Is 300 miles to a tank of gas good for a 84 GS with no trailing spark???? What size gas tank would be in my 84????

 

I think an 84 will have like a 17 gallon. someone else might know for sure.

 

no last time I was on E I put in 13 gallons

 

Well, it's not uncommon for the gauge to read E and still have a few gallons left in the tank.

 

According to my Haynes manual a 1984 RX-7's gas tank is 16.4 gallons bone dry, but when my GSL-SE has half a tank it only takes 6 or so gallons to fill it.
Next time you totally fill up, set the trip mileage, then when you refill see how much gas it takes.
My 1984 GSL-SE gets 22-23 mpg and I consider that good mileage for what I've heard..but then you have the 12a and I have the 13b...

 

My 84SE only gets about 17 in the city (A/C running), and about 20-22 on the highway (A/C running).

The Mazda factory manuals list the fuel tank at 14.5 US gallons, so that should give you some idea of what kind of range you should be getting. Be thinking about 'usable' fuel however, since running it in the last 1/100th of the tank is going to bring all that gunk through the system and cause problems for you in the long run. Plus, the fuel pump is cooled by the fuel flow, so if you're recirculating the fuel, it's temperature is going to go up and the pump temperature is going to go up, accordingly.

I usually refill at about 1/4-1/8 of a tank, rarely less than that, and my odometer usually reads about 230-250 miles. I haven't run out of gas since I was a teenager.

 

Long duck, your manual may be right, I'm not sure of the accuracy of the Haynes manual on this. But the Haynes Manual says it's 14.5 gallons for up to 1980 models, then 16.4 for 1981-1985. I think the Haynes manual is correct because they got rid of the full size spare for 81-85 to get a bigger gas tank.

 

Damn, I only get about 13 MPG on my 82 GSL. Although I have emission removed, no cats, and running on some headers. Maybe I am in need of a serious carb rebuild or maybe..I am running way to rich.

 

Well if its 14.5 then I get about 22 mpg and if its 17 gal then I get about 18mpg. I say that is pretty good from my old 7(about 11 mpg on a good day, big turbo does that )

 

i feel your pain brotha. i got the same **** to deal with

 

You really need to fill up, then keep track of how many miles you've driven and see how much gas it takes to fill up.

Because even if you're tank was 16.4 and it was on Empty you probably had 2-3 gallons left.

 

Agreed. To accurately estimate MPG you *must* reset your trip odometer on one fill-up then measure the amount it takes to refill it the next time. No need to run the tank dry or even close. If you drive 50 miles and it takes 2 gallons to top it off, that is 25mpg. Very easy.

As for the size of the 1st gen tanks, the 14.x and 16.x specs are right, but the full capacity is not able to be used...air pocket at the top and a "pool" at the bottom. My 83 with the 16 gallon capacity tank can use 14 gallons total in practice. I've owned five 1st gens and that seems typical of the latter ones.

My almost stock 83 GS gets a solid 30mpg on the freeway on long trips and about 18mpg around town...hell, my old peripheral port 13B with Weber 51IDA at 4.88 gears got 15mpg pulling a trailer and 19mpg without! Tuning and proper maintenance is, obviously, critical.

 

I get 18-19 mpg on my T2--about 50/50 highway/city.

Usually that's about 265-275 miles on a tank and about 14.5-15 gallons a fillup + 14 oz premix.

 

Over the course of 5 yrs driving to and from school (50 miles rd trip/day) when I was in college, my 84 SE got around 18mpg. On a 400 trip with one fillup in the middle, I avg. 20mpg. Most miles I ever got out of one tank was 278miles and it was on empty practically. I don't know how others get over 300 in a 7....