Custom fuel system help

[Boosted]

Here is the basics. 1992 Typhoon. Fuel Pump died 3 weeks into ownership.
Lines were totally rusted and trashed (Chicago truck) So I bought a new tank, Comp Engineering sump kit, Aluminum lines with Russel fittings. Inline MSD pump and AN fittings filter. I have the pump behind the license plate area. The pump is mid level of the tank where as the outlets of the sump are at the bottom of the tank. I have killed 2 of these MSD pumps (warranty them through work).
I am considering redoing things a little, by going to all braided hose from front to back, and mounting fuel pump where stock fuel filter is (mid truck inside frame). My thoughts are to run a holley blue or red pump to feed the electric pump. I thought I read somewhere that electric pumps do not like pulling the fuel to themselves. They push better than they pull (get your minds out of the gutter :lol: )
Can I run a Holley pump for carbureted applications as the pusher pump, and have it feed the electric pump? Would it flow enough? I realize the Holley stuff is rated PSI no where near an electric, but wouldn't it help the electric by providing a supply to the electric pump and letting the electric push it up to the PSI that I need? If this set up works I will probably go to an Aeromotive electric instead of the cheapie MSD, but I dont want to spend the big bucks on Aeromotive until the system is scienced out.

I will post pics of this as soon as I get home. At work right now.

 

[leroy]

Hi Zach,

The MSD pump is made for inline applications, so should work okay.

Cavitating the pump would be hard on it. That happens when you are trying to pump more fuel than is available at the suction side. A clogged filter or suction lines that are too small could be the cause. In-tank pumps have a sock to keep out big stuff, but the main filter is on the pressure side of the pump. I can't remember how yours is set up exactly.

It may be worthwhile to check the wiring to the pump also. Inspect all the connections. You might be able to hook up a voltmeter and watch it in the cab.

HTH,
Jim

 

[Boosted]

Hi Zach,

The MSD pump is made for inline applications, so should work okay.

Cavitating the pump would be hard on it. That happens when you are trying to pump more fuel than is available at the suction side. A clogged filter or suction lines that are too small could be the cause. In-tank pumps have a sock to keep out big stuff, but the main filter is on the pressure side of the pump. I can't remember how yours is set up exactly.

It may be worthwhile to check the wiring to the pump also. Inspect all the connections. You might be able to hook up a voltmeter and watch it in the cab.

HTH,
Jim

My filter is after pump, mounted around where stock location filter goes.
I understand the basics of Cavitation, but not sure I totally understand what you are saying here. My return comes in the sender at top, so it spraying the fuel on top of the existing fuel level, and the pump is drawing it from the bottom of the tank. My concern is the pump itself is located higher than the sump outlets, so its having to suck the fuel up to the pump....hence my thought of a carbed pump sucking it out of tank since thats what they are designed to do and have it feed the electric pump, say further up the frame. ?? :-?

 

[leroy]

My concern is the pump itself is located higher than the sump outlets, so its having to suck the fuel up to the pump....hence my thought of a carbed pump sucking it out of tank since thats what they are designed to do and have it feed the electric pump, say further up the frame. ?? :-?

Yes, you have some pressure loss on the suction side due to lift. I don't know if that's enough to cause problems. You could just move the MSD pump further up the frame (to a lower spot).

If the pump is lower than the fuel level you would gain a little pressure on the suction side because of head pressure (even if the suction line goes up and back down to the pump). But, by moving the pump farther away from the tank, you will lose some pressure due to friction loss. Friction loss can be minimized by using larger diameter lines.

How is the pump failing? Is the motor burning up or the pump? I would expect cavitation to damage the pump first. I think electrical problems or debris in the pump would be more likely to cause motor failure.

Jim

 

['JustDreamin']

Hey Guys...

I'm one of those newbies, so take my thoughts with about a 1/2 lb of salt.

First thing I'd do is to check with MSD customer service. If you've lost 2 pumps already, then 1 of 2 things is happening. Either your setup is killing them, or they're having some serious quality type problems. Best to see if you can figure out which is which first.

If MSD has problems, then hopefully they've figured out what was wrong (with that batch of pumps) and have corrected it.

If you've got the problem, here's the things I'd try:

1.) Lower the pump in its current location (if possible). That should give the pump the best chance at fuel with minimum flow losses.

2.) Make sure your lines are big enough (what did you put in, and what does MSD recommend?) Bigger is almost always better.

3.) Make sure that your filter is big enough and not plugged. I assume that you bought it based on size, but y'know what assuming does.


Typically you get less restriction to flow with hardline than with hose (for the same given size). Walls are just a little smoother. Bends in the line do increase the flow restriction, but fittings really trip it up (especially tight 90 degree elbows and such). Also, check for kinks in your hardline (hopefully there aren't any).

The electric inline pumps do push better than the suck. The old mechanical styles (mounted to the engine) are diaphram pumps, and they "suck" great. Thats why the factory flipped the fuel system around and put the pump in the tank when they went to electric pumps.

'Dreamin'

 

[Boosted]

How is pump failing:
vehicle starts to thrash about, lunging and surging, and missing. Happened when Morgan and I left Nats for a BBQ. We pulled to side, and let it cool....no help. I broke open the filter and banged out the little crap that was in there....no help. It finally calmed enough to barely get me to the location.
Next day I brought over a new pump, installed it, and the truck pulled like never before. No other changes were made.

Electrical or Debris......Possible, but filter has been cleaned several times, (Russel inline with AN fittings. Filter can be separated and screeen filtering media cleaned for those other than Jim)
Connections are suspect, but I never have to "wiggle any wires" to make it work, but there is exposed connections that could corrode. I will make a point to remove totally this weekend and do the connections up right.....'

I used Moroso alum line with Russel compression fittings, Brass compression made to work with the alum line. Bends are smooth kink free. But because of sump, the pump is at the beltline of the tank, a good 6 inches higher than the sump.