Searched and couldnt really find exact issue but last night on the second test drive since the revival finally went more than quarter throttle and while accelerating in second gear at about half throttle once around 3k the engine started bucking until I let off the throttle. Places to start? New parts on car factory mazda cap and rotor, spark plugs, coolant temp sensor, and fuel filter all mazda. Ignition system? Fuel system/pressure issue? Need some help from the SE gurus. Thank you for your time.

 

Have you been working on or near the TPS?

That can do it I found recently. Finicky little bugger.

 

Ok I think im possibly having a lack of fuel pressure at higher rpm. Need to hook up a inline guage tomorrow and see what is really going on but I have a constant very loud buzz sound at the fuel pump? that's mounted on the small skid plate on the drivers side rear with the fuel filter. Is this a fuel pump and possibly internally worn making noise and not pumping full pressure? And what is spec fuel pressure range for a SE?
(Injectors are good as they just got back from witch hunter, new plugs, cap and rotor, new wires will be here this week. But im still kinda thinking fuel?)

 

There is a wery small filter that goes into the inlet side of fuel pump itself make sure its clean or it will couse a whole lot of problems

 

is the filter replacable or do you just clean it? also would the filter come with a new fuel pump? and still trying to find the fuel pressure spec

 

Found the gsl-se fuel pressure spec thought id share it's 49.8-71.1 psi

 

you just pull it out and clean it its like a cone shaped mesh its very small and you can loose it if your not careful but if that thing is clogged up you it will give you all types of hell.

 

bad FPD?

 

Fuel Pulsation Damper? Im guessing and this is the thing located on the end of the fuel rail? if so when i put my injectors back in i pulled the plastic cap off and found the screw with the small o-ring in the cap, i put the screw back in the fpd and ran the motor no leaks around the fpd. I have seen people putting a banjo bolt inplace of the fpd dose any one have a link to but said bolt and washer? and would this cause issue?

 

Few things:

That fuel pressure spec is that of the pump (deadheaded). With the regulator in place, it will be around 28 psi at idle, about 37 psi at WOT.

A fuel delivery problem usually causes it to lean out/die with a higher load. The bucking sounds like the TPS to me.

Before testing fuel pressure, i would test fuel volume. Get an empty gallon jug, stick the fuel feed from the engine bay in it, turn key to 'ON', push open the AFM door (under air filter). Fuel should start to flow. Time for 1 minute. The gallon jug should be close to half full. If it is much less, there is a blockage somewhere. I've seen a blockage so bad to where the car could only idle. Try to drive (even on the driveway), would make it stall. The FP also made a lot of noise. Fuel pressure was okay at idle, but if you left the tester connected, you would see it drop like a rock when to tried to drive the car.

 

you could have bad cats or leaking fuel injectors. I am having the same issues with a GSLSE I just bought. I adjusted the TPS, even though it runs a lot better, I feel something is holding it back. I don't feel the exhaust free flowing out of the muffler like like my other RX-7's. I also smell fuel at idle.

 

Ran pump for 1 min and only filled about 1/8ish or less of a gal, so must have a huge restiction. while cranking fuel pressure is around 30-35psi and dead head system pressure pegged my guage at over 50psi so pump must be pumping but very very little volume. Both injectors passed the leak test as they both just got back from witchhunter performance in WA

 

deffinetly pull the pump out or atleast the line that comes from the tank to the back of the pump and check that screen then. If that doesnt fix it you might have to drop the tank and clean it theres a screen in the tank that rots and falls apart and all the crap in the bottom of the tank clogs it up.

 

In the bad one that I saw, the pickup/return tubes in the tank were nearly completely blocked. We probably got like 8 oz in one minute (if that). It was enough fuel for idle and to hold the proper fuel pressure for idle, but not much else.

You could repeat the test at the pump outlet. That will tell you if the problem is before or after the pump. If you find it is before, check the inlet on the pump and the next step would be to drop the tank. It is also a good idea to replace your fuel line back there. They have probably never been touched and often will be spongy or cracked. Easy to change with the tank out.

 

Finally got a running fuel pressure test at idle its at 30psi while driving and watching guage once bucking starts pressure drops to 20 the second you let off the gas pressure comes back up so big restriction. So I just went to the tank pull first and found the issue pick up filter totally clogged and pick up tube and return tube are to full of rust. Im not sure if they could be cleaned out anyone know of a place selling the pick up /return line assy. that goes into the tank? Sender looks totaled also. And I was guessing I could powerwash the tank out but its bad and full of rust chips so its going to a fuel tank shop to see what they can do for it.

 

this is what I did same problem car sat for 8 years and was parked with a full tank of gas. I dropped it went to home depot and got 2 gallons of muriatic acid stuff sold for etching concrete. First I power washed the tank it took a lot of that stuff out but not all. Then I filled it with water about half way and then put one gallon of acid in there YOU HAVE TO PUT WATER IN FIRST trust me on that one if oyu put acid in first when you go to put water in it it will splash on you and that will hurt like hell. Anyways let the tank sit for a day slosh it around pour all the stuff out do it over again with less water and about half gallon of acid this go around cap the tank slosh it good pour it out rinse with water real good and then dry it out in the sun and you should be good to go.

 

I love finding these old posts. Having this issue right now. I am going to start with checking the fuel filter first, which I suspect is clogged. If so, I have some work ahead of me dropping the tank.