of the cam shaft.
Small block there is no push rod.
Yes it can be done. I don't like it because if the electric pump blows the diaphram in the mechanical it will fill your crankcase with raw gas and you won't even know it till it is too late..
Is this from experience? 
I had a Mechanical Hi-Vol pump diaphram fail years ago on my 383 and it simply leaked out of the vent in the housing, not a drop of gasoline got into my block.
This is true IF you don't have electric pushing fuel into the mechanical pump and are running the mechanical pump alone. If you have an electric pushing fuel into that mechanical with a broke diaphram it will fill the crankcase.
Also see post by fbernard just above this.
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Re: can a mech fuel pump with an electric pump?
[Re: ireland383]
#702436
05/20/10 01:43 PM
05/20/10 01:43 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
That should still pump enough fuel at that length. Do you have a rubber hose some where in your fuel line with a hole or split? Secondly it could be the pump itself. Good luck!
I chased a similar problem for 2 weeks, replaced the pump, filter. pump rod and gave up. I checked all the hoses, but not good enough I guess, when I tossed on an electric pump I had it found the pin hole in the sender to fuel line hose and blew it wide open. It doesn't take much for the pump to quit sucking fuel and suck only air.
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