Now that I can watch it, been able to watch my fuel pressure. Mind you this is a stock fuel set up, still have the bowl / filter, stock pump with no extra pump, and added a rail filter as part of my harpoon / hutch mods.

-While cruising about 55-65 mph, reads right at 60-62 psi
-If running about 30-40 and do a hard accel (with DP tuner in 80 econo) pressure drops to just below 60 psi
-From a stop, in 80 econo, on a HARD acceleration it drops to just above 50psi.

Seems like I lose a lot of pressure when I'm really demanding fuel, right ???

 

On stock injectors you can sometimes see a slight drop in pressure, but to see a 10 lbs drop, I would think your pump is a bit weak. My stock pump only dropped about 3 psi on the highest settings, right up until it started dying.

 

Your not hurting anything at those pressures, but it is a bit much. Keep an eye on it but I would not worry.

 

wow, i have never seen mine get that low even when pushing her hard. mine sits right at 70 @ idle and will drop to about 62 under hard acceleration. that is where it always is 60-70, completely stock.

 

wonder if I should either replace the stock pump, or change it out for a better one ...

 

You haven't shimmed your FPR David? That seems like numbers after a shim...

 

negative. i did replace the fuel pump a few years ago. got the best one i could from oh-rye-lees.

 

Nice. Whadya get?? Might have to look for that one when I need to replace mine...

 

yea that seems low, i have the RR kit set to 65 psi and it never moves, maybe 2-3psi max on a hard accel but thats it.

 

Just an update:
my truck runs on WVO and I just went through my first filter, as it was getting too dirty to run my pressure was dropping, check you filter, this may be the problem.

After replacing the filter I had to let my truck idle for about 20min before all the air was out of the system, with air in the system the pressure would not stay constant at all, and would fall below 50 if I gave any throttle at all.

 

I think it's time for a new pump. mine would drop 10-20 psi (depending on FPR shims) at WOT. Installing a new pump made a significant difference in power, back to were it should have been. I put in a walbro 392.

 

and you just replaced the OEM pump with the Walbro ?

 

That's what I did too. The Walbro outflows the stock pump, and only costs about $125. If you have already done the pre-pump mods, then this pump is a straight up bolt on. I can't get it to drop any pressure even on my highest setting, and I'm running close to 70 psi of pressure.

 

as far as pre pump mods, yup it's hutched and harpooned, and I have a rail mounted Baldwin filter and larger fuel lines - have a part # for it ?

 

I think I found it .. Pocket is this the one ?? Arizona TPI :: Fuel Pumps :: Walbro GSL392