Vienna

Does anyone know of someone in Arkansas who knows how to work on my car? Briefly, when I'm driving, the car's power drops to a standstill, but the car doesn't die. Pressing the accelerator does nothing until after a while the car gets its power back and then is fine until the next time. No one in my small town will touch it! We have replaced the fuel pump and fuel filter but not the screen in the gas tank. I will appreciate any help you can give me. Thanks!

t_g_farrell

iTrader: (1)

Does the new filter have a lot of gunk building up in it? Could be crud in the tank as well.

Ckforker

You might drain the tank, it should have a drain plug. You can see what comes out from the bottom.

Are the float bowls filled? Both front and back of carb.

Have you checked for flow post pump?

If all this checks out, you might need to rebuild the carb or have someone do it. I know there's some on here that will rebuild for you, hopefully they are still around.

Vienna

I don't see gunk building up, but I've wondered about the tank, as you mentioned. Thanks.

Vienna

I will show your reply to the man who works for me. Since replacing the fuel pump and filter didn't help, we have wondered about the carburetor, but no one here has the skill to work on it. I was hoping someone on the forum might accidentally know of someone in Arkansas that I could contact. Thank you for giving me some ideas!

Ckforker

I did mine after much consternation, but after getting into it, it wasn't that bad. prep work is absolutely key to a successful rebuild.

GSLSEforme

Before you pigeon hole yourself into the problem being the carburetor,check fuel pressure and volume. This sounds like a fuel to the carburetor problem. The carb can't turn off flow of fuel other than at idle,it can run out of needed pressure and volume under power and initiate symptoms you state and still allow car to idle.

What kind of fuel pump did you put on the car? Strongly suggest you put an oe Mazda fuel pump on car-it may not be responsible for your exact problem-at this moment but is only pump on stock car/carb that feeds the Nikki carb exactly the fuel/pressure it needs. This carburetor is very sensitive and putting on a parts store aftermarket fuel pump can add driveabality problems you don't need. Many here will chime in and attest to this.

You can do a 1st test yourself. Take a short 2 minute drive and shut car off.Take off air cleaner so you can see carburetor. It has two windows that show exactly how much gas is in the carburetor bowls. The level of fuel should be 1/2 way up window in both carburetor bowls.
Possible you may need to wipe dirt from sight windows and you will need a mirror to view the rear bowl window fuel level. Drive car until it comes to a standstill as you say and pull off the road,shut engine off and pull air cleaner off and inspect level of fuel in windows. If fuel level is down or none shows,the problem is fuel supply-car can't run without fuel.

Likely the fuel tank has debris and gunk floating around in it that gets pulled up on feed line and starves fuel pump and carb,this has happened to many of these cars. The gas tank in your car is no different than any other gas tank so your mechanic will be able to remove/inspect to see what's inside. He will know a radiator shop that can cook the tank if it's not too rusty and put a coating in it to prevent recurrence of rust and reinstall with new fuel hose/filter/correct pump. Flush metal feed and return fuel lines and replace original fuel line with ethanol friendly hose. Your car should run as new.

DummyFixer

I had a experience quite similar with my nearly new '79 S. My two sons had "borrowed" some gas using a "tubular credit card". Problem was, that they dropped the hose into the tank. It rolled around in the tank and when it got directly over the pickup it would stop the flow of fuel. As soon as the car was shut off the hose would roll away from the pickup and everything was normal again. I had to remove the tank to retrieve the hose.

Vienna

I will relay your suggestions to my assistant/mechanic. Many thanks!

Vienna

Thank you for your very detailed reply. It's all over my head, but I will show it to my assistant/mechanic. The car has had excellent care over the years and drives like when it was new...until this happened. Currently, I just have it sitting in the garage because it's too iffy to drive.

jkmcafee

I had the same problem with my 85 GS w/ 12A. Recently posted some pics that show what I did to test fuel pressure (~3.5 PSI) and fuel flow (~1.5 qts/min). Although I have not had time to drop the tank and fix the actual problem, blowing out the supply line back toward the tank made a huge difference and fixed the symptom. I will post more once I fix root cause which is related to the tank itself.

In my case, previous owner had installed a clear filter near the carb. Although I plan to remove it once I fix root cause, it sure comes in handy once you know what good fuel flow looks like - same concept as pulling the air filter and looking at carb bowl sights as others have mentioned.

Good luck!

Vienna

Thanks for this information. How do I find those pictures you posted? We have blown out the fuel lines, with no improvement. I also have a clear filter that has been moved to under the hood. We checked the windows of the carb and found the front window fuel line at about one-half and the rear window to be more than one-half. On a test drive, when the problem showed up, my mechanic found the front window to still show a fuel line of one-half. He was too frustrated to remove the air filter at that point, so we don't know what the rear window showed. We also went to a muffler shop to discuss the catalytic converter; the man there said it was definitely not that.

Currently, a friend of mine who knows a lot about cars drove my car around town (with me in the car] and his verdict was that my problem is the carburetor. No one in my small town will touch it.

The problem doesn't show up in the first few minutes of driving. The power loss is on inclines, though you can detect there's a problem when you come to a stop and then start to go on flat terrain. There's kind of an irregular bumpy feel; I refer to it as a rub-board sound. The car will do this and then go on just fine...until the next time. Thanks for listening!

rxtasy3

iTrader: (2)

if u click on his name there will be a menu with "find more posts by jkmacfee".

jkmcafee

https://www.rx7club.com/1st-gen-gene...ssues-1140726/

jkmcafee

Vienna, in my case I had way too many variables to deal with because I bought the car and I wanted to verify what previous owner had said. He supposedly had cleaned and sealed the tank, replaced the fuel pump, removed and cleaned the carb, installed two fuel filters, etc.

Since it all starts at the fuel pump, i wanted to see if the new OEM fuel pump I installed (I tossed the aftermarket one the previous owner installed) was able to pull gas from the tank with good fuel pressure and good fuel flow. As it turns out, it could not. Pressure was good but flow was awful.

I then tested to see if the fuel pump could pull from a clean gas can. Worked fine. So this isolated the problem to something back toward the tank and not toward the carb. I removed the cut valve between the tank and filter and blew the supply line out back toward the tank. I realized I may be blowing crap back into the tank but at that point I knew I had to drop it anyway. Hooked it back up and the fuel flow was great. Amazing how much better it works when the lines aren't restricted.

I then cleared the supply and return lines from the fuel pump back toward engine (disconnected from carb of course) and re-tested at carb. Although I will remove it, the clear fuel filter near the carb installed by the previous owner allowed me to see what "good" fuel flow looks like. There was a huge difference so I had confidence that I had made a diffrence.

Test drove the car and it ran great. Some other minor issues I'm still dealing with, but the stalling and fuel starving problem was fixed.

Next I plan to drain the tank and look at the fuel quality. Then I'll drop the tank and see what's going on inside. More later once I get to that point.

Carl

iTrader: (2)

Had a similar problem during a race just before Thanksgiving. It turned out the carb was flooding most likely due to a stuck open needle valve or float. Don't know which, but too much fuel is as bad as too little.