[Supras] Fuel pump system priming and pump resistor

[Dan Gyoba]

On 5 Sep 2007 at 5:26, tom wrote:

> Bernie, I left the resistor in place.  No problems.  I did have to
> replace the regulator soon after the swap.  I installed the one from
> the NA and have been running it for two years.   Tom 87NA-T Lexus,
> Lucas 550's, Walbro. 

I've been paying a bit more attention to this lately, since I'll be installing a Walbro as soon as 
I get the time to drop the tank, and before I start upping my boost levels.

The information that I've gathered so far is that the regulator should be replaced.  The 
restriction in the "J" tube should be drilled out to deal with the potentially higher flow.

Many people like to bypass the FP resistor entirely, (Usually just jumpering the relay works for 
this.)  I've seen many dyno graphs at elevated boost levels where the FP resistor does not kick in 
soon enough, and the result is that the engine goes slightly lean, then suddenly kicks into pig 
rich.  This problem seems to be exabberated when using piggyback fuel tuning, since it doesn't 
catch right when the FP triggers.  I don't like lean conditions, nor do I really like the rich 
spike, so I'll most likely take care of this at about the same time as I install the fuel pump.

I would definitely leave the resistor in circuit until the restrictions in the fuel flow are 
removed.  I am also budgeting for an aftermarket fuel pressure regulator for when I do all this.

Dan Gyoba
'89 NA 452,533 kms, Turbo swap COMPLETE
http://www.abstractconsulting.com/~dan