dunchan1

1500 5-spd MT. Carb either floods or starves to shut off. Full kit installed. Needle and seats operating properly..not binding. Gas tank removed and cleaned. Gas lines blown out. New filters. Engine temp proper. Fuel pump checked o.k. Regulator put in gas line and adjusted down to 1# and problem still persists. Starts and idles perfect but after a period of time, it either floods out or starves. Floats are good .. no leaks. Totally baffled. Any answers or suggestions greatly appreciated.

Duane_in_Japan

What kind of choke setup does it have.

dunchan1

Choke is automatic and has been checked for correct operation

Duane_in_Japan

Does the air cleaner have other vacuum diaphrams on it and are they working correctly.

dunchan1

Yep .. Air cleaner has diaphrams and are working properly. ALL connections have been checked and properly connected as far as my mechanic can tell and he has about 30 years experience with Honda.

dunchan1

The baffeling part is, why does the float(s) allow flooding or shut off fuel supply. There doesn't appear to be any binding and needle and seats are new. Even tried another carb top assembly and same result. Could a gas tank not venting properly cause this problem?

thesmogman

Check to see if the float bowl vent is plugged.
Another would be the seal on the accelerator pump.
You might have a bad float too. See if it has anything in it by shaking it.

Duane_in_Japan

If its flooding then the carb is the problem since the seat is not shutting off the fuel, there has to be a vacuum leak allowing extra fuel to be sucked in.

OR your ignition system is getting weak and not burning the fuel well enough and at the other end of the spectrum, its just dying, does the car act like its running out of gas or just dying (when its not flooding).

Can your man amp ramp the coil and the fuel pump, this will tell a major part of the story, does he know how to read an amp wave.

dunchan1

Duane: Flpats are good .. even changed them to no avail. Vac leak could be the culprit. Don't think weak spark is the problem, but will check it out. I'll ask the mech about amp-ramping coil and pump. thanks for the help. Will be seeing the mech today and see what if any progress has been made.
Cliff

dunchan1

At 3# fuel pressure, which is as I understand the proper pressure for that pump, gasoline pushes past one float.. the rear one .. Needle and seat are NEW but suspicion seals or "O" rings are either bad or too small. At 1# or just over, floats hold proper level. Engine idles and revs up beautifully. Super smooth. Suggestion??

dunchan1

Air horn was swapped with another one in good working condition and got same result.

dunchan1

BTW.. What is "amp ramp"? Is it checking the amp draw on the fuel pump?

dunchan1

Duane: I really appreciate your replies on this problem. My mech says in all his years of experience with Honda, he's never run into a problem like this. We do have another carb that we'll install and check out and at least maybe .. if not solve the problem, at least eliminate the carb. Carb float operation is in essence, as simple as the float in your toilet. It either shuts off or it doesn't. This one doesn't.
How does your time compare to ours in the Mountain Zone ..?? Hours ahead or behind?
I'll post any results we get. Any other suggestions you have would sure be welcome.
Cliff

Duane_in_Japan

An amp ramp is todays way of diagnosing, it is a non intrusive test, you do not have to back probe a wire connector or take a chance on damaging a connector or wire.

When you check your timing, you put an inductive pick up around #1 spark plug wire, an amp clamp is an inductive pick up, together with an oscilloscope you can litterally see the heart beat of a fuel pump (in this case), you can see how many amps each little commutator bar on the motor is drawing, you can count how many commutator bars there are around the armature of the motor, how many milliseconds it takes for all the commutator bars to make one revolution and with a little math you can tell the RPM of the fuel pump per minute, this is very important when dealing with fuel pumps.

A doctor can tell on his scope if you have a heart mumer, I can tell if your pump has a murmer the very same way or what ever the problem is, or simply if the pump is ok. With some known good specs you can see if the fuel line is restricted or if the pump is putting out low pressure when it heats up or many issues.

Amp ramping an ignition coil shows a different pattern, its called a shark fin pattern and you can easily tell when a coil is weak by the shape of this shark fin pattern, if it has an internal short, this lowers its power output capabilities. You can see the max amperage or if there is current limiting going on, check dwell and charge time and when the driver turns off to create the actual spark, it may turn off slow, you can see that too.

If your man does not do Amp Ramping, he needs to get up to speed, non intrusive testing will speed up diagnosis 10 fold. Injectors, coils, solenoids, IAC motors and motors of all sorts, even a simple relay has a pattern.

EDIT
I am about 12 ~ 14 hours different.

dunchan1

Duane: Finally!! The problem was in the needle and seat .. we burnished the seats and the needle seated properly and VOILA!! Runs great. I guess kits aren't as true and correct as they used to be. For the cost of the carb kit, this problem should not have arisen. Oh, well .. Seems fine now. I do appreciate all your posts and the help you offered. If there's a kit needed in the future, it won't be purchased at Car Quest.