Super82

iTrader: (1)

In diagnosing my sputtering problem I checked the fuel pump, my bowls are always full and I have good volume coming from my pump. What I don't know is the pressure. I do not have a pressure gauge but I was wondering, as long as the bowls are filled pressure shouldn't be important, right?

Scott1982

How do you know that your bowls are always full?

trochoid

iTrader: (6)

Pressure is always important whether it be too low or too high. I found a cheap plastic pressure gauge at AutoZone that simply splices into the fuel line. It appears to be accurate as I compared it to the better fpgs that I normally use. It runs 10-12 bucks, iirc

Super82

iTrader: (1)

The nikki's have sight glasses on the bowls and whenever I check they are right where they should be. Even when its sputtering I can look and see that they are full.

I'll look at getting a pressure gauge. So you're saying my pump still could be bad and not have enough pressure even though its filling the bowls-and that could still be my problem?

mjm4jc

You can have, what appears to be, proper volume, especially at idle. If there is a block somewhere in the system (pick-up tube in tank, fuel sock/screen) you can still have fuel volume that will pass the test at idle. What's important to know is if you have the proper fuel delivery under load. You can only know this by doing a pressure test. Search in the archives for "fuel tank clogged" or something like that. Kent, (GSL-SE Addict) helped someone figure out a fuel problem. The car was running like crap but passed the fuel volume test at idle. At fuel throttle however, the engine was not getting the gas it needed due to some crud in the fuel line coming off the tank.

Mike

gsl-se addict

iTrader: (3)

It was the other way around. Passed pressure, but failed volume. The lines were clogged and only allowed enough fuel to get through for idle and would crap out anything above. This was a GSL-SE.

You really need to test pressure and volume. Both are easy to do and the FSM tells you how. Otherwise, you are just guessing. If pressure and volume are good, you know that the pump, filter, lines, etc. are good. Then you will know to look at the carb and related things. You just have to have an idea of what it could be and then test to eliminate things until you find the cause.

Super82

iTrader: (1)

Yeah, I've been doing more eliminating, and so far I've

Swapped Igniters
New Wires
New Plugs
Swapped Coils
Rebuilt carb
checked vacuum
passed volume test
replaced fuel filter

And the car sputters when the car is under a good load, even now when I have the four barrels disconnected and just running the primaries it sputters at full primaries.

speedracer_not

on the right side, there is a cable connection that is very easy to over look. This is the best picture that I could find. you are looking straight down at a spring loaded screw threaded rod. If this is not connected, there will be fuel starvation under load.

Super82

iTrader: (1)

Hmm, that is hooked up, but there could be a difference in how the nut is adjusted. What exactly does it do?

speedracer_not

the mazda mechanic told me that it supplied extra fuel at open throttle.

When looking for the picture on this site, someone claimed to have solved the sputterring under load problem by removing the green fuel check valve in the engine bay. I advanced searched "carburator" specifically in the generation 1 on this site.

Super82

iTrader: (1)

Yeah, I found that one too. I don't have the green check valve the speak of, I just have an orange one that goes to my choke on the passanger side of my carb. I removed that, no difference. The green check valve they talk about goes towards the rats nest, I think, and I couldn't find one on mine.

speedracer_not

check the spark plugs

Red insulators point of lack of fuel. Black point to excess fuel or non sparking (ignition troubles).

Tan plugs are happy plugs.

I assume you are using NKG's and not autolites.

Super82

iTrader: (1)

I put in new plugs a few weeks ago. They became pretty black fairly quickly, actually.

That makes me think that there is a spark problem, that the spark can't keep up with the fuel underload, but I've covered everything in the ignition system. Coils checked out, igniters were good, replaced wires and plugs, hooked everything up right and made sure that timing was advancing. The only problems I got is that the car still runs good with the vacuum advancedments disconnected, and when using the timing light I couldn't get any light off the number 2 rotor.

speedracer_not

rotor and distributor cap, that is all that is left to replace


BTW, on CD ignition, is there anything like a condensor that I should replace when doing tune ups? Is there anything to tune up on the distributor?

mjm4jc

Like the other member said, did you replace the cap and rotor? I don't know exactly how your car is responding, but if there are any cracks in the cap or flaws in the rotor, it can cause the problems that you are describing.

Mike

Super82

iTrader: (1)

No, the one thing I haven't replaced is the Cap and the rotor, and mine are pretty bad. I just figured they weren't an important enough of an item to make a difference. There are no cracks but the electrodes are pretty corroded and worn down. I'll try that next.