Fuel pump
12-10-2015, 12:15 AM
#1
Racer
Thread Starter
Fuel pump
This may have been asked before, can you install a 1985 fuel pump/sending unit assembly on a 1984? What is the main difference between those two?
12-10-2015, 12:21 AM
#2
Team Owner
Pro Mechanic
I'd guess that they're the same, physically fitting wise.
The '85 pump has produces more volume and pressure, though it's physical shape/size is nearly identical to the '84 pump.
The '85 pump has produces more volume and pressure, though it's physical shape/size is nearly identical to the '84 pump.
12-10-2015, 01:27 AM
#3
Racer
Thread Starter
I think I read that they made improvements to the sending unit in 1985 and that is what I am looking for( a more reliable unit ) I am going to give it a try.
12-10-2015, 11:23 AM
#6
Team Owner
Pro Mechanic
That is true, but fortunately, the pressure is managed by the regulator. Pressure is resistance to flow...neither pump puts out any measurable "pressure" when pumping into a bucket (for example). The stock CFI regulator works just fine w/the higher volume MPFI pump...and even more. I ran a Walbro 255 lph pump in my CFI car, factory regulator set to 15 PSI. 
12-10-2015, 02:27 PM
#7
Le Mans Master
Not debating the need for the regulator. OP just has to be aware that there is a major difference. And perhaps be proactive and put in new regulator if he upgrades the pump. The 85 pump will fill your bucket much faster than the 84 pump. 
DAMN sounds like another "bucket list" thread.......
DAMN sounds like another "bucket list" thread.......
12-10-2015, 03:52 PM
#8
Safety Car
12-10-2015, 10:45 PM
#9
Team Owner
Pro Mechanic
12-11-2015, 12:22 AM
#10
Racer
Thread Starter
I already have been looking for the 85 pump assembly, on eBay they show also a what I believe they call a pulsator, now the sending unit assembly does not show a part that looks like what they are selling, where is that part located? The 84 and 85 pump looks the same, is that something that I will need if I use the 85 assembly or is it something not needed? I have not seen that part listed when looking at the 84 units.
12-11-2015, 12:33 AM
#11
Team Owner
Pro Mechanic
The '84 likely does not have that part due to the low operating pressure, and the design of the '84 pump. The "pulsator" is supposed to operate like an accumulator, smoothing out any pulses crated by the pumping action of the 85^ style pump. It is not necessary in your '84, but it won't hurt to have it either.
12-11-2015, 12:42 AM
#12
Racer
Thread Starter
The '84 likely does not have that part due to the low operating pressure, and the design of the '84 pump. The "pulsator" is supposed to operate like an accumulator, smoothing out any pulses crated by the pumping action of the 85^ style pump. It is not necessary in your '84, but it won't hurt to have it either.
12-11-2015, 02:30 AM
#13
Team Owner
Pro Mechanic
It is typically immediately above the pump's outlet.
...and so it is, on this '88 C4's assembly...
...and so it is, on this '88 C4's assembly...
Last edited by Tom400CFI; 12-11-2015 at 02:30 AM.
