Help! 94 929 Fires but won't start!

[929_owner]

Hey everyone, I haven't been in the forum is forever. Anyway, I'm buying a '94 HD with 98,000 miles on it. The one problem, it won't start. It fires, but just won't start. From what I'm told it died while on the road about a year ago and has sat since. When you try starting it it just cranks with a small burst every so often like it wants to fire up, but just doesn't get there.

Everything that has been checked out good so far:
fuel system pressure after the fuel pump - 60 psi I believe it was
the entire ignition system. plugs wires everything, all been changed around, even the icm and distributor, etc.
mass airflow sensor
ecu
engine compression
it has fresh gas.

Anyone have ANY ideas?!

All I can imagine now is the coolant temperature sensors and maybe the fuel pressure regulator. Thanks for any help in advance.

[JITB]

Hey everyone, I haven't been in the forum is forever. Anyway, I'm buying a '94 HD with 98,000 miles on it. The one problem, it won't start. It fires, but just won't start. From what I'm told it died while on the road about a year ago and has sat since. When you try starting it it just cranks with a small burst every so often like it wants to fire up, but just doesn't get there.

Everything that has been checked out good so far:
fuel system pressure after the fuel pump - 60 psi I believe it was
the entire ignition system. plugs wires everything, all been changed around, even the icm and distributor, etc.
mass airflow sensor
ecu
engine compression
it has fresh gas.

Anyone have ANY ideas?!

All I can imagine now is the coolant temperature sensors and maybe the fuel pressure regulator. Thanks for any help in advance.[/b]

Timing belt may have snapped? have u check it? but it sounds liek fuel, have u made sure its getting spark, pulling off the plugs, and start it, and look for spark, in each plug. And you should test the fuel pump.

[Matsuda 9]

as though it sounds unlikely it could be the belt, easiest, pull the dizzy cap and try to start, rotor spins, belt ok (does not mean it didn't jump teeth, though)

have you checked the spark? pull the plug and hold the negative electrode against earth (obviously following all safety precautions) try to start the car and see if there is spark.

have you checked the Injectors? Long screwdriver on injector - ear to the handle, turn the engine, listen for tick, no tick injector dead (rough test, better use noid light, if can spare cash) or check resistance of the injector using multi meeter.

the list of changed parts is extensive and un-necessary (esp ecu)

your issue does not seem to me to be ignition or fuel related, sounds mechanical

with all parts changed (unless some were dead) all signs point to timing belt (especially since it has cut out one day never to live again)

[929_owner]

as though it sounds unlikely it could be the belt, easiest, pull the dizzy cap and try to start, rotor spins, belt ok (does not mean it didn't jump teeth, though)

have you checked the spark? pull the plug and hold the negative electrode against earth (obviously following all safety precautions) try to start the car and see if there is spark.

have you checked the Injectors? Long screwdriver on injector - ear to the handle, turn the engine, listen for tick, no tick injector dead (rough test, better use noid light, if can spare cash) or check resistance of the injector using multi meeter.

the list of changed parts is extensive and un-necessary (esp ecu)

your issue does not seem to me to be ignition or fuel related, sounds mechanical

with all parts changed (unless some were dead) all signs point to timing belt (especially since it has cut out one day never to live again)[/b]

The belt is still intact!

Skipping teeth is a definite possibility... how can I check the timing of it??

I have checked the spark and the spark is there on all wires, and 5 of the 6 spark plugs had been changed and gapped with verified working plugs.

I have not check the injectors and am not sure how to locate them... I could use my meter on them though if I found them. What values would I need to be looking for?

The best the car can do is it'll rev around 300 rpm or whatever the starter will help it do, but not without the starter. Its like almost all the ingredients for it to run are there, but it just won't.

Has anyone considered maybe the coolant temperature sensors are dead? I'm not sure if a bad coolant temperature sensor would stop it from running in the middle of a drive though..

I also know the exhaust is not clogged.

Any other guesses, anyone?

Thanks for all the help so far.

[Matsuda 9]

i am starting to think it could be a cracked head (i always think worst :P)

the coolant sensor should not stop it from starting only from running any good. these cars (mazda in general) have a "limp home" mode that allow the car to run even if the airflow meeter has died (runs like crap and stalls if you let of gas too quick).

injectors are up the top under the manifold on the inside of the V, the manifold probably will need to come off


the manuals are here, get it VERY useful
http://www.mazda929.org/viewtopic.php?f=10&t=39

[NoD]

as though it sounds unlikely it could be the belt, easiest, pull the dizzy cap and try to start, rotor spins, belt ok (does not mean it didn't jump teeth, though)

have you checked the spark? pull the plug and hold the negative electrode against earth (obviously following all safety precautions) try to start the car and see if there is spark.

have you checked the Injectors? Long screwdriver on injector - ear to the handle, turn the engine, listen for tick, no tick injector dead (rough test, better use noid light, if can spare cash) or check resistance of the injector using multi meeter.

the list of changed parts is extensive and un-necessary (esp ecu)

your issue does not seem to me to be ignition or fuel related, sounds mechanical

with all parts changed (unless some were dead) all signs point to timing belt (especially since it has cut out one day never to live again)[/b]

the spark test is not foul proof.
u can get a spark when its out of the engine, but still no spark when its inside the engine trying to ignite the petrol.
look for a blue/white spark, yellow/red spark is a weak spark. but the best thing is to change them when you are trouble shooting.

spark test devices only tells you if the electricity is flowing through the spark plug wires, not that the spark plug is working as it should inside the engine.

if you suspect the spark is the reason the engine isn't firing.
on the plug test look for color. blue/white for strong red/yellow for weak
check the resistance on spark plug wires, should be around 10k ohm per meter. can be more, my nissan patrol ran on wires with 160k ohm, but ran better on wires with 10k ohm
check rotor and distributer cap for corrosion, sand/file down or buy new.
check coil. primary resistance 0.72 - 0,88 ohm secondary 6000 - 30000ohm, check that the coil gets 12v.
check timing.


fuel pressure regulator / volum test

release pressure from fuel system.
check the volume from return, should be 190-200cc or 0.2L / 10sec.
u can run the pump by jumping yellow test connector by the maf

[929_owner]

the spark test is not foul proof.
u can get a spark when its out of the engine, but still no spark when its inside the engine trying to ignite the petrol.
look for a blue/white spark, yellow/red spark is a weak spark. but the best thing is to change them when you are trouble shooting.

spark test devices only tells you if the electricity is flowing through the spark plug wires, not that the spark plug is working as it should inside the engine.

if you suspect the spark is the reason the engine isn't firing.
on the plug test look for color. blue/white for strong red/yellow for weak
check the resistance on spark plug wires, should be around 10k ohm per meter. can be more, my nissan patrol ran on wires with 160k ohm, but ran better on wires with 10k ohm
check rotor and distributer cap for corrosion, sand/file down or buy new.
check coil. primary resistance 0.72 - 0,88 ohm secondary 6000 - 30000ohm, check that the coil gets 12v.
check timing.
fuel pressure regulator / volum test

release pressure from fuel system.
check the volume from return, should be 190-200cc or 0.2L / 10sec.
u can run the pump by jumping yellow test connector by the maf[/b]

Quick bump. I bought the car and now have it at home. I'm about 99% sure it doesn't have a fuel issue based on its behavior. Let's rule that out. The first times I crank it it is completely ready to fire up. I've even had it run start ONE time at 1k revs very smoothly, but die out a second later, so its clear the ignition system is working well enough. If everything distributor related has been changed out, and pretending fuel is not an issue that leads me to believe it is the crankshaft position sensor that is the problem.

According to the 929 shop manual there are 2 crankshaft position sensors? Can anyone shed any light on this? As far as the manual says there is one in the distributor and one dedicated one at the bottom of the engine. I removed the bottom dedicated sensor and cranked it and it still fires, or at least tries firing, which indicates that there must be another sensor here giving it some idea when to fire. Also with that sensor unplugged and removed it cranks and tries firing exactly as it does with the sensor plugged in. I think I have found the culprit, but can't find out until I get a replacement. Any second opinions here??