thomas1976

After installing a new stock TPI fuel pump I set FP to 21psi, the fuel pressure drops under load. What can cause this.

Any help is appreciated.

Dewey316

Either the new pump isn't up to snuff, or if you have a slight leak on the rubber connector to the pump, then it can loose pressure also. Was it a brand new pump, or used one?

thomas1976

Pump is brand new ACD#EP241 from TPI parts.
I was certain that TPI pumps were made for 40+psi?

Im going to check for leaks, lower psi and see what happens.

I also hear the pump, is that normal? I never heard the TBI pump.

Dewey316

hmm, is it dropping pressure just at WOT, and high RPM, or when is it dropping pressure, and how much is it dropping?

Hearing it is normal, I have heard every pump I have had in my car.

thomas1976

Id did the first cheks in P by opening the trottle quickly and it dropped 0.5-1psi

Today with 18psi the needle did just move a little. I endet up setting to 16psi and fixed the gauge to the wiper wile dataloging and it never moved even by WOT.

I used a Actron gauge of ebay and I have now some doubts about its readings, although seems a little exagerated if it would be 22 psi off wenn indicating 21psi. Im going to werify with another gauge.

BronYrAur

iTrader: (1)

What spring are you using? If going as high as 21psi stacked the coils that would explain the fluctuation, and would be a nice explanation for you because then it wouldn't point to your pump being too weak.

thomas1976

It is shorter but stiffer as stock one.

It came with xtremefi's stock modified AFPR and I dont know what psi range since his statements are mostli bs.

The lowest possible is 13 psi an the highest in the modified FPR 21psi.

Good point Bron! I hope so much its the gauge or the spring.

Were can I finde a spring that isent maxed out at 20psi?

Darkshot

iTrader: (4)

When I went from a TBI to a TPI pump it was significantly louder. Sounds like the pump you can hear coming from newer GM trucks and SUVs.

Have you replaced the fuel filter lately?

DM91RS

My Walbro 190 was noticeably louder. I wonder how many TBI's drop pressure since there is not a cheap way to monitor it while actually under load.

Except for what you've done.

Dewey316

Mine never actualy dropped pressure, the poor pump just gave up the ghost. )

thomas1976

Was done 1 1/2 years ago. I have it on the next to do list.

Ronny

iTrader: (1)

Top down solutions sells a TBI spring one step higher than stock.

DM91RS

What pressure is that??????

Ronny

iTrader: (1)

My guess is 12 lbs to 20 lbs? My Aeromotive spring is like 10 lbs to 20 lbs. I have it on 19 lbs today. Aeromotive also offers a different 20-40 lb spring with reg.

DM91RS

I need one around 24 or so......but just the spring for the stock regulator.

Ronny

iTrader: (1)

in GM high pressure TBI Truck(1995-1996) they run 26-32 lbs I hear so that spring may be 22 lbs to 40 lbs. I sold a GM regulator and spring(orange color) to Liquid 8 that came with my 1995 TBI unit. You could tell it was obviously stiffer.

DM91RS

Do you know what PN it was?

Ronny

iTrader: (1)

no sorry do not. maybe rock auto can determine if available outside of entire reg purchase.

DM91RS

Thanks........DM

Dewey316

DM, I am running a TDS spring, and have mine set at 24psi right now, it does it with no issues.

I had "heard" that TDS has changed their spring since I got mine. I used to have a spare spring around here somewhere, I have no idea where it is at though, since I moved last year, let me look around and see if I can't find it for you.

Ronny

iTrader: (1)

Be carefull of "coil bind". Bad things happen.

DM91RS

Thanks,

I would love to get my FP up to 24. Downside is retuning for the new FP. Oh well, ya gotta do what ya gotta do............

thomas1976

Thanks to eweryone.

It was extremfi's wrongly rated AFPR sring that wasent stiff anough to hold over 18psi.

Im running 21psi FP since a wile now with AFPR and Top Down Solutions 20psi VAFPR sring is working excellently.