Mazda 626 - Fuel Pump Removal & Fuel Tank Cleaning

Part 3 covers fuel pump removal from the fuel tank and cleaning the fuel tank of sediment.

[@fabian_barrios_fabian]

My car is a 1997 MX6, because the floating bulb that measures the fuel level is separate, in another part than the pump?

[@CATownsend777]

Need some scary music for that green slime...

[@CATownsend777]

Algiers won't grow in gas

[@DJDevon3]

The fuel pump doesn't click. Maybe you meant the relay? That relay will click ONCE when the car is turned on. Injectors are a heavy duty solenoid. They click when they spraying fuel each time the spark plug fires. Maybe 200-300 beats per minute (just a guess). If you put your ear to them with a long screwdriver acting as a stethoscope you will hear them click. You have to be real close to hear them they are pretty quiet. It almost sounds like a fast ticking noise.

[@CATownsend777]

What a stupid design

[@dad0041]

Was that a penetrating spray that you used at the 1:44 mark? Also, what was that tool that you used at the 1:49 mark to pull the hoses?

[@DJDevon3]

1:44 Ummm PB blaster which was definitely the wrong stuff to use. Should have used silicone based lube not petrolum based lube. I was in a hurry, definitely not the stuff you want to use, I set a bad example there. :P 1:49 are 90 degree pliers, very helpful for getting at hard to reach areas. It's better to have one and not need it then need it and not have one.

[@DJDevon3]

If you don't hear clicking on any injectors then they aren't firing... probably because they aren't getting power or as you mentioned, the main relay (not fuse) isn't sending voltage to the injectors. Could be a bad ground too. Injectors will attempt to fire if there is fuel actually in the line or not as long as they are getting power.

[@DJDevon3]

You can try to replace the main relay but I'm against throwing parts at the problem. I would much rather you listen for the injectors firing before putting money into a relay. Name of the game is diagnostics here... it will save you money.

[@DJDevon3]

Remove the top of the filter box and spray a little starting fluid like throttle body spray into the MAF. Let that get sucked down the intake as a fuel source. I have a playlist called "Fuel Series" for testing fuel pressure. I neglected to mention the main relay in all of the videos! Yes the main relay is what provides power to your fuel injectors. One easy way to check injector firing is turn the engine over, use a long screw driver against an injector and listen for the rapid clicking.

[@DJDevon3]

"So, if their not clicking/injecting fuel into the chambers, what would be the likely reason?" Then it could be a bad main relay, injector harness ground, or cam position sensor. If your injectors aren't firing then test the relay. ;) Honestly this should have been asked on Mazda626.net because this Q&A stuff doesn't work so well in KZbin comments.

[@youreawalkingdeadanddoknow3245]

I forgot to mention its a 2004 Mazda MPV. Also wanted to mention that we did do a wire and sensor cleaning on every sensor on the drivers side of the engine, if thats relative to the PCM's issue in any way you could think of. I think because the guy that did it didn't disconnect the terminals and possibly leaving the key in the on position as he was cleaning and then connecting, he might have, no I'm certain he shorted out the PCM, but I'm hoping you know of a fail safe to it that would prevent that? I'm replacing both anyways, what would a flashing cause should I need one from the dealer or car electrical shop?

[@sherp2u1]

I thought the clicking was supposed to be from the fuel pump? So the clicking is supposed to come from the injectors? Would I be better advised to replace the main relay then first? The fuel pump replacement is obviously way more work, and not completely sure its jacked up, either? Thanks for you advice, really appreciate it!

[@sherp2u1]

So, if their not clicking/injecting fuel into the chambers, what would be the likely reason? I am trying not to throw parts, but, a good diagnosis is almost impossible to get here...Not enough money in the job, for most mechanics, but the car was a solid performer up to this!

[@sherp2u1]

DJ, I am about to replace the fuel-pump on a 1995 Mazda 626, European Specs...Should I change the main-engine relay first? Or would that not cause the no start? I am geeting spark, but, no smell of fuel from the cylinders after I take out a the spark-plugs!

[@sherp2u1]

Ok, thanks a lot for all your help! I didn't know of a Mazda 626 net, I will definitely look it up now!

[@youreawalkingdeadanddoknow3245]

Hello, got a problem, hoping you can pin point for me? Ignition turned on, fuel pump doesn't make that usual on cranking noise, seems dead; popped line, ig on, no fuel pumping? Also when I connect my reader, the PCM shows up as "Cannot connect"? All the fuses and relays are okay to the fuel pump, can't say whats with the PCM's doing?. All sensors are working, and plugs are firing, sprayed a little :Ether"on the intake and it tried to start? Fuel pump for sure? Whats with the PCM, why is it not connecting with my Code reader? Should I change that too?

[@DJDevon3]

+Don Smi Put 12v to the fuel pump to test a fuel pump. Bench test it.

[@youreawalkingdeadanddoknow3245]

+DJDevon3 Found the problem, wire harness came loose and burnt on the manifold cover. After that I found that the fuse box is categorized wrong.Fuses for what they said they were for , just was totally flipped. Things that were said to be on the right of the panel were actually on the left? Unique? It would be my luck. All in all its been a mission, Thank you.

[@DJDevon3]

Don Smi Having things backwards in the fuse box is not good. Entire wiring harness should be visually inspected now. Continuity and short circuit testing. Unless it's the wrong fuse box lid diagram for your year. I've seen people lose fuse box lids and replace them with ones from different years that have different diagrams, something to keep in mind.

[@youreawalkingdeadanddoknow3245]

+DJDevon3 I'm thinking you're right on the cover belonging to another year or something, the thing is I bought the car from a dealer used with only 29K miles on it. The circuitry testings been done and all's well this far. She fires up nicely, so I'm thinking as you've suggested, it has to be the cover. Thanks Buddy. If you ever need any Big Rig advice, let me know? Thanks.

[@DJDevon3]

Don Smi You can confirm it by looking up the body electrical troubleshooting manual for the specific year of your vehicle on pmx626.info. It's a free resource so not all years are available. Fusebox diagrams are in the body electrical troubleshooting manuals not the workshop manual.

[@danellsworth5872]

is this the same for a 88 626

[@DJDevon3]

Pretty much the same procedure for any vehicle but to be sure please reference the WSM.