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1994 3.0 No Start
Hey there,
I’ve been having problems with my dads truck and was wondering if you could help. It ran great then recently I would have to leave the key in “run” position for a minute before cranking it to start. Once it was hot it would start no problem. Fast forward another month into that, I went to take it to the store and it died while I was going about 40mph. I managed to start it by leaving key in the on position and got it home. After that it won’t start. My dad has replaced the fuel pump, ignition coils, distributor, and it still won’t start. We checked the relays and fuses by the battery and they all work as they should. We got it started one time while working on it by using starter fluid but wouldn’t start again next morning. Checked inertia switch already as well. Sometimes has spark, sometimes doesn’t. Check engine light in “run” position sometimes doesn’t show up not sure if that matters. We are at a loss of ideas now and would appreciate any help. Best Regards, John |
Welcome to the forum
In a 1994 3.0l the computer runs the fuel system and there is a separate module that runs the spark 50/50 test is when you spray fuel into the intake manually and then try to start engine If it starts, runs and dies then its a fuel issue If it doesn't start/fire then its a spark issue 50/50 instant results, test has been around since the 1890's, lol, so time tested Your spark system is TFI, doesn't need the computer to work In the 3.0l Ranger its in the front of engine bay driver side mounted on rad support, has cooling fins with TFI module in the center It has 3 or 4 wires to distributor, and 12v and ground wires TFI Modules would get heat sensitive, but more of an issue when there were mounted to the distributor like on the 2.9l Ranger, thats why the 3.0l got the "remote mounted TFI" One thing to look for, CEL(check engine light) CEL should come on with key on, that means computer has booted up, no CEL means maybe no 12volts at computer OR TFI When you turn the key to START the CEL should go OFF as soon as engine turns a few RPMs, this means the TFI and computer "see" a timing pulse from the sensor inside the distributor, called a PIP signal No spark and no injectors without this timing signal Down by the TFI module there should be a SPOUT connector, has a plug in that can be pulled out, this disconnects spark advance coming from the computer, engine will start and run without this connection, its just there to set Base Spark timing at 10-12deg BTDC, pulling this plug in is the same as removing the Vacuum advance hose to set base spark timing on the older engines So if 50/50 test has a no start then either spark is disabled or far enough out of time to get a no fire Once you have reliable start up using 50/50 test you can move on to computer and fuel system as needed As said the spark system autonomous, distributor, TFI module and coil, all will work without computer connection |
Originally Posted by RonD
(Post 2202636)
Welcome to the forum
In a 1994 3.0l the computer runs the fuel system and there is a separate module that runs the spark 50/50 test is when you spray fuel into the intake manually and then try to start engine If it starts, runs and dies then its a fuel issue If it doesn't start/fire then its a spark issue 50/50 instant results, test has been around since the 1890's, lol, so time tested Your spark system is TFI, doesn't need the computer to work In the 3.0l Ranger its in the front of engine bay driver side mounted on rad support, has cooling fins with TFI module in the center It has 3 or 4 wires to distributor, and 12v and ground wires TFI Modules would get heat sensitive, but more of an issue when there were mounted to the distributor like on the 2.9l Ranger, thats why the 3.0l got the "remote mounted TFI" One thing to look for, CEL(check engine light) CEL should come on with key on, that means computer has booted up, no CEL means maybe no 12volts at computer OR TFI When you turn the key to START the CEL should go OFF as soon as engine turns a few RPMs, this means the TFI and computer "see" a timing pulse from the sensor inside the distributor, called a PIP signal No spark and no injectors without this timing signal Down by the TFI module there should be a SPOUT connector, has a plug in that can be pulled out, this disconnects spark advance coming from the computer, engine will start and run without this connection, its just there to set Base Spark timing at 10-12deg BTDC, pulling this plug in is the same as removing the Vacuum advance hose to set base spark timing on the older engines So if 50/50 test has a no start then either spark is disabled or far enough out of time to get a no fire Once you have reliable start up using 50/50 test you can move on to computer and fuel system as needed As said the spark system autonomous, distributor, TFI module and coil, all will work without computer connection So we did what you said (took out the spout) and now we have spark but there’s no pulse to the injectors. Could it be the PCM or the distributor? Thanks! |
So engine starts, but dies with 50/50 test, thats good it means spark is strong enough, and timing is close enough
Does the CEL go off when starter is turning the engine over? If so then computer is getting timing pulse, if CEL stays on then its not SPOUT is SPark OUT, so won't effect this timing pulse one way or another, plugged in or unplugged, SPOUT signal is coming FROM the computer for spark advance PIP signal is what TFI module sends to the computer, the timing pulse the computer uses to start and time injectors, it runs to pin 56 on computer PIP comes from the sensor inside distributor, TFI uses it for spark timing and also sends it to computer If you haven't done this yet I would pull out computer and look at the connector, inside connector, and also open up the computer and look for corrosion or "burnt" areas |
Originally Posted by RonD
(Post 2202757)
So engine starts, but dies with 50/50 test, thats good it means spark is strong enough, and timing is close enough
Does the CEL go off when starter is turning the engine over? If so then computer is getting timing pulse, if CEL stays on then its not SPOUT is SPark OUT, so won't effect this timing pulse one way or another, plugged in or unplugged, SPOUT signal is coming FROM the computer for spark advance PIP signal is what TFI module sends to the computer, the timing pulse the computer uses to start and time injectors, it runs to pin 56 on computer PIP comes from the sensor inside distributor, TFI uses it for spark timing and also sends it to computer If you haven't done this yet I would pull out computer and look at the connector, inside connector, and also open up the computer and look for corrosion or "burnt" areas Fires right up now! You really know your stuff and you were very helpful! We really do appreciate it! Best Regards, John |
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