tps even new may be faulty. where did you get it at?

 

I do not think a hair dryer gets hot enough and do not know how you would get the sensor in the distributor hot enough without melting the cap or something with the heat gun. Might be able to heat the ignition coil with a heat gun but again you would have to be careful not to get it to hot.

 

I don't know if it's been mentioned before as I didn't read every post. When is the last time you did a full tuneup? Including a fuel filter.

I had a 91 Ranger that sent me into a tail spin trying to find the problem. It would do the exact same thing to me only it was when I turned to the right. I spent many hours with test equipment only to find out the fuel filter was clogged.

The truck only had 15k miles on it since the last filter change, so I ruled it out in the beginning. Only was it when my dad told me to change it again did my problems stop. Not saying this is the problem, however, as my dad said many years ago, stay simple in the diagnosis, it'll cure most problems.

Good luck.

 

Yes, so far it has been tuned up with replacing all spark plugs, spark plug cables, distributor cap, distributor rotor, fuel filter, pcv valve, ignition module, cleaned out the throttle body very well, ran Barryman's chemtool through both tanks, changed out air filter.

Wednesday it died 5 times, taking several minutes each time before it would restart (starter turns, but doesn't ignite). I hooked up the fuel pressure guage which showed 38 pounds engine off no start, and 30 pounds after I got it running. Took me 2 hours to drive 12 miles. Yesterday it never offered to die, ran fine. This morning, it tried to die once, recovered, ran fine.

No codes are being thrown.

So the parts that are suspicious based on feedback here are: throttle position sensor, fuel pressure regulator, idle air control valve, mass air flow sensor, ignition coil, distributor sensor, loose or bad connection somewhere.

I'm thinking if it was idle air control, throttle position sensor, mass airflow then a code should be thrown? Am I right or wrong?



Thanks for any tips!

 

To check the fuel system you need to ground pin#6 of the test connector with the key on and you should get 45 psi fuel pressure with no fuel coming out of the vacuum fitting of the fuel pressure regulator.
You can also take the vacuum hose off the fuel pressure regulator, plug it and run the engine. This will also give the 45 psi and if any fuel comes out of the fuel pressure regulator it is bad. With the hose on at idle you would get a fuel pressure in the lower 30s.
When you turn off the engine or have ungrounded pin #6 of the test connector watch how fast the fuel pressure drops, it should hold and then fall very slowly.

If it works like this than your fuel pressure regulator is OK.

The idle air control is a bypass device and it can not kill the engine if you have your foot on the gas pedal, it would be out of the picture.

I think you are right.

 

Well, it went days with no problems, but this morning died again, 2 blocks. After 30 minutes it still wouldn't start. Starter turning over, good fuel pressure. I manually pushed it half a block to a good spot, hooked it up with a tow strap behind my wife's minivan and towed it two blocks back to the house. And then it started.

But I decided doing something would be better than doing nothing. So I changed the ignition coil (just $16, and easy to get to, so no big deal). Ran fine getting me to the office. Too early to say if I fixed anything or not. The old coil definitely had discoloration due to heat on the bottom of it on the back end, so maybe was just old. Or maybe I just wasted $16 and an hour.

I caved in and bought the Chilton's manual, too, but haven't read it in any detail yet. I did notice that it says the Oxygen Sensor should be changed every 30,000 miles...is that true? I don't think mine has been changed in 180,000 miles. No codes from it and no reason so far to think it is related to my truck stalling.

 

Chiltons told me to test the Idle Air Control Valve to see if it was between 7 and 13 ohms.

I did that while truck was running...when I took it loose the truck stammered a little but continued Idling. It tested to 9.5 ohms, so it is in spec. However, when I plugged it back in the Engine surged for a few moments and then promptly died and wouldn't start, just like whenit stalls on the highway...won't start several minutes after stalling then starts okay. So can this IAC valve actualkly be in spec not throwing a code but still fail causing the engine to die?

I'm going down to get an oxygen sensor since Chiltons says to change that at 30,000 miles and I'm at 180,000.

Regards and thanks for the tips so far.

David

 

I think I would put my money on a distributor rather than an oxygen sensor.
Sounds like your IAC is fine.

 

I changed the oxygen sensor; the old one didn't look that bad but it had over 180,000 miles on it so probably needed changing. It only took 5 minutes to change it. Idled it for an hour, didn't fail. I'll test drive it later, after I change out the new TPS that is bad. I got a new distributor cap too, the other one, though fairly new is missing the carbon cap, so no big deal to change it.


I found my spark tester so next time it won't start I can test that. Fuel pressure has been testing good during the no-start interval after it stalls.

 

So, I cleaned the Idle Air Control Valve, replaced the distributor cap (again), put the old good TPS back on, put on a new oxygen sensor, took the battery loose to clear the codes, put it all back together and test drove it. No problems noted, running like a champ. No codes, no strange behavior. So will it stall or die again? I drove it 25 miles, highway and city. I turned it off and restarted it a few times. All seems okay, but in a few days I'll report back and tell you whether these measures finally got it.

Any other suggestions on items to test?

Thanks!

David

 

I guess it is a wait and see thing. Fuel consumption should be a little better. Depending on the condition of the old O2 sensor it may not be noticable. Looks like your are prepared for the next failure with spark tester and fuel gauge which makes a lot of sense to me. Intermittent problems are the hardest things to diagnose. Keep us informed .

 

Okay...finally it stalled in my driveway this morning...

By the way, it is running great! Except when it's not.

So, I start it, warm it up real good, then kill it to take the keys and lock up my front door. Come back, starts fine again, but in about 1 minute stalls before I even put it in gear...just seemed to idle down slow suddenly and conked. Wouldn't start back up. Starter was turning normally. I hooked up the fuel pressure guage, got over 30 pounds to the injectors. Hooked up the spark tester on the wire going from the coil to the distributor cap --- no spark on crank. Looked at wires, parts that I could see, nothing seemed wrong. I thought I heard some kind of click, not a loud one. Checked again, getting spark. Hooked the cable back up, it starts instantly on crank and runs fine all the way to my work place.

I'll dig out the Chilton's when I get home, and see what I can find out.

Any thing jump out at you? I realize the computer *could* be the problem, but I think the click and lack of spark are good clues. I have recently changed the coil and TFI module, so those aren't suspects. Could be ignition switch, butu that click I heard makes me think it's in the engine compartment, which probably rules out the coil, ignition switch, tfi module and computer. Hmmmmm.....a sticking relay somewhere in the sequence?

No codes being thrown.

Thanks for any tips!

David

 

I still say you need a new stator assy/pickup coil which is located inside the distributor. Motorcraft is around $45 to $50, and an off brand can be found for around $20.

 

Sounds like the EEC Power Relay is going is not staying made. I think I would look at the Ignition Switch, its plug and the wiring under the EEC Power Relay.

 

I swapped around the relays this weekend. Nothing doing, still stalls. Yes that was me you were flipping off for being stuck in the left turn lane on highway 199! 5 minutes later it started.

Here is the deal, when it dies: some times it hesitates just before it dies, other times it just dies suddenly. Sometimes it dies and restarts itself before I do anything. No codes being thrown at any time. Then it is hard to start. Checked fuel pressure, that stays good. No spark is there between the ignition coil and the distributor cap during the no-start time. Suddenly the spark comes back after random several minutes and it will start.

Things changed so far:
Throttle position sensor, tfi ignition module, distributor cap, spark plug wires, ignition coil, spark plugs, relays, air filter, oxygen sensor, battery, fuel filter, pcv valve

Things checked not changed: Idle Air Control Valve (Idle Speed Control), error codes (none found), checked all the readily reachable wiring, alternator, egr vacuum

Remaining possible parts involved in failure: ignition switch, condensor element, pick up coil, computer (EEC), distributor assembly, wiring issue.

This certainly seems to be heat or time related, it only dies after I have been driving several minutes, and pretty much always on deceleration. It could just be random, but sort of seems heat related based on "when" it is stalling.

Thanks for your continued brain share...what would you test next?