Hey hey hey, so my 1990 gtu is having a problem with the fuel pump. The most retarded thing is that it seems like it used to work. Here's the problem

A week ago or so, we had it to the point where we could start the car by spraying starting fluid into the intake, and then holding the air flow meter in just a bit, not too much not too little, and the car would idle for as long as we held it. so obviously either the engine is not getting enough fuel or the afm is off... So, we depressurized the fuel system, and i put on a new fuel filter (the old one was heeaavy compared to the new one!), and reconnected the wires, tried priming the fuel system, but now the fuel pump isn't pumping at all. i reconnected everything i had disconnected, but the fuel pump seems like it's not even getting power now, where it had to have been before, because it would idle when holding the afm in, but now it doesn't.

any ideas?

 

Check the fuel pump relay under the dash, make sure it's picking

 

that seems to be working, and everything else is working and connected. i don't understand how the pump was pumping like a week ago, and after disconnecting and reconnecting it, it's not. any other ideas? i want to get this car on the road.

 

and what exactly do you mean by picking?
i checked the fuel pump relay which is up by the air intake, not under the dash...there is none under the dash.

 

The elec path is shown in the attached jpg. The location of the items in that jpg are on the next page in the wiring diagrams for the series five cars which is downloadable from this site in the FAQ thread.

 

Did you by chance hook the fuel lines up backwards?

Did you remove the incoming fuel line and ensure your getting flow from the tank?

Did you hook up the fuel filter backwards?

Have you checked the under hood fuses? Have you checked any fuses yet?

I seen you checked the relay, but not the fuses?

Have you swapped the pump out for a known working one? Thats what I would do, if all lines are correctly connected and all relays and fuses are 100% perfect.

Did someone else help you with this? Maybe they did something you wasn't aware of and this is causing your problems.

Why were you messing with the pump anyways? what was the original problem? It never ran??

 

well, as i said before, to answer your last question, the engine wasn't getting enough gas, but it was getting some gas, and by pushing in the afm (giving it more gas) it would idle, but never went more than idling. so i replaced the fuel filter because that may have been the reason it wasn't getting enough gas. i depressurized the fuel system so i wouldn't get gas all over my face when replacing the fuel filter, and after installing it and reconnecting the fuel pump, the pump wouldn't pump at all. it obviously did before, because the car would idle, but just not enough. now it doesn't

i checked the fuses, but none were labelled fuel pump or fuel anything, so i didn't know which one it was.

and i checked to make sure i put everything back on the right way.

the fuel filter i put in was brand new, and even if i bought a faulty one, it wouldn't matter because the fuel pump is not pumping...i checked the line before the fuel filter to check, and nothing was coming out.

so idk.
kinda sounds like a fuse problem. but i don't know which one goes to the fuel pump...

 

Does anyone know where the fuse for the fuel pump is located on an s5?

 

Factory Service Manual: http://pdftown.com/PDF-Mazda-RX7-1989-1991-FSM.html
Password: pdftown.com

run through the fuel system part. it mentions a plug near the drivers fender you can short to get the fuel pump to come on.

take both fuel lines off. jump the wire and see if fuel comes out. if not then hit up the electrical section and find the hot wire (+) to the pump under the access panel in the rear.

a test light ($10 or so at a parts store) will be needed for the next step.

pop open the panel and clip the light to a good ground. poke the light far enough into the hot wire to get a connection but not far enough to go through. jump the connection again. if the light turns on and fuel doesnt come out then the pump is bad.

if the light doesnt come on then you need to find the relay and make sure you can feel it click when you jump the connection. if it clicks then you need to go through the book and find the fuse location in the electrical or fuel section.

 

It's the ENGINE fuse in the interior and since you have read the FAQ thread you KNOW where in that thread is shown the fuse box cover.

Well gosh and golly, I seem to have shown the fuse in post #5 so this post is redundant.