jose7740

I just ordered the 1985 sending unit for my 1984 Vette, there should be no problems with compatibility, right? I want to take advantage of more powerful pump of the 85 unit compared to the 84 one.

jv9999

Not a good idea. The '85 pump has about 2.5X the pressure.

jose7740

According to CF senior member Hot Rod Roy, there is no problem because the regulator will handle the new pump.

corvetteronw

Read this:https://www.corvetteforum.com/forums...re-engine.html

Hot Rod Roy

If you compare the fuel pumped by an '84 pump, with the fuel pumped by an '85 pump, with the fuel flowing into a bucket, the fuel pressure will be the same for both pumps . . . zero! The pressure is a function of the pressure regulator, not the pump. The '85 pump has a higher capacity, and the use of an '85 pump in the '84 is a very popular modification.

A garden hose is the same idea. There's no pressure in the hose until you put your thumb over the end of the hose!

Here's a thread with some other discussion on the subject:

corvetteforum.com/forums/c4-tech-performance/3751977-fuel-pump.html

jv9999

If there was no pressure, no water would flow. Also, there is no regulator in most garden hoses.

jose7740

As soon as I get that new unit, I will post how does it works

jose7740

Today I installed the new pump/sending unit on my 84, the car started right away, no leaks, accelerates good on the lift, I will not be able to road test it until I finish the brakes, right now it looks like I will need new front steel lines since the nuts on the brake hoses do not want to come out and I already damaged the nuts, hopefully I can find them, will let you know how the car runs with the new pump/ sending unit as soon as put it back on the road

jkann1

Hi, I just bought a 84 c4.. I don't know anything about the crossfire injection.. it has 2 flaps on the air breather they are open before I start it and when I start it I think one closes the other stays open it a rough idle until it warm up ... after warm up it runs smooth.. is that normal .. I know it shouldn't idle rough what kind of problem am I looking at... or any suggestion I really thank you for your time...

jose7740

Both flaps are open when the engine is cold, when you start the engine they are supposed to close and open gradually until hot, check for he vacuum hose under the air cleaner to make sure a hose is not broken.

jkann1

Thanks.. I will check them out