Car starts then engine shuts down

[andyd]

I would rig a fuel pressure gauge. I would look under the distributor cap for anything amiss. I would clean the dust off the cap's inside and make sure the rotor is intact. I would jump power to the pump at the relay for a static test. What do the plugs look like Is where I would begin, then the cap inspection, then then pressure check. IAC sticking open? This is all things I check on the 528e, no experiences with 626, Good luck. please report your fix when it happens.

 

[tbm3fan]

Everything was new in the ignition system from plugs, to rotor, to cap, to wires on Sunday four days before...

 

[HangFire]

Originally Posted By: tbm3fan
Everything was new in the ignition system from plugs, to rotor, to cap, to wires on Sunday four days before...


Last changed, first suspected. Start putting old parts back on (if you still have them) until the problem goes away.

 

[Tosh]

Originally Posted By: Pontual
Fuel pump relsy or Tfi hall effect.

If it were a Honda I would think fuel pump (or 'main') relay.

 

[tbm3fan]

Well as we know you need spark, air, compression and fuel. I know spark is there as the engine has run. There is also air and compression for sure. I was never completely sure about fuel.

This morning the car started briefly for 1-2 seconds and that was it. It will no longer start even though it turns over fine. With spark still there that means fuel is the issue more likely than not. Will order a fuel pump and see what happens. Possibly a slow failure rather than a sudden one.

 

[Colt45ws]

Can you put a gauge on the fuel rail and see if it has pressure?
If you have a cheapie air gauge it will work for a one time thing, though I would throw it out afterwards.

 

[mk378]

Now that it doesn't start at all, it gets a lot easier to test stuff.

Quit just buying parts that's expensive and the hallmark of a lousy mechanic.

At least check for flow at the return line before saying there must be a fuel problem.

The vane airflow meters have a switch that turns the fuel pump on when the vane moves off of zero. You can test that by removing air cleaner and gently pushing it open with your finger.

Any airflow controlled engine will start poorly if at all if there is an air leak after the meter.

You should check with a timing light to confirm that cylinder 1 fires at or near TDC every time. Failure of a timing related sensor seems likely.

 

[Pontual]

Once that happened to me! In my V6 Vulcan, I ended up changing the wires, misplaced, 2 of the 3 cylinders of the rear bank. I burnt my cataliser that way, by trying to run an engine with 2 cylinders spiting raw fuel on the exhaust manifold. You need to recheck distributor cap to cylinder wiring sequency.

 

[tbm3fan]

My decision is based on an educated guess and past experience. There have been two 626 cars in the past where their pumps went out at 17 and 18 years. This is now 25 years old. Remember the car was driving down the freeway and the engine stopped quietly. I checked on my other 626 and can start the car with the air fuel meter disconnected for a bit. The ignition system is in perfectly as is the timing and the belt.

Now these cars, from this generation, do have some known issues with their fuel pumps and ignition switch. It would be nice to have a pressure gauge, and will most likely get one, but it won't be till this weekend. If it is the pump then I would need to wait another weekend to get it so I'll just get the correct Densco from Rockauto. Having a spare is no big deal. You all should see my garage shelves with spares from my rebuilt carbs, to my rebuilt distributors, to heads, intakes, exhaust, belts, hoses, hardware and so forth. With nine cars one needs stock.

 

[Vikas]

Making an assumption here but swapping the fuel pump will involve disconnecting electrical connection, input line and output line. If you were to remove the output line first and put in a glass jar, you would know 100% if the fuel pump is working or not. So why not test it before swapping?

Educated blind swapping is OK on some parts where swap is trivial and the cost is low but in this case, testing is easier than swap so it should be done first.

You can also take the approach that the fuel pump is old and it will be replaced regardless.

 

[tbm3fan]

Whole thing is moot at the moment. My wife filled the gas tank up that morning and consequently I cannot take the lines off the top of the housing holding the pump. As soon as I moved one line partially off fuel sprayed out into the rear seat area. Pushed that back on quickly. Tank has no drain plug and for some reason it is impossible to siphon any gas out the filler tube. Hose goes in almost 3 feet and then stops short of actual gas.

 

[Merkava_4]

Originally Posted By: tbm3fan
As soon as I moved one line partially off fuel sprayed out into the rear seat area. Pushed that back on quickly.


You're supposed to bleed off the line pressure at the fuel pressure regulator before doing that.

 

[TFB1]

Originally Posted By: Merkava_4
Originally Posted By: tbm3fan
As soon as I moved one line partially off fuel sprayed out into the rear seat area. Pushed that back on quickly.


You're supposed to bleed off the line pressure at the fuel pressure regulator before doing that.


This^^^

But if it has enough pressure reserve to make a good spray the pump probably isn't your problem, seen engines run(at least idle) with only 1/3 of normal pressure...

 

[tbm3fan]

Originally Posted By: Merkava_4
Originally Posted By: tbm3fan
As soon as I moved one line partially off fuel sprayed out into the rear seat area. Pushed that back on quickly.


You're supposed to bleed off the line pressure at the fuel pressure regulator before doing that.


Time to pick this back up. As for the fuel the tank was 100% full the night before. The access opening is slanted which puts the lower edge about 3/4" lower than the top edge. Manual calls for getting gas out before attempting to open up.

Anyway while I was now waiting to get back to the car, due to rain, I went to start it again for the heck of it. This time not even a catch. Finally got my wife out to start the car while I pulled the coil wire and found no spark now.

Ok, that now means something electrical failed. More rain but eventually pulled out my multimeter. There was 12V from the ignition to coil positive. In fact all terminals had either 12V or 6V as per the factory manual which I was able to buy. Coil passed resistance tests. Since I have a another 626 I swapped coils and confirmed my coil was fine. So ignition switch, wiring and coil were fine.

Next thing up in the cars simply ignition system was the distributor pick up and ignitor. There was 12V to the ignitor from coil negative. However there was also a constant 12V out from the ignitor when cranking which was wrong plus failing resistance tests.The internal switch was not opening and closing. A new ignitor was $119 locally and $80 from Rock Auto while a rebuilt distributor was $75 from Cardone. Opted for the rebuilt which happened to have Made in USA ignitor and pick up. Once in the car started immediately. With that the fuel pump went onto my shelf holding spare Mazda parts.

Getting my hands on a very large 6" thick 1990 factory manual was helpful. Mazda does a really good job in how to troubleshoot all their systems.