85 fuel pump in a 84
Thread Starter
Racer
Joined: Sep 2008
Posts: 273
Likes: 0
From: Tallahassee Florida
85 fuel pump in a 84
My fuel pump just went out in the 84 Crossfire.. Heard some people talking about putting a 85 pump in and getting a pressure regulator.. My question is what regulator do I need to make this setup work? The 85 regulator is located on the fuel rail the 84 isn't. Also the 84 is only rated at 13psi the 85 is 13-30 or so psi.. Any advise or does anyone have a regulator that will work?
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
My fuel pump just went out in the 84 Crossfire.. Heard some people talking about putting a 85 pump in and getting a pressure regulator.. My question is what regulator do I need to make this setup work? The 85 regulator is located on the fuel rail the 84 isn't. Also the 84 is only rated at 13psi the 85 is 13-30 or so psi.. Any advise or does anyone have a regulator that will work?
Pro
Joined: Jul 2002
Posts: 703
Likes: 0
From: Milwaukee Wi
There is disagreement on this forum regrding the value of the higher pressure TPI FP. I added it to my stock 84 and could not feel any difference SOP. I replaced a good 84 pump with 70K miles on it with the 85. That allowed me to adequately fuel my future mods planned.
the stock FP reg is mantained. Many will add a FP gauge and set the FP to 13 lbs by modifying the reg to be adjustable. I suspect the stock reg with factory setting may show 12 lbs with either new pump.
I have since replaced the stock reg with an Aeromotive unit.
the stock FP reg is mantained. Many will add a FP gauge and set the FP to 13 lbs by modifying the reg to be adjustable. I suspect the stock reg with factory setting may show 12 lbs with either new pump.
I have since replaced the stock reg with an Aeromotive unit.
Racer
Joined: Jun 2005
Posts: 275
Likes: 0
From: Pembroke NH
Thread Starter
Racer
Joined: Sep 2008
Posts: 273
Likes: 0
From: Tallahassee Florida
Yea but the pumps have a good bit of difference in psi... my mechanic and i looked on his computer and it said max fuel pressure on a 84 pump is 13 psi.. The 85 said some where from 13 and 25 or 30 max psi.. So in that case wouldn't it make a difference if I had it running at 16 maybe 17 psi? and the regulator on a 84 isnt adjustable..
Racer
Joined: Jun 2005
Posts: 275
Likes: 0
From: Pembroke NH
84 is adjustable, you just need to knock out the plug on the base of the regulator. An 85 pump will definately not hurt an 84. The regulator will knock down the pressure to stock settings if you do nothing and if you chose to make it adjustable you can go up to 14-15 lbs safely.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
84 is adjustable, you just need to knock out the plug on the base of the regulator. An 85 pump will definately not hurt an 84. The regulator will knock down the pressure to stock settings if you do nothing and if you chose to make it adjustable you can go up to 14-15 lbs safely.
exactly, remember you already have a regulator that will adjust that pressure down to feed your tb's. So the 85 pump won't hurt it at all. Many of us have put in the 85 pump, myself included. My pressure runs at 13 psi with the newer style pump.
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Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Let's clarify a couple of things.
1. Pumps create FLOW...not pressure.
2. Restrictions to flow create pressure.
Think of it this way....if you ran the pressure hose from an 85 pump into a bucket, it would flow at near zero pressure. The restriction the pressure regulator gives is what causes pressure to build.
That said, the regulator on your rear throttle body will limit the pressure to 13 psi max, even with the TPI pump....The 85-91 pump doesn't create enough flow to cause it to go over that.
Now...you will gain ZERO performance on a stock engine over a properly working 84 pump by switching to a later pump. The 85-91 pump is, however, more readily available, and not much more money, if any. It also allows for future mods. When my original pump on my 84 went bad, I went with a 85 pump for that reason.
Your call.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
If in the future your going to do more major upgrades then it may be time for a new regulator. With my mods in my sig I'm only running at 13psi.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
