Weird Problem

[Curiousgb]

I am experiencing a strange problem. When I fill up my car it will studder/hessitate for a few miles then run fine. The studder usually comes when the throttle is held at a constant usually cruising RPM about 2-3k. If I open the throttle car runs fine. Recently I noticed that the same problem starts when I get down to around 1/4 tank of fuel. Any suggestions?

[Tom @ Fast Forward]

Fuel Filter? How many miles since you last changed it?

[chuckerants]

Isn't there a TSB about the fuel filler thing from Mazda?

Nevermind, I guess I was right and I was wrong.

http://www.miata.net/garage/tsb/fuel_fill_recall.html

[Curiousgb]

Replaced filter about a year ago. I have on in the garage I will will replace it this week.

[Mx5-4me]

When was the last time you changed your plug wires and plugs ???

[Curiousgb]

Wires are less than a year and plugs are new.

[pumpkin]

Could it be water that is stirred up when you fill. THen when you get down to nearly empty it picks it up again.
Try some dry gas additive.
JD

[Tom @ Fast Forward]

Could it be water that is stirred up when you fill. THen when you get down to nearly empty it picks it up again.
Try some dry gas additive.
JD

Water is heavier than fuel and would stay at the bottom. However, the fuel pickup is also at the bottom. So, if there was any water, he would suck it up first.

[Mathrips]

Did you wash your engine and get some water in the plug holes?

[Kyp J]

Not having any idea how this part works (or not), isn't there something about the recirculation of fumes etc. that makes a tightly sealed tank necessary, and some situations where if it is left open causing functional problems?

With that in mind, is there a possible scenario if some part of that is acting up, the process of putting in gas is changing it's environment for awhile causing a disruption in the ECU's compensation that had been going on before the cap was loosened and also, that compensation is becoming inadequate to manage when the tank is getting low.

[Mx5-4me]

Not having any idea how this part works (or not), isn't there something about the recirculation of fumes etc. that makes a tightly sealed tank necessary, and some situations where if it is left open causing functional problems?

With that in mind, is there a possible scenario if some part of that is acting up, the process of putting in gas is changing it's environment for awhile causing a disruption in the ECU's compensation that had been going on before the cap was loosened and also, that compensation is becoming inadequate to manage when the tank is getting low.

if there was a pressure issue in the tank it should throw an ECU code ..

[Curiousgb]

It is not throwing codes and I tried to duplicate the problem by opening the tank to simulate filling up. Didn't happen. I am going to change the fuel filter and open up the tank this weekend. Maybe I will find something...

[elerner]

It is not throwing codes and I tried to duplicate the problem by opening the tank to simulate filling up. Didn't happen. I am going to change the fuel filter and open up the tank this weekend. Maybe I will find something...

Tip: Don't use a match as a flashlight to take a look in your tank! ;)

[Curiousgb]

Been there done that.......No hair, eyebrows.....

[Kyp J]

It is not throwing codes and I tried to duplicate the problem by opening the tank to simulate filling up. Didn't happen. I am going to change the fuel filter and open up the tank this weekend. Maybe I will find something...

How about a fast slollam (?) to simulate the agitation of incoming gas.