79RX7IA

At highway speeds 65/70mph in 5th gear i have to use almost half throttle to maintain that speed, and if I floor it the acceleration is extremely poor. I can be doing 65mph and slam the accelerator to the floor and it could take up to 5-10 seconds to hit 70. I'm not sure if this is normal, but im assuming not. Could a small external leak on the carb be the problem?

I'm pretty stumped, as obviously 4th gear is way too low to be driving at these speeds. My acceleration in low gears seems normal, I can easily pull through 1-3 rather quickly.

Jeezus

iTrader: (4)

Secondaries opening?

Scott1982

Are you getting fuel? Carb filters (if carb not rebuilt) blocking? Pump putting out flow needed? Fuel filter plugged? etc. I would disconnect fuel line at carb (and safely and appropriately) measure the fuel flow into a container).

Scott

79RX7IA

The secondaries.. I don't know, Im not much of a carburetor guy so I couldn't really say. The fuel filter was replaced and the problem persisted.

t_g_farrell

iTrader: (1)

Might be the clutch going out. Does it rev up but not increase speed?

Oneiros

could be that your fuel pump might not be up to scratch.

the accelerator pump is known to leak fuel as well, feel around the cover when pumping the throttle (engine off) for fuel coming out.

this is it on the right, the cover with 4 screws

79RX7IA

Its not the clutch, the plugs and wires are new also. Its leaking from the accelerator pump. Would that be the cause?

RustyRacer

Thank you, wanting to know too. Do you have to remove the carb to fix the A/P?

Oneiros

Cracked or worn out diaphragm, which sits underneath the cover.

First try tightening the screws up (remove the circlip and pin to access the lower right screw) and see if that fixes it.

If not, grab a rebuild kit from autozone for $20. If you dont want to do a full rebuild just replace the diaphragm. It's pretty easy, just remove the cover and replace it, but make sure you don't lose the spring and re-install it carefully so that the end of the spring sits on the metal part of the diaphragm.

trochoid

iTrader: (6)

By the time the AP has failed, the rest of the carb itself is usually on it's way out. The AP can be replaced with the carb still on the engine, but why bother. Might as well do a full rebuild and make sure everything is right.

Keith13b

iTrader: (6)

Clogged cat or plugged exhaust? But it does sound like its air/fuel related.

This is an out-there comment, but I just thinking out loud........could your tranny have a bad 5th gear bearing causing resistance and eating power to overcome? How are the high RPM revs in the lower gears? If 3rd gear is happy past the buzzer, that might narrow down some of the possible carb restrictions.

jgrewe

iTrader: (1)

May be you just have a car that is over 25 years old and is a little tired and down on power. 5th gear is an overdrive around .7:1, it is pretty tough to accelerate from 65+ in top gear when these cars a fresh.

If you want to car to jump, downshift.

RustyRacer

I couldn't figure any other way I was getting fuel on my plenum. Also realized my oil cooler line in the back is leaking. Is there a torque amount I should be applying or is it get it tight enough to not leak like a brake line?

trochoid

iTrader: (6)

Most certainly. With the AP pump non-op acceleration can/will be very slow. Any fuel leak should be dealt with promptly. Fuel leaks seem to plague each generation in one form or another. The 12a's it's the AP, the SE's and 2nd gens, it's the pulsation dampener. 3rd gens, take your pic.

With the AP diaphragm damaged/defective, raw fuel is allowed to dribbled directly on top of the hot engine. This presents a serious fire hazard that should be addressed immediately.