[Goodbar]

I am still having the same issue starting the car when it has around 170 miles after a full tank. It acts like fuel is not available. I have to crank it for about 10 seconds before it starts. There is no problem when the tank is full. Fuel empty light also comes on about this time. I replaced the fuel pump when this issue started. There is some issue with the fuel tank sending unit and the fuel gauge. Car runs normally after starting, around 24 mph.

What does this add up to, and what to fix ? Could the faulty fuel tank sending unit be causing the whole problem ? They don't make or sell that part anymore at Mazda.

 

[Spannerhead]

How old is your fuel filter? Could potentially be the FPR also that has a check valve that holds fuel pressure for quick startup.

 

[Goodbar]

Fuel filter changed, so some other issue. FPR, I don't know, I will test it.
This whole thing started when a shop replaced the fuel pump a few years ago. I had the fuel pump changed out recently,
That helped some, but did not take care of this particular problem. Before I changed out the fuel pump recently, if I would go around a corner at speed, sometimes the car would shut off......lack of fuel. Maybe the shops never put everything together back correctly, but I don't know where to look for the problem.

 

[Spannerhead]

Does the fuel pump assembly have a particular orientation in the tank? Maybe they installed it backward and the pickup is on the opposite side of a baffle, which causes the fuel to slosh away from it. Did it happen more going around left- or right-hand corners?

 

[Goodbar]

I think it happened either left or right. Not very often, only when a relatively fast corner. The car would immediately shut off. Then I could restart it right after that. I would fix this myself, but Mazda no longer has the part. I have a fuel sender I got from a 1999 Maza 626. I would install that and see what happens, but I can't tell if it is the same part. The diagrams from Mazda for both the 1994 MX6 and 1999 626 look the same. I don't want to go to all the work of dropping the fuel tank, only for the part not to be a proper replacement. I don't know what else could be causing this current problem.

 

[Mazda_Powered]

Check fuel pressure, if it's within factory spec then move onto.....the distributor. Btw year/make/engine helps

 

[Goodbar]

1994 MX6 2.5 l v6

There is no issue with the car performance. 24 mpg, runs great. Only issue is when the fuel tank gets about half empty, it takes about 10 sec cranking to get it to start.....definite lack of fuel for 10 sec. Empty fuel light comes on. New fuel pump 2 months ago. That is why I think the only issue can be something with the fuel tank sender causing it. Fuel gauge does not show proper amount either. When tank if full, gauge only shows about half full.

 

[patrickthomas11]

What is the fuel filter's age?

 

[Goodbar]

I changed that out too when I got the new fuel pump, about 2 months ago. The new fuel pump eliminated the problem when making a sharp turn and fuel starvation from sloshing. Nothing has helped regarding the fuel delivery starting up when the tank is half full or less....takes 10 seconds of cranking. Fuel gauge never shows full after a fill up. Fuel light comes on when tank is still half full. Other than these issues, car runs great. I think somehow the shop did something incorrect about 2 years ago, when I had a new fuel pump installed at that time. My only guess is the fuel sending unit in the tank is messed up.
But Mazda no longer has this part, and I have not found one at the junkyard except from a 1999 626. Which I can't tell if it the same part as for the the 1994 MX6. Diagrams looks the same, but I don't want to drop the fuel tank without knowing for sure I have the correct replacement fuel sender.

 

[Goodbar]

The fuel tank issue remains a mystery. It is almost like my fuel tank shrunk to half its former size.

Car runs perfect
24 mpg average
After filling up, fuel gauge goes to just over half full
Car runs great until about 180 miles, then takes 10 seconds in the morning to start up from fuel starvation
Fuel gauge is now showing empty
Car still running great

Fill up and start the process over again

 

[fredtw0]

Is it possible that it stops filling around 50%? I once had a car with a bad filler neck, little flap inside would prevent filling to full

 

[Goodbar]

That is interesting. How to look for the little flap ? And how to correct it ?

 

[fredtw0]

Idk... Maybe it wasn't the neck itself .. where the neck clamps to the tank. I think maybe on the tank side. In my case, the pipe was deformed and no longer round. The round flap would get caught. It is supposed to prevent the fuel from sloshing out, I believe.

 

[Goodbar]

Actually I have seen some fuel spill out after filling up at the gas station. Would this be a hint of the problem you mention? Or unrelated, and just meaning the shop did not put the filler tube part back on properly ? But also, I had this issue with the fuel tank before this shop worked on it and caused this new problem.

 

[fredtw0]

Not sure about timing .. I would just take a look at that neck where it attaches to the tank and see about its roundness. Maybe use a channel lock to squeeze it round again. Be careful, too much squeeze could make it worse.

If someone was to take the neck off again, you could validate the flap is moving freely as I recall

 

[matt89glturbo]

The flap is right before the filter neck meets the tank, and is possible to have the hose twisted in such a way to bind up the flap. In my case, my flap wouldn't allow fuel in very fast, so had to fill it up barely holding the trigger open. If the tank wasn't fully dropped to change, could easily cause the filler tube to twist. Our tanks are plastic, so advise against using channel locks on the connection, if out of round, should be fixable by fixing the hose going in. Worth giving a good visual inspecting around the tank, and if nothing found, they're relatively easy to drop, one of the easier ones I've done, if in a rust prone area, might change the simplicity, though.