Adventurer

My '85 GS with 212K miles suddenly quit without warning yesterday. This car is new to me - I've owned it about a week. Driving along at about 30 MPH the thing suddenly sputtered and died. Battery strong. Cranks good. No start.

I suspect fuel filter or fuel pump. Where are they located? Is there a fuse protecting the wiring to the fuel pump? Could be that too.

This car is a 1985 model with a carburetor. Is there a computer for me to worry about?

Final question: Are these RX-7's really this tempermental? This was supposed to be a car for my wife to drive. I can't see putting her in a car that is prone to crap out without warning.

Lookieme

Um... I didn't think a 12A would do that kind of thing. I can expect it out of an 85 SE with a 13B...

Adventurer

The previous owner tells me that this engine is a replacement, so I'm not sure (and neither is he) what exactly was put in there. It clearly has a carburetor, but it also has six short tubes next to six color-coded electrical connectors that look like they might be fuel injector related.

Lookieme

Hmm... I'm not qualified to say anything more, and I don't want to get flamed for talking out of my ***... I'll let one of the more experienced guys comment on this...


Where at in TX are you? I'm in Dayton, outside of Houston.

Adventurer

At the moment we are in Riverside CA, but our home is in Livingston TX.

cjf

iTrader: (1)

oh boy, it could be anything...too hard to diagnois like this...but with 212 miles, it scares me...hope you did not pay to much for it with that kinda miles!!.... you never know what kinda engine you have in there either..(junk yard or even an engine that was on its last leg anyway)....I don;t think I can help you as it could be anything...hope your engine just died...that is how they die by the way ( not all the time but a lot of the time) ..you simply loose compression and that is it....Good luck...cjf

anthrax

Thoes tubes and coloured molex connectors are part of the emissoins system. Take a look at the rotor housing just in fornt (I beleave) of the Oil fill tube and read the engin code will say MAZDA 12A or MAZDA 13B. That will hopefuly give the xp's a bit more info to help you out.

I have found they are much more reliable then my bonger (****-ton) pwered winter car . So please don't let this intial exsperience get you down. They are a GREAT car.

But as for what is wrong I have no idea

Best of luck

anthrax

Jeff20B

iTrader: (13)

Ignitor?

WackyRotary

Main engine fuse? Pulling it or it burning out will cause the engine to die instantly.

AdrenalifeRX7

Turn the key to the on position. If you hear the fuel pump whirring behind you then it's most likely still functional. That clump of wiring is what nicknamed "the rat's nest" It's entirely emissions/vacuum related. The first thing you should do is check for the fuel pump noise, if that's good then check for spark. If there's spark then you should pull a main fuel line to the carb and have the wife crank the motor and see if it's getting an ample amount of fuel.

WackyRotary

I guess I should of mentioned I was refering to a SE. 12a won't die suddenly if the fuse is pulled because the fuel slowly gets sucked out into the engine.

I don't recall but does the SE work like the '84-85 model were the relay only works when cranking and when its running? There is a jumper wire in the engine bay that you can connect the termials to test the fuel pump when the engine is in the on position, I think its a green one.

MIKE-P-28

iTrader: (1)

@212k Id imagine its gonna be prone to a lot of things, not to mention its 18 years old....Its an old car for crying out loud Its gonna do **** like this all of the time.

Yes theres a fuse for the fuel pump, but id be checking the one in the fuse box thats labeled engine, its a 20a and it operates a multitude of things under the hood including the ignition system.

Have you done a compression check lately?

Rx7carl

NOT! 84-85 cars will not allow the fuel pump to operate in the key on position. Only when cranking, and when in the on position with the engine running. The emissions computer controls this function through a relay under the dash by the steering column.

Adventurer

To answer someone's question above, yes it is a 12A engine.

I turned the ignition to ON and listened for fuel pump sound, but there was none.

I bought the Haynes manual. It does not distinguish between different years as to whether or not the fuel pump should be running with the ignition ON. The wiring diagram in Haynes shows the fuel pump being powered directly off the ignition switch with no relay in between.

In a different thread on this forum I read about a yellow connector under the hood near the spark tower that will temporarily power the fuel pump for testing purposes. I could not find any such yellow connector under my hood. Haynes does not mention such a connector either.

Checking all the fuses is my next move

AdrenalifeRX7

My bad! Well he said it was a 12A so I figured...

MIKE-P-28

iTrader: (1)

84-85, fuel pump only runs while cranking.

The check connector isnt on a 12A only 13b

justrx8

TAKE THE FUEL HOSE AT CARB. OFF HAVE SOMEONE CRANK IT IF FUEL COMES OUT IT WORKING . REPLACE THE FUEL FILTER . I HAD THE SAME PROBLEM LAST I REPLACE IT . IT UNDER THE LEFT REAR BEHIDE AXLE IT WHITE IN COLOR IT COST ME $5.OO . I WENT ON THE EXPRESS WAY RUN IT ABOUT 100MPH HAD TO SLOW DOWN ALMOST GOT BUSTED BY THE STATE POLICE LOL

Suparslinc

my fuel pump runs with the key on, but I think I wired it that way.

Glad to see you have crank, at least the engine isn't seized. Is it running now?

Keaponlaffen

Just having fuel come out of the line isn't enough. It has to be the right AMOUNT of fuel. I had what I thought was enough fuel coming out of the line, but when I did the test in the Hayne's manual (something like it has to pump 1100ml's of fuel in a minute), it failed... only had abotu 450ml's...

By the way... the caps lock key is located to the right of the 'A' key on your keyboard. Pressing it once right now will enable you to speak in a normal voice, instead of yelling like cro-magnum man...

poweRX-7

ummmmm... well, i have an 85 gsl, and before i put my carter fuel pump in, the stock pump DID run without the engine cranking. thought you would like to know.

Lookieme

GSL, or GSL-SE?

MIKE-P-28

iTrader: (1)

everyone I ever seen, and I have seen and worked on a shitload of them it runs for a second or so, and then resumes only upon cranking the motor, it only runs for the second to estabilish some flow/presure

MIKE-P-28

iTrader: (1)

in addition early FB, and SA would clikc and the newer 84-85 would hummmm

Ultralights

90% of problems like this are either FUEL, or IGNITION

I had a distributor cap crack once and the engine stopped dead, it cranked fine, was getting fuel, pulled a plug off, and there was no spark, check the leads (with a multimeter) all good, took the cap off, and bingo, the plastic around the No1 Leading was cracked.

i would be checking, Fuel Pump, fuel filter, Ignition leads, Distributor cap, all leads to the coils, and finally test the coils. checking these things Usually fixes 90% of the problems.

I have 228,000 KM on my ORIGINAL 12A, and it still has very good compression, and i have not touched the tuning or anything under the hood in over 2 yrs. she is a very reliable girl.

when i buy any car second hand i usually replace or check the items i have listed anyway, just to make sure, you never know what the previous owner has done maintainence wise.

Adventurer

OK, it is running again. The problem turned out to be the relay that controls the fuel pump. The fuel filter was replaced first but did not solve the problem.

The Haynes manual on this car covers the years 79-85. The main section on fuel in the front of the book says the fuel pump should run with the iginition switch ON. The schematic diagram shows the fuel pump connected directly to the ignition switch ON position. As an afterthought, Haynes put in a section on "newer models" in the back. It does say that 84's and 85's have a relay that prevents the pump from running unless the engine is running. They do show a jumper location to test the fuel pump with the engine not running.