mazdaverx713b

iTrader: (91)

what are the symptoms of a failing accelerator pump? how will the engine behave and are there any symptoms that are readily apparent other than the pump actually leaking?

Rx-7Doctor

iTrader: (13)

Should be stumbling or hesitation under initial acceleration

Bigmotoxer

Docs right...I just went through that. My accel pump was hard and crispy...it stumbled when you pressed the pedal then it ran fine after that.
And of course if you remove carb and rebuild it don't take squirter screw out and blow the weight and ball out in the yard like I did It's fixed now though

Rogue_Wulff

In addition to what doc said, most of the time, when they get bad enough to start the hesitation/stumble, they will start to leak rather quickly thereafter.
If it is leaking, it needs replaced. There's no other way to fix it.
The hesitation/stumble can also be caused by the weight/check ball getting gummed up. This usually occurs when the carb has been left sitting with fuel in it.

boyee

iTrader: (3)

i know i havent posted here in a while and im not meaning to thread hijack but i just wanted to contribute here instead of making a new thread and for another point of view about the stumbling/hesitation.

i just had these symptoms happen to me for a while now but ive been too lazy to investigate and fix it. it stumbled a little around december and would get worse if i drove hard. if i drove the car easy it would be fine. yesterday my car had serious troubles idling and running smoothly and would eventually die. this morning it took $5 and 10 minutes to put in a new fuel filter and now idle is very smooth as well as acceleration.

RotaryMelon

iTrader: (7)

I have the same problem, when I press the gas hard, it seems to almost stall before the rev comes..

Is there a detailed procedure for replacing the accel pump at home? or does it require rebuilt of carb.. (dont know much about carbs)

mazdaverx713b

iTrader: (91)

this sounds like the gremlin that i may be dealing with.... i should pull the carb and change the diaphram and gasket. any tips for changing the diaphram?

Bigmotoxer

Yeah I think you can change it w/the carb still on the car if you think that the accel pump is the culprit.
There's the c-clip that holds the accel-linkage pin, then the pin itself, watchout for the 2 shims as you pull the pin(I've found the most valuable tool for me has been my retractable/extendable anntenna w/the little earth magnet on the end,) four small phillips screws and you're in.

Bigmotoxer

BTW, I only comment because I just spent 2-3 weeks playing w/this carb over and over until I feel like I could rebuild it in the dark, Now if I could just figure out the omp I'll be on my way

mazdaverx713b

iTrader: (91)

thanks for the advice!! i'm just at wits end with this carb. i pulled the air horn off and cleaned out the float bowles, the air bleeds, installed new needles(the seats were too tight to remove and i didnt want to damage them or the carb), and blew through every air bleed while the air bleeds were still attatched. the engine ran better for a couple of days and now i'm back to this bucking at half throttle, and almost stalling under load. i can sit there in neutral and rev the **** out of the engine with no problems. but as soon as i give her some gas and let out that clutch, its bog time.

Bigmotoxer

Yep that's what mine was doing...I rebuilt my carb completely(4 times until I got it right,lol...seems that I put a gasket on upside down(and it does matter), then had to set my float adjustment(this is very important), then once blew a ball and weight out in the yard(they're so darn small), once the top gasket wasn't sealing because I didn't tighten the center bolt,lol and I never said this before but I remember putting the accel pump in backwards too,lol(I probably shouldn't have told anyone that)...now all I have to do is to learn to master the air/fuel and idle/speed adjustments( I'm a dirtbike carb master but the nikki kicked my ***).
I would say try the accel pump first(you can order a basic rebuild kit for $20 from Black Dragon), if that doesn't do it pull the carb and replace seats(changing needles is good but seats are important too(I know I had to use vice-grips to get my old seats out), remove all jets one at a time and spray carb cleaner through them(put that one back before removing another if you're not real familiar where they all go)and clean the places that the jets are removed from, set the float heights w/the paper guage they send you(floats should only drop down under their own weight 2" to the lowest point and w/the top plate turned over should only go up w/in 5/8" to the top plate...check these measurements w/gasket on), watch the direction of your gaskets, don't loose the ball and weight under the brass center squirter screw(looks like this "+" looking down at carb) or the ball and weight under the brass flathead screw under the top plate of the carb just above the accel pump, snug the screws on the top plate, torque the center bolt then tighten the screws.
I love looking in that window and seeing my fuel level right on the line, I also like NOT seeing fuel flowing into my darn carb when the fuel pump is on and car is off.

mazdaverx713b

iTrader: (91)

thank you for the tips on the carb. i've had a lot of rx-7's(15) and this one in particular has given me a great deal of trouble. even though it frustrates me, i love it. the accomplishment factor of when things are fixed greatly outweigh the trouble of fixing it. i didnt have a chance to get to the car today, as i spent the day with my wife organizing the baby's room and getting things prepared for her arrival. i'm going to pull the carb tomorrow evening and go for round two. hopefully after cleaning the jets and replacing the accelerator pump diaphram and gasket my problem will be solved.

Bigmotoxer

yeah I seen that you had 4,000 post so I knew you knew what's up but I was glad to share my tips on what I learned(mostly from my own mistakes,lol) and my carb seemed to have the same symtoms so anyway. Keep us updated, curious to know what it is...
You know I thought about it after I posted...I thought "I'm explaining float heights to mazdaverx w/4000 posts and 15 all-time owning RX7 champion"...well I thought something like that goodluck

mazdaverx713b

iTrader: (91)

being that i have 4K posts and have had 15 7's, i still don't know it all. i do understand float height and how to measure, as i had to do this when replacing each needle. however, i'm glad you posted that because if someone ever needs help and searches and comes upon this thread, they may find exactly what they're looking for based on what you posted. i am going to try and get everyting done today, however its supposed to be kinda crappy out, like 43 and rainy. i'm working pretty much most of the day(i'm a police officer and the hours are pretty long). i'm just going to replace the acc pump diaphram and gasket, clean the jets, and reconnect the bimetal choke linkage(it came loose and flopped all crazy like and i have to replace the cotter pin). i'll go from there and let you know what happens.

Kentetsu

Sounds like a clogged jet to me...

mazdaverx713b

iTrader: (91)

well, one jet was clogged. i pulled them each one at a time and cleaned them. i then replaced the accelerator pump diaphram and gasket(which was built right onto the new diaphram), and recleaned the air bleeds and passages, the float bowles, and finally the floats. all is fine now. i finally have a very good running 7!!!! well, other than my 1980 Leather Sport. thank you all for your help and suggestions!! very much appreciated!

Bigmotoxer

yeah the accel pump is one piece, it is it's own gasket guess what I did today? I pulled my dang carb again...went through it again thoroughly and found that there was a piece of crap stuck in the main primary jet(that's why it wouldn't run unless I kept rapidly pumping the pedal, how it got there I have no idea because this carb was spotless when I reassembled it...I guess it was in there somewhere and just floated around and got lodged in the jet, feels good to have it running again!...doesn't it?

mazdaverx713b

iTrader: (91)

well, this is the first time the car has been running well. i can say that i'm very pleased and i really like the car! it feels GREAT! i had some small pieces of sediment in my front primary jet that was just awful and a blockage in the rear primary air bleed. i dont know how i overlooked those the first time. glad to hear that you got your car back on the road! sometimes i think that some particles may get by the fuel filter and clog up the carb. it just makes sense to me.

Bigmotoxer

yeah as wullf suggested I'm gonna put dual fuel filters on mine very soon...can't hurt.
Later

Rogue_Wulff

Usually, it's a case of crud accumulating inside the lines, between the filter and carb. They break loose over time, and get into the carb.
Adding an extra filter, right before the carb, will prevent this stuff from entering the carb.

mazdaverx713b

iTrader: (91)

thanks for the tip. i think i may add the second filter. i guess its something thats commonly overlooked as a prevenative measure.

trochoid

iTrader: (6)

It's not something one would expect, but after tearing down more than a few stock carbs and seeing how much crap is in the screens inside the carbs, a pre-carb filter is becoming one of my standard mods.

mazdaverx713b

iTrader: (91)

i'll have to agree with you that there was a TON of crap in the screens and the bowls. even the float had what appeared to be rust stuck to the side of it. i'm putting my second inline filter in this weekend. i'm going to install a clear filtr so that i will be able to see if i'm getting any particles after the first filter.