Electric/electronics dudes..

[NeonGTI]

I have installed an aftermarket inline fuel pump as a supplimental pump for my crappy old diesel truck. The pump is a 255 lph and the truck barely requires that amount in a year.

Now when I turn the pump on and it comes up to pressure I find myself with a diesel bukakke - the union at the primary fuel filter can't handle the pressure and shoots everywhere.

Can I vary the voltage going in to the pump to reduce the flow without burning the motor out? Is there a rule of thumb for the ranges in which you can operate an electric motor?

I'm, obviously, pretty noob about this stuff, so any insight would be helpful.

Thanks!

[Benjamin]

Re: Electric/electronics dudes..

What is the PSI rating on the pump? I have used a small pump 5-9 PSI before with a veggy conversion on a jetta and the thing worked great. Never blew a line, although I used screw hose clamps for the whole system. That pump can be found at Princess Auto for $80 and cheaper when on sale.

Benjamin

[NeonGTI]

Re: Electric/electronics dudes..

What is the PSI rating on the pump? I have used a small pump 5-9 PSI before with a veggy conversion on a jetta and the thing worked great. Never blew a line, although I used screw hose clamps for the whole system. That pump can be found at Princess Auto for $80 and cheaper when on sale.

Benjamin

Well the numbers I have for this are 255 LPH @ 50 psi and 290 LPH @ 0 psi. That 50 psi business is where the problem is coming in.

The all-knowing google has plenty of folks who show significant increases in flow with additional voltage (and minimal nasty side-effects) but no one has mentioned dropping the voltage, or putting a variable knob-thingy on.

I suppose another option would be to change the fuel filter out for one that wasn't plastic and had something more stout that a cheap 1/2 inch ring clamp.

As an aside, I am implementing this because, for whatever reason, my little diesel does NOT like the ULSD. Under even moderate throttle you can see the fuel level in the filter drop until it drains dry and introduces air bubbles in to the injection pump. If I let off the throttle before the filter goes dry it will refill nicely, but once the bubbles are there the suction on the fuel line is gone and there is no more feed until I purge the air from the injection pump, hence the secondary pump to maintain the flow.

Oh and ascending hills (like parking lot on-ramps) doesn't end well.

[Benjamin]

Re: Electric/electronics dudes..

ULSD is less lubricating, so would an additive maybe fix the problem? I don't know about lifespans in relationship to pump voltages, but if the Diesel pump on the engine is not having the seals lubricated properly then suction will not happen, hence the lack of fuel. Putting a pump on might solve the problem for awhile, but in the end is it not just hiding a bigger problem? $10 bottle from Lubecorp of super diesel which can do three tanks should tell you if my theory is right. If not, you are only out $10, and little to no labour, easy test I figure.

Benjamin

[Stonewall]

Re: Electric/electronics dudes..

Depends on how much you want to lower the voltage. If you lower is too much the motor could stall out and burn out the brushes. Really it depends on the pump and what you are using to change the voltage. Either way I think it would be easier to get a different pump.

[Boy Racer]

Re: Electric/electronics dudes..

A simple inline power resistor may (if you are really luck) work but the current requirement of an electric motor depends a lot on the speed/ load of the motor so the voltage it sees after the resistor varies too. You could try it out with some low power resistors to see if it works, they may burn up but if you are after proof of concept the you could get an appropriate power resistor.

[NeonGTI]

Re: Electric/electronics dudes..

ULSD is less lubricating, so would an additive maybe fix the problem? I don't know about lifespans in relationship to pump voltages, but if the Diesel pump on the engine is not having the seals lubricated properly then suction will not happen, hence the lack of fuel. Putting a pump on might solve the problem for awhile, but in the end is it not just hiding a bigger problem? $10 bottle from Lubecorp of super diesel which can do three tanks should tell you if my theory is right. If not, you are only out $10, and little to no labour, easy test I figure.

Benjamin

I completely agree that this merely masks the underlying problem, however this is a 1984 nissan sd25 diesel with an unknown number of KM on it and has served as more of a science project than anything else. Also, getting a replacement injection pump for it is next to impossible unless I want to purchase a brand new one (the engine is still in production and in used in forklifts) for a smidge over a grand US. Eww.

That being said, I'll look for the goo when I go shopping for something to toughen up the connection. Blend those things with a voltage drop to 8-9 volts and I could stretch another year out of it.

I'm also going to look for a step down restrictor coming out of the pump. Unless, I can find a pump for similar price.