jjaesmith

Need help!! Last summer I put new plugs and wires in my 7, and since then I have a hesistation when on the throttle, then about three weeks ago I was on it hard and it bucked super hard, but hasn't done it since. I have replaced the fuel lines and fuel filter since and now I am wondering if it could possibly be the fuel pump. I don't have water in the system I have ran plenty of Heet through it. I thought it could be a vacuum leak but all my vacuum ports are capped with new caps and tight. Any other suggestions.

RXSpeed16

iTrader: (41)

Give some info on car setup, year, turbo/NA, modifications.
If turbo, you may have hit the stock ecu fuel cut when it was cold outside.

jjaesmith

87 Non-turbo street ported, no major mods

RXSpeed16

iTrader: (41)

There's a fuel sock before the pump that can become clogged. It's attached to the fuel pump assembly and accessible through the trunk opening. Usually causes engine stumbling when turning.
-Make sure the wires are connected correctly. Trailing on top, Leading on bottom. Rotor 1 front, Rotor 2 rear. Check for spark.
-Could be the 3800 rpm hesitation and it needs some ground repair.
-Check the voltage at the fuel pump.
I'm just throwing ideas up to get the ball rolling. Don't go crazy changing parts just yet.

Molotovman

iTrader: (49)

[quote=jjaesmith;9779033]Need help!! Last summer I put new plugs and wires in my 7, and since then I have a hesistation when on the throttle[quote]

So, how did you check to make sure you put them in right?

And is what you're trying to say "Last Summer, After I put new plugs and wires on my car; I immediately got a hesitation"?

jjaesmith

I know the wires were put in correctly because we did one at a time kinda hard to mix up the leading and trailing when you take em off individually, and no it was not an immediate hesitation, thats why I am leaning towards a fuel pump issue. I am going to try putting 10mm Mazdatrix wires in and seeing how it feels then. i think at this point in the game, its a safe bet to change to a better fuel pump, not an Airtex like you can get at autzone and oreilly.
All the grounds in the car are in good shape like i said the engine is barely 3 years old and is well maintained.

tIIsleeper

what rpm does it occur at and is it sporadic? or just just once and its done?

jjaesmith

all rpms and its consistent during acceleration

RXSpeed16

iTrader: (41)

Is it load dependent? Does it act the same when you rev it in neutral as it does when driving it?
-Maybe a wire was bad out of the box.
-Have you pulled the plugs to see if you are running lean?
-I think you are on the right track with fuel, but maybe you had a bad tank of gas and the in-tank fuel sock is clogged. Have you taken a look at it yet?

ItsFun

iTrader: (25)

I have the same problem myself. Mine is load dependant( no prob in neutral) if you give it a quarter throttle will it get you up to the redline?? I am able to do that with mine. I regrounded my 3 grounds and had a little improvement so try that. If im not mistaken s4 na needs backpressure from exhaust to operate the aux ports, maybe you are experiencing something like that. Try putting some grease on the aux port shaft and give her a spin at 1-4 or 1-2 throttle trying to get above 4k and see if the ports are working (you should see movement in the grease. Flame me if im all wrong but that can help diagnose. Im at the point where i think it may be my ecu that is failing. Hope you figure it out for you sake, and well for mine too cuz id like to be running normal again.

ItsFun

iTrader: (25)

Also I notice that when i first take off under load on the road I will have no problem in 1st gear with the hesitation but i notice if i cycle all my gears and get it back into first and try taking off again it hesitates. Let us know how its acting, or not reacting to diagnostic attemps.

jjaesmith

Not a bad tank of gas I have ran several bottles of Heet through since this has started, I am starting to agree with the bad wire and it running lean, I bought my wires from work and there is a good chance there is a bad one or the size wire isn't good enough, I think i am just gonna do a mass change and replace, wires and fuel pump and see what happens, a better fuel pump than the original would put my mind at ease anyways and the wires I have are cheap and don't go with the look I am going for. Lesson learned not always good to skimp not even on wires

Amur_

Instead of throwing money out the window, why not do some troubleshooting and minimize the expense? You can download the factory service manual for free from several websites. Decide what you want to test and it will show you how to do it.

Have you tried to pull error codes yet? Good place to start.

http://teamfc3s.org/info/articles/errorcodes/main.html

jjaesmith

It's not throwing money out the window, I have been wanting to get a new fuel pump for sometime and I want to get 10mm wires this just is pushing me to do it sooner. Plus I got the gigantic shop manual, and my dad who is pretty versed in rx7's he thinks its good to upgrade to a new pump, just like getting a drive shaft with removeable u-joints is a good idea. I am going through my car, I don't wanna wait until I am on the side of the road, basically I am just making sure I am not missing something or seeing if someone else is having the same issues.

boyscout

I have the same problem in 2nd 3rd and 4th gears. not in first or 5th but at about 3500 rpm it hesitates. one way to check your fuel pump is to take off the return fuel line at the "H" connection, attach a piece of fuel line long enough to reach a gas can on the ground. Have someone start the car and see how much gas comes out. then turn the car off and put the gas back in your tank.

boyscout

Does your tachometer work? mine cuts in and out but mostly doesn't work and when it does the 7000 rpm buzzer goes off. I'm looking at grounding or a short somewhere.

jjaesmith

Ya my tach works and i hate that little buzzer because it goes off when either the tach or the speedometer doesn't work

NewRXr

86's and 87's N/A have a small restrictor orifice in the vacuum hose going to the boost sensor (that's what Mazda calls it, I call it a map sensor). This small little pill is installed in the vacuum hose just before it goes onto the vacuum nipple. If you ever replaced that hose or had to cut the end off to reseal it there's a good chance the restrictor is gone. Look at that hose and see if it still has a white band around it just off the intake nipple, this is how they marked the hose. If it doesn't pull the hose off the car and try to blow through it. If you can blow right through the hose easy the restrictor is gone and that's your problem. On those two years they put the MAP sensor hose on a single runner instead of a plenum, so the vacuum signal is constantly pulsing. With the restrictor in place the vacuum level in the hose is held more constant. This is what they programmed the fuel injection with, a steady signal. The pulsing vacuum will ruin heavy throttle accelleration in every gear but first is not so bad. Don't ask me why.

I just replaced my fuel pressure pulsation dampener and ended up with the same problem you're describing because I incidently cut out the restrictor orifice to make a clean end on the vacuum line when it tore moving the intake aside. It wouldn't come loose so I just left it on then it tore open so I had to fix it. I did plugs and wires, the pulse dampener, cleaned out the intake and a few other things so it was pretty confusing. I knew I did everything right so I thought it was a check valve we had reinstalled after it broke and we glued it a while back. I was digging through Mazda TSB's for 86's and came across the problem described exactly and that this could cause it. On the way to work the next morning I rembered cutting off the white band section of a hose because the hose wouldn't go down after I cut the torn part off and it was stopped up with something.

Good old Mazda still sells parts for anything it ever made it seems. So $2.37 with overnight shipping later the parts guy can't believe he's delivering a black spec smaller than a fly and wants to know what the heck it is.

I put it in and it runs better than before, because of the tune up I suppose.

I have the part number at work, if needed.

Vernon

jjaesmith

very interested in the part number and where you ordered it from

NewRXr

I ordered it from Justin, he works the parts counter at Gullo Mazda in Conroe Texas, 1-800-9-CONROE. I can get the number off the invoice tommorrow. But if you know a good Mazda parts guy describing it exactly as I have to them will get you there. That's what I had to do because the old TSB didn't have part numbers on it but he found it pretty quickly. It helps a lot if you have your VIN# ready for them to search from.

Vernon

NewRXr

Part# 8931-13-986 Orifice

Vernon

ItsFun

iTrader: (25)

I would not upgrade a fuel pump on a na, stock is more then enough. If you think your running lean an upgrade on the fuel pump will make you run way to rich. Interesting on the resister.... I will have to check to see if mine is gone! I have never heard of that one before.

jjaesmith

Well I have nixed the idea of a new fuel pump I have like 2 spares sitting in the garage, so if i need one I am covered. I am going to remove my piece of crap work plug wires and put on Mazdatrix 10mm, I am really starting to think its a bad wire. In other news I got the rear window louvers, yeah many of you are probaly turning ur nose up to them but its a personal preference and I live in Atlanta and my rear hatch is like an oven in the summer. I am also set up and ready to go to do my 5-lug swap next weekend. After this all I need is a coat of paint and to re-do the interior