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1994 B4000 Won't Restart


mattwebb80

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I'm having an issue with a 1994 Mazda B4000 that I'm trying to get back on the road.

After sitting for a few years, I've put the following items on it:
New battery
New Fuel Pump
New Fuel Filter

I can get the truck to start.. sometimes. The reason it was parked was a few years ago you could be out driving it, stop at the post office for example and not be able to start it again for as much as an hour.

Well, we got it started yesterday. We had already flushed all the old gas and put in new. It ran for approximately 20 minutes, didn't hesitate, took the fuel and purred like a kitten. Then we tested the ability to restart it. Nada.
We took the air cleaner off and tried spraying it with a little starting fluid. Nada.

After a bit, we were able to get it started again. Again, it ran for 20+ minutes and we tried the restart test. Same results. The engine would not restart.

It would crank and act like it was trying to start on occasion, but it would never actually start.

It is throwing a CEL, but I do not have a tester and do not know what the code is yet.

We thought perhaps the Fuel Pressure Regulator had gone bad so we put a pressure gauge on it. When we turn the key on, the pressure popped up to 20psi and then slowly climbed to 38 where it stopped.
When we tried cranking it, it began to bounce back and forth between 38 and 40.
We could not get it running to test and see what the pressure was while it was running.

After some thought however, I was wondering, since we tried starting fluid, what are the changes that it is not sparking properly?

Does anyone have ANY ideas? I need to get this back on the road ASAP.

Thanks so much for your help!
 


UrbanRedneckKid

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Crankshaft position sensor...

Hard to say without knowing what code it's throwing...
 

RonD

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Coil pack should be tested, you can do it with an OHM meter
I would test it cold and then warm(no start), you can test it in the truck
Google: ford coil pack testing

I would also pull a spark plug when there is a no start situation and see if they are wet, so getting gas but not sparking.

There is also the ECT sensor, it is the "choke" for a fuel injected engine.
The ECT is a two wire sensor that tells the computer(PCM) if engine is cold or warm.
This is not the dash board temp sender, which is a 1 wire sender.

PCM runs engine rich when ECT shows cold engine, then leans it out as engine gets warmed up, if ECT always shows cold then you could be flooding engine on restart.
And this would turn on the CEL, the PCM has a timer for the ECT, if it doesn't warm up in set time the CEL comes on.
Good read here and simple OHM test to see if that's the problem.
http://oldfuelinjection.com/?p=28
 

mattwebb80

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I'll try that.

I'll be working on the truck again on Thursday.
I'm rather suspect of the CPS myself as the truck is now 19 years old and likely still has the factory sensor on it.
In any event, that CPS is getting replaced.
I'll try out the tests on the coil packs and the ECT sensors to see if they are in acceptable performance range whether we can get it restarting or not.

I appreciate your advice(s) and will let you know what I find.
 
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mattwebb80

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Ok... worked on the truck again today.
Put a new crankshaft position sensor on it. Same issue.
It started the first time, we ran it for about 15-20 seconds then shut it down to see if we could get it to restart and it would not fire back up.
We worked on it for about an hour, checked the spark, the plugs are indeed getting spark.
We checked the fuel rail again and found that things seem to be good there.
While I was fiddling with it, I found a problem with the keyswitch.
I tried starting the truck and noticed that it was cranking and I was smelling fuel like it was flooding, but when I did this I bumped the keyswitch with my hand and found that the entire keylock was rotating free of the key.
The truck won't start without the key in it, but you can grab the ears and spin them almost an entire 360 degrees.
I know the keylock tumbler mechanism where the key goes has an electrical connection in it so we partially disassembled the column and took out the keylock tumbler.
If you hold it tightly and shake it you can hear something rattling around inside the tumbler.
Could part of the mechansim that broke be shorting out some electrical signal that is causing this problem?
 

RonD

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Yes, the key switch sends power out on two separate positions.
Run is when key is on
Start is when engine is cranking

I would put a test light on an injector, one wire on any injector will have 12v when key is in Run or in Start position, see if light goes out when cranking, that would usually indicate an issue with key switch.
Do the same with the coil connector, one wire in the 4 wire connector will be the 12v line, it will have 12v when key is in run and start position, remove connector from the coil, and hook up test light see if it stays on when in Run and Start
 

tais420

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So I just went through a similar issue for almost 6 months. I replaced almost every wire and sensor on my truck along with the entire upper gasket set and still no luck.
As for you key housing freely turning issue my truck does the exact same thing 94 B4000, but for the no second start. Try this... start the truck and let it run a minute or so.Shut it off then try again if it doesn't start, which I assume it won't, then pull your fuel pump relay and try to start it again. If it starts then your problem could be your ECU is bad. I can show you a pic of one I just replaced and then repaired after I replaced it ... I work for a place that manufactures PCB's... I found THIS older thread which was the only thing close to my issue and the ground wire was not the issue he just bypassed it. The issue is actually a trace in the ECU that sends the ground signal to all your sensors.
 

mattwebb80

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ISSUE RESOLVED.

Ok, I found the problem a few weeks ago and have just been swamped with work and haven't had a chance to update this until now.

Not long after my last post, I was presented with a chance to buy a 1994 Ford Ranger with a 4.0 V6, 4SPD 4wd, extended cab, which is pretty much the exact match to my Mazda.

The Ranger was in running condition, but in rough physical shape.
It had a good motor and trans and was driveable, but had been hit in the side and was being sold for parts.
I picked it up and actually was able to drive it home.

I pulled it up side by side with my Mazda and when the weekend rolled around, we would swap any compatible sensor, wire, etc, then test the Mazda and test the Ranger.

We still could not locate the problem. FINALLY the code scanner I had ordered came in. I went and picked it up, came back and put it on the Ranger and scanned the truck. No errors detected.

I then walked over to the Mazda, put the scanner on the truck.. nada.. no codes. It wouldn't even detect the ECM was plugged in.

So, I pulled the ECM from the ranger and then from the Mazda. They had similar ECM's so I thought I'd swap them just to see if that Mazda would TRY to start a second time.

It started and actually run, albeit rough. So, I turned it off and tried it again.
Success.. and again... success. and again.. success.

I plugged the code scanner in... error code, error code, error code (because of various differences with EGR etc).

I then plugged the Mazda's computer in the Ranger.. nada.. no ECM detected.

I have since replaced the ECM in the Mazda with a factory remanufactured module and it runs like a champ.

So, ultimately, the ECM caused my problem.

Since I bought an entire parts truck to find the problem, it was, in a way expensive to find because I didn't have the scanner, however, when you consider I paid 500 bucks for the truck and got 600 dollars in new tires as well as a working engine, tranny, transfer case and differentials.. I don't think I came out on the bad end of that :)

Now, on to the next part of the project.. the slave cylinder. If I can figure out how to get the last 3 bolts off the top of the bell housing, i'll be in good shape :)

Thanks to everyone for the follow-up and advice! :yahoo:
 

RonD

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Thanks for the update :)
 

tais420

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Thanks for the update :)
^Agreed...

AS for your bolts on the bell housing try a low angle wrench or a flex ratcheting wrench <--- worked very well for me also works well to get the B**CH spark plug out.

Another tip when taking out the transmission take out the Y pipe/cat and manifold studs. If possible get some extra hands and a torch especially if its never been apart before otherwise you'll most likely break your studs and have to pull the manifolds or if your good with a torch you can sometimes melt the studs out but its very unlikely in the truck. Replace the studs with some regular socket head bolts, washers, and nuts from any hardware store, spend money if you want them to last! I cant for certain give you a size I did this 2 years ago.

Once your transmission is out trim the "TAB" ,where the cab meets the firewall, wide enough for the housing to clear it will make reinstall and future removal much easier just make sure its clean so it doesn't wreck your hands.

If you can afford it find a M05D-R1HD and a one piece drive shaft out of a newer truck you can find multiple write ups on this swap here on TRS.
 

94b2300ranger

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just to add to this, I had the same exact issues, opened up the ECM and found a burnt circuit. Soldered it back together and problem is solved.

https://imgur.com/zWta4Mw
 

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