grover said:
Curtis73 (Forum Supporter) said:
Mine was an early 95, so OBD1, but the only thing the brake light circuit controlled was telling the ECM to unlock the torque converter. 96 is OBD2 so it may do something else as well?
Wouldn't that cause his issue? I admit to being fuzzy about TC's outside of stall speeds.
Maybe? In general the TC does not unlock when the problems occur, it keeps spinning the engine at the "correct" RPM, it feels and sounds just like it wants to idle instead. Also, the problem does not necessarily happen when I put the brakes on. Just taking my foot of the gas (diesel?) pedal is enough.
In other news I just checked and the third brake light is indeed not working so I should probably put a new bulb in.
The only thing I have to offer is when my wife's 1991 IDI "dumb diesel" was doing something similar it was diagnosed with a bad injector pump.
it only ever cuts out when I fully close the throttle while coasting, usually downhill -
My wife's truck started acting up that way. After a few weeks of this it would stall when the throttle was released pulling up to a stop light. On deceleration the injector pump was cutting off fuel to the engine. YMMV, no one anywhere has endorsed this attempt at finding the problem. Good luck, and stop calling me Shirley
In reply to noddaz :
Was that an intermittent issue? One of the reasons for this being such a PITA is that it's an intermittent problem and usually, shops can't reproduce it unless I'm willing to have the mechanic drive around for a few hours.
Tim,
Is a Tundra in your future ?
In reply to mr2s2000elise :
I don't quite feel that flush 
, but that's a possibility. I don't really need an expensive truck (but then again, rust...) as I only do about 3k-4k miles in my trucks annually anyway, but I need something reliable.
I'm actually considering a Ford Excursion or a Suburban/Escalade as a truck substitute. Most of the time, the stuff I put in the bed is reasonably clean so there isn't much need for a "real" truck, but I'd prefer something that's F250-sized, at least from a heavy duty-ish perspective. Either that or I may have to get a lighter trailer.
BoxheadTim (Forum Supporter) said:
In reply to noddaz :
Was that an intermittent issue? One of the reasons for this being such a PITA is that it's an intermittent problem and usually, shops can't reproduce it unless I'm willing to have the mechanic drive around for a few hours.
It started out that way and finally ended up stalling every time the truck was driven. I called a diesel specific shop that I had done business with my issues and their reply over the phone was it needed an injector pump.
That being said, your truck is a few years newer and your truck is a turbo. And I will throw this out there also because I don't know. Will a boost leak cause that? That would seem less intermittent and more that it would happen all the time.
I dunno, you have a fleet of somewhat broken down vehicles. I'd rather just have 3-4 vehicles that just plain work. That way I can do the fun wrenching on them. Sell the truck, sell the S2000, sell that whatever track only thing you just bought is. Keep the Jeep, keep the Alfa. Buy a Tundra and an E46 M3 and call it good already.
BoxheadTim (Forum Supporter) said:
grover said:
Curtis73 (Forum Supporter) said:
Mine was an early 95, so OBD1, but the only thing the brake light circuit controlled was telling the ECM to unlock the torque converter. 96 is OBD2 so it may do something else as well?
Wouldn't that cause his issue? I admit to being fuzzy about TC's outside of stall speeds.
Maybe? In general the TC does not unlock when the problems occur, it keeps spinning the engine at the "correct" RPM, it feels and sounds just like it wants to idle instead. Also, the problem does not necessarily happen when I put the brakes on. Just taking my foot of the gas (diesel?) pedal is enough.
In other news I just checked and the third brake light is indeed not working so I should probably put a new bulb in.
I suppopse it could cause the issue. I wish I could be there and poke at it in person. In all of my powerstrokes, (which right now is sadly zero) the TC at least partially unlocked during decel. They are PWM, so it's not always fully locked or fully open. In a situation like downhill towing, if you let up on the pedal, the RPMs drop even though you don't slow down indicating that the TC is not fully locked.
When you're moving slowly (under 35 or so) and take your foot off the pedal, all of mine returned basically to idle.
I will also mention that these diesels will defuel. By that, I mean they are much like some EFI gas engines. If the engine is spinning faster than idle but your foot is not on the pedal, it doesn't inject fuel. You may have noticed this. If you downshift to get engine braking, the engine just moans or hums, then as you slow down and it approaches idle you start getting cackles of diesel flame as it starts to inject again. If you're on the highway going downhill with your foot off the pedal and you turn off the switch for a second or two, you won't notice a difference at all. (don't do that though... standard disclaimer). That's because the computer isn't doing anything at that point. The TC is likely not being controlled, the engine isn't injecting fuel, so there is no change when you turn the key off.
BoxheadTim (Forum Supporter) said:
In reply to mr2s2000elise :
I don't quite feel that flush , but that's a possibility. I don't really need an expensive truck (but then again, rust...) as I only do about 3k-4k miles in my trucks annually anyway, but I need something reliable.
I'm actually considering a Ford Excursion or a Suburban/Escalade as a truck substitute. Most of the time, the stuff I put in the bed is reasonably clean so there isn't much need for a "real" truck, but I'd prefer something that's F250-sized, at least from a heavy duty-ish perspective. Either that or I may have to get a lighter trailer.
Makes sense!
suburban /excursions are cool ! Good luck on the new purchase
In reply to Curtis73 (Forum Supporter) :
I didn't realise these had a fuel cut for decel. Suddenly things make more sense in a "not starting to fuel properly after the fuel cut" way. I suspect that keeping my foot on the go pedal (and thus not triggering the throttle closed switch) prevents the fuel cut and then everything keeps working...
BTW, I'm not that far away 
. I actually have to travel up to your neck of the woods pretty soon, but with the "wrong" vehicle.
Yeah. Try it some time. When you're doing something like 40 mph, downshift to 2nd and let off the throttle. As you decel, the motor will hum and make noise, but it's just spinning because the transmission is pushing it. Then as you get down to around 1000 rpm you'll start hearing little cackles as it starts injecting fuel.
Although your current issue might not give you an accurate demonstration of that.
If you're bored some day, take a video of you driving the truck and showing the trouble.
In reply to A 401 CJ :
I find oilburners.net to be helpful. Not as helpful as GRM of course, but still helpful.
Gack, things have gone from bad to worse and it currently resides at the local shop of least mistrust for diagnosis.
I noticed it felt down on power when I ran down to Baltimore to pick up the Honda CB400 I bought and started cutting out a lot more often, then the next morning it got cold and the truck became really hard to start. Like no glowplugs, but I could hear the glow plug relay click and all 8 glow plugs are less than two years old. Started OK when it was warm, but on the way to pick up the new tires for the Maxton, it kept cutting out at lower speeds than it ever had before.
The day I took it to the shop, it barely started in 70F weather, which IMHO rules out the glow plugs.
Hard to start when cold and down on power is usually not that great a combination when it comes to oil burners...
After two Ford sensors and one aftermarket sensor, a 3rd new Ford crank sensor fixed a 7.3 problem child.
I find it hard to wrap my head around 3 bad (new) sensors in a row. But it appears a new sensor fixed it.
This was after hours of diagnostic work parts swapping and even a wire harness swap.
In reply to bentwrench :
I should probably let the shop know that there is a brand new black OEM sensor in the glove box that might want to find its way onto the front of the engine.
My concern is that it feels like back when it had HPOP issues, only that those normally materialise when the engine is hot, not cold.
The trick is to buy the new cps sensor ahead of time and IMMEDIATELY swap it in. Use the known good one as the spare.
Hearing the click on the glow plug relay unfortunately means zilch.
What you need to do is focus on the voltmeter. Turn the key on, and when you hear that click, watch the voltmeter. If it drops a half volt, there is no load. If it drops 1-2v, the plugs are heating.
GPRs go bad and still click, but don't send juice. The wires for the glow plugs are molded into the valve cover gasket and they sometimes fail.
But in 70 degrees, it should start without plugs. Mine were a wee bit fresher than yours, but I noticed that somewhere around 40F was the cutoff depending on other factors like humidity/density/altitude. When I was in Los Angeles, one of mine had a GPR fail so I just disconnected it. Drove it for three years like that. Only reason I fixed it was because I sold it to a guy in Nevada and he would need it.
In reply to Curtis73 (Forum Supporter) :
It certainly used to start without plugs in that sort of temperature range. Like you described it usually didn't need plugs u til the mid forties.
Any chance all of this is a voltage issue? Is the regulator in the alternator? Possible bad ground? Is the ecu plug working loose? Stranger things have happened to folks.
bentwrench said:
After two Ford sensors and one aftermarket sensor, a 3rd new Ford crank sensor fixed a 7.3 problem child.
I find it hard to wrap my head around 3 bad (new) sensors in a row. But it appears a new sensor fixed it.
This was after hours of diagnostic work parts swapping and even a wire harness swap.
I'm going to go out on a limb, and guess this was at a shop, and not troubleshooting yourself. VERY few shops diagnose problems. They replace parts till the problem goes away, and charge you for all the parts that it didn't even need. And the labor to replace them one at a time.
Curtis is def. a good resource. After a few di 7.3's, and a cat with same injection system, I got to know it pretty well. Check the HPOP side out well. Shops have been known to miss stuff!
One thing that 99% of 95 to 97 7.3' never get cleaned when doing a fuel filter, is a HP part of the housing. If I find my old you so g I can show a picture of the smaller assembly bolted to it, but I don't recall the name... Curtis might. Inside one of the passages is a wad or SS filter media that needs to be removed and cleaned every several filter changes. So far, the guy that told me about it is only person I've ever talked to that knows its there. Its in about a 1/4" dia passage. When you remove the smaller bolt on housing, there is a tiny check ball... If you loose it in the grass, it is listed on Ford's exploded diagram, but not available separate. Ask me how I know. Entire filter housing, complete with sensors fittings and filter was discontinued at ford, but I found a nos on shelf next town over for $385.98... For a part I was planning to replace soon with Strickly Diesels regulated return system!
That screen element may not be the only cause, but it WILL cause that symptom. And degrade performance slowly over time that most never even notice... Till after I clean it for them
A pretty good way to clean that screen (depending on what's stuck in it) is some diesel injector cleaner fluid. Dump a half cup in the filter housing, throw some saran wrap over it and let it sit for a couple hours. Re-assemble if it looks clean.
If I recall correctly, that is the inlet screen from the low pressure sensor/regulator? Jeez. Been too long. Getting rusty.
In reply to Curtis73 (Forum Supporter) :
I think you named it correctly... Like you, haven't put my hands on one in about 7 to 8 years, and my brain ain't as sharp as it used to be!
But as long as ya don't loose any parts, it's well worth removing to clean. Needs a back flush,not just a soak.
