Repair-It

The Mazda is having an intermittent problem where it almost has a hard start. Mostly in the morning. Seems like first start of the day. At first I thought it might be because the AC was on, and it was having a hard time like the starter was going. I have done some research and it seems that it could also be a low fuel pressure thing, where the engine doesn't get enough fuel until the pump runs for a few seconds causing what seems like a rough start. Others have said a low battery, although I think this is unlikely but easily testable. Weird thing happened yesterday, as I was starting it the starter sounded like it was being energized while the motor was running. That happened on and off for a second. The car then was fine after that. The car has never not started. It is just a hard couple seconds, sometimes a shake or stutter.


Potential fixes listed:
New battery - Will test today but I think it is fine.
Spark Plugs - About 5 bucks each for Iridium. Pretty sure that is what I used at around 80K miles. At 135K now.
New Fuel Pump - $78 - 494
New Fuel Filter - Not on RockAuto?
New Starter - $88 - 150 after core charge
New Fuel Pressure Sensor - $175

Someone posted this:
https://www.mazda3club.com/mazda-servic ... ems-55478/

1. Check fuel hold pressure after turning the engine OFF for 5 minutes or longer. Refer to Workshop Manual (section 01-14 FUEL LINE PRESSURE INSPECTION). Specification is 36.2 psi or more.
If below specification, check fuel line for clogging. If fuel line is clear, replace fuel pump according to Workshop Manual (section 01-14 FUEL PUMP UNIT REMOVAL/INSTALLATION).
If fuel hold pressure is okay, check spark plugs for fouling.
If fouled, replace spark plugs with modified plugs.
If not fouled, perform normal diagnostics according to Workshop Manual (section 01-03 NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK).
2. Verify repair.

My generic advice would be to test for fuel pressure bleed down overnight (or start with 5-10 minutes if it is really bad, and you'll see right away). If it does, my guess would be fuel pump based on my experience. My truck has this issue intermittently and letting it prime the fuel pump (key on, off, on, off several times) seems to help, which proves it is a fuel pressure bleed down problem. I think the Ranger was also doing this intermittently before I sold it.

My Caprice, being a low pressure system, is designed to bleed down so the fuel pump check valve doesn't matter as much. But yeah, what's likely happening is the check valve in the fuel pump is letting all the fuel in the inlet line back to the tank. You could try the key on for 3 or 4 seconds, key off, key on, etc., and see if that helps, if the issue is repeatable enough. That should ensure the fuel rail has a good prime (and can verify via test gauge, which I have).

Never a bad idea to do the fuel filter.

Check and see if you have a conventional or returnless fuel system. If conventional then your fuel pressure regulator could also be bleeding pressure back to the tank via the return line. If returnless, it can pretty much only be the pump, other than a fuel system leak (which you would smell).

Quick online look sounds like it is returnless. There is no fuel pressure regulator option on rockauto. The fuel filter wasn't there either which I have seen in youtube videos so rockauto is obviously not automatically a fully inclusive list. Where do you guys get your field Service Manuals?

For the factory paper manuals, I've always gotten them from these guys:
http://www.helminc.com/helm/welcome_sel ... Style=helm

But it looks like they don't do Mazda (but they do Ford). I don't know who would make the Mazda one and it seems very strange that they would use a completely different company for what is basically the same car as a Ford Focus.

Also wouldn't hurt to have a manual like a Chilton or Haynes, which can often provide simpler instructions and sometimes time savers vs the factory method.

bill25 wrote:Quick online look sounds like it is returnless. There is no fuel pressure regulator option on rockauto.

You have a regulator somewhere. It could be at the rail (just before), at the fuel filter, or even at the pump in the tank (possibly integrated to the fuel pump). Which would lead back to requiring pump replacement. Assuming it is the pump, you aren't really hurting anything by delaying the repair, except for some extra cranking. And you could potentially get around that by priming it before crank.

The problem isn't easily repeatable.

And you could potentially get around that by priming it before crank.

I am going to try this consistently for a few days to see if it helps. I think the tank has to be dropped to change the pump which sounds like a better job for the spring...

I am going to check if the fuel filter is near the rear wheel well. If it has one, which is debated online... If it does, it looks easy to change based on a youtube video:

https://www.youtube.com/watch?v=mPlz-5S ... MeAx9egXsf

I might do this soon if I find it.

See if you can find a fuel pressure test port.

bill25 wrote:Where do you guys get your field Service Manuals?

eBay

I found one. This is one of the cheaper ones. I didn't realize these were so expensive.

https://www.ebay.com/itm/Original-2009- ... SwutpZlHFu

I might order this to start:
https://www.amazon.com/Haynes-Repair-Ma ... da+Mazda+3

I understand that this will probably not have the same level of detail. If my car were more interesting I would probably want the Shop Service Manual.

Helm wants $200 for an 09 STS/V.

Good thing I bought a whole electronic system (GM) for $20, 6 years ago (runs in a VM and OS/2 Warp is involved somehow...yup). That's how I've been posting PDFs for Adam. It also has TSB and recall info/procedures. I don't think it goes back to my 93 Caprice but I have the book for that. Haven't actually looked up the Roadmaster...but I am covered for the 3 Cadillacs which is where I'd really need the FSM anyway.