JonnyOThan

First off, I'm pretty new to rotaries - I understand the basics, but I have next to no experience, so I apologize for my newbishness.

It's a 1984 with the 12A engine.

As the title says, the fuel pump doesn't run when I turn the key to the 'on' position. The car cranks, I replaced all spark plugs recently, but it doesn't start. It's been sitting for maybe 2-3 years without running. I've drained and replaced the gas but not oil. After I stop cranking the car, I can hear the fuel pump running.

Do I need a new fuel pump or something related to it, or should I look more into compression problems, since spark and fuel seem to be present?

bouis

The fuel pump will only run when the engine is turning over. If you think it's fuel delivery, pour a tiny bit of gas down the little barrels of the carburetor.

wae

You're observing normal behaviour, at least in terms of the fuel pump. For reasons that escape me, Mazda decided to run the fuel pump only while the engine is cranking, not just when the ignition switch is in the "run" position.

You might check the fuel filter to be sure it's clear of any murkiness, if you're having a fuel delivery problem. The first place I'd look, though, would be at the top of the thread list. You'll find a "sticky" thread there that has the word "FAQ" in it. There's plenty of information out there to the tune of "car sat for umpteen million years and won't start now".

JonnyOThan

Hmm...My Haynes manual says the fuel pump should click when the ignition is turned on - did they mean 'start'?

I'll check the filter next, I suppose. Thanks.

Oh, side question - the manual also said you couldn't use standard compression testing equipment with the RX-7, but I saw another post that mentioned using a compression gauge. Should I just take the plugs out and use the "sound" method, or is there special equipment I'd need to check it?

Jeff20B

iTrader: (13)

Yet another '84-'85 fuel pump weirdness thread. Sorry, I couldn't resist.

mar3

iTrader: (8)

It will come on just for a second and then stop. This behavior is specific to only the '84/'85 years of the 1stgen RX-7. A fuel kill relay under the dash wants to "see" the engine physically cranking over before it will allow power to pass to the fuel pump. Do a search for "fuel" and "cutoff" or "bypass" and find V8kilr or '79+'80+'84_rx7' threads on how to bypass the fuel kill relay...

wae

If you look in the 13th chapter of the Haynes book, around section 6 or so, you'll find the necessary instructions to jumper the fuel pump cut relay. You're looking for figure 13.16.

In my opinion, that's the most irritating thing about pretty much every Haynes book that has been printed. The book covers, in great detail, the very first year of the generation of the car. In the last chapter they gloss over any "changes" that may have been made. So, instead of having a section of 12As and 13Bs, we get a huge discussion about 1979 12As and thermal reactors, but just a fleeting whisper in regards to 13Bs, cats, or any of the changes they made to the 12A over the years (not many, to be sure, but still...). Get yourself the FSM for the year of your car. Even the ones that are on-line in PDF format are better than the Haynes book -- the pictures aren't always 100% clear, but at least when you read something in that one, you know it's going to apply to the car you have in your garage. (For the most part).

As far as the compression test: You're not going to be able to get worthwhile numbers from a boinger compression tester. However, if you hold open the valve, you should get three "bounces" per rotor. Each of those bounces should be about the same. Any bounce of the needle that is significantly lower than the rest would indicate a failure in an apex seal. It's my personal beleif that watching the needle is somewhat more accurate than listening for airflow out of the plug holes. Sounds tend to be a little deceptive when you've got your head next to the block, but watching that needle is more precise. Unfortunately, you won't be able to take the readings from the compresson tester and compare them to the specs published by Mazda, but ou'll at least be able to deduce the presence of a problem.

JonnyOThan

Ok, thanks for all your help! I'd heard of pouring gas in the carb, but I tried starter fluid before and that didn't work very well. Maybe I just had to get the last few drops of old gas out of the tank.

I took out the leading plugs one at a time, seems to be getting 3 equal pops (not really a pop, but that's the closest word I can think of) from each.

And...no more need for this thread.

peejay

Hmm, mine doesn't. It only comes on when cranking or when the engine is running. Simply cycling the key to "run" won't engage the fuel pump even for a second, a fact I discovered (to my great annoyance) after I replaced the fuel pump and it took forever to prime itself. Had to crank the engine *forever* since I was too lazy to jumper the relay.