Help! Need some advice on a Sending Unit and Fuel Pump

[Rockey]

Hi Everyone,
I am a new member and could use some help! I am replacing the sending unit in my 84 corvette along with the fuel pump. I have read that you can replace the 84 fuel pump with a 1985 fuel pump. I understand that that it delivers a higher fuel presure? Can you replace the entire 84 sending unit with an 85 sending unit? (Maybe a dumb question) Do any of you know where I can find a sending unit more affordable than $300.00? Thank you for taking the time to answer and explain.

 

[Towu4free]

Hello, and welcome to the CAC

you will find many helping hands here as i did. as for your question, im not to certain about the early model C4s' but i would imagine like my 94 that the fuel pump may even be the same.. the fuel pressure regulator would be the item to go after if you wanted more fuel pressure because regardless youll sustain the same pressure as long as the regulator is set to the 84 specs.. as far as pricing i didnt replace the sending unit in mine i just did the fuel pump and regulator (had a hard start issue) and the fuel pump didnt cost much, Many will agree with me when i say buy OEM when you can however Acdelco is'nt GM this is a common mis conception with people a GM part is diffrent than Acdelco,anyways before i ramble on i bought my fuel pump at Advance Auto parts i work there and i was able to get my discount on it but the reason i did go with it is because for 1 it has a Lifetime warranty (thats always a good sign) and 2 on these C4s the fuel pump is very very EASY to change!! well my friend again welcome to the CAC and im sure others will chime in with more detailed advice for you! ALSO check out the site...there are some partenerships with corvette parts and such and sometimes you can get a discount!

 

[Hib Halverson]

I've heard of people with modified 84's upgrading to the 85 pump, but you don't need to do that unless the engine is modified such that it needs more fuel flow.

If the car is stock, I'd suggest a replacement with a stock pump and sender assembly along with replacing the fuel filter.

 

[nelson84]

If you plan on doing modifications in the future put in the 85 pump. You will need the extra fuel pressure if you install the new renegade intake manifold from "Dynamic crossfire solutions". This new intake manifold is a direct replacement and everything bolts up to it and it lets more air into the engine and it gives you 33 hp and 16 lb/ft of torque at the rear wheels.

 

[Schrade]

What pressure are you showing now? Did you check under all conditions (static, motor on vacuum ON FPR, motor on with vacuum OFF FPR, and pedal down pressure (on the road, gauge taped to glass)).

 

[CorvetteArchives]

I've heard of people with modified 84's upgrading to the 85 pump, but you don't need to do that unless the engine is modified such that it needs more fuel flow.

If the car is stock, I'd suggest a replacement with a stock pump and sender assembly along with replacing the fuel filter.

I disagree. The 84 pump is only rated for 13 psi max.
I replaced my aging 84 pump with an 85 and it makes a WORLD of difference.
Granted you could say that the old pump was weak and replacing with a new 84 may have netted the same result. Using the stock 84 pump also presumes the pump is always operating at peak efficiency. However, rarely does this happen in the real world especially in the future as the pump ages.
Furthermore, many folk have determined that a stock CFI runs best with the fuel pressure at 15 lbs. I currently maintain a stock fuel pressure setting on my own CFI so I cant tell you first hand if that is the case.

 

[Rockey]

Thanks everyone for responding (a lot to think about). The engine is stock, the intake is stock. I may change the intake at a later date. I did read some comments on this fourm on the Renagade Intake, last I read that the company was looking for pre-orders. Was it ever produced? I thought I would get some suggestions since I am replacing the entire sending unit. My car was in storage for 17 years with a full tank of gas! I drained all of the fluids except for the gas. I just plain forgot! (It is a long story that I will share with everyone at a later date. My brother and I are working on getting her back on the road. I will post photos soon!