Ford 7.3L Power Stroke (1999-2003) :: Only 1/4 Throttle Under Acceleration
Nov 16, 2015
I just put a regulated return system, two external filters and two fuel pumps, and I am still have problems.
Under acceleration driving it drops to almost 20 psi and that only 1/4 throttle.
3/4 throttle drops to 10 psi and barely idel. Died twice a block away from my house of test drives.
Tank is done with mods, new cps, icp, and ipr.
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This morning on my way to work I pulled up to a light and the check engine light came on. I went to go and had no throttle response at all. The truck just idled through the intersection. About 45 seconds later the light went out and truck ran fine all the way back to work. What to look for or what it could have been.
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i got a 99 F250 powerstroke with 148K on its clock, i have a couple issues that i cant find a definitive answer for, 1 just started recently, Its an automatic and when it shifts into third around 40 mph the rpms drop to 1200-1300 or so, its done it since i got it, but recently it wont accelerate like it should or used to do, i have to put it down and make it downshift to recover.
Now I have no CEL. and it is still running perfect just has very little power, I do have a 4 inch turbo back exhaust and have a TS 6 position chip with i usually run in +50hp mode, but it does this in all positions. Now issue 2 is when its 30 degrees sometimes it will not start. It'll turn over with now fire. but if i cycle the key again it'll fire right up like a champ? It has a 4 month old starter and batteries and a month old alternator and i have tried several CPS' and Contently check the connections.
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My 7.3 has no throttle response, the code reader says pass, and there are no codes, would it do this even thow it has a bad TPS?
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Comming back from hunting today my truck suddenly lost power and stepping on the accelearator had no effect at all. We were on the highway thru the mountains but on a fairly level stretch for a few miles. Managed to pull the truck and toy hauler over and the engine was running fine but stepping on the accelerator had no effect. The check engine light came on every time I stepped on the throttle and went out when I released it. It started fine but no throttle response. Switched around a bunch of relays and checked the fuses and still nothing.
Not liking my parking spot i tried to see if it would move down the road at an idle but it would not. Then I thought to try it in 4 wheel low and as the shoulders were soft it wouldn't move forward so tried reverse and went back a foot, forward again and moved a foot and a half. did this several times and all of a sudden the throttle responded, took it out of 4 wheel and it ran fine all the way home. What would have caused this? I was ready to call a tow truck which would have been several hundred dollar bills for where we were and with the trailer
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I have a '01 7.3 Excursion 2WD. 220,000 miles. It has a 4" exhaust, K&N filter and Edge Reprogrammer set on emission illegal. It gets the best fuel economy and moves out very well for 8000 lbs. Recently, I started to feel a surge while making light throttle acceleration. For example, round a corner at 35 and try to gently resume the 45 Speed limit. It begins to accelerate and then cuts out or surges, sometimes several times. If I lay into it, it responds fine. I have serviced the air filter, the fuel filter, use synthetic Amsoil. I did notice a slight improvement after the service. Less frequent cutting out or surging. I also was in an area where Bio diesel is readily available. I added almost a full tank of B10 Bio and it seemed to work. Changed the fuel filter just after.
It has been cold for NC. This morning it was +14 when I started the truck. It seemed to finally catch on maybe 2 cylinders with lots o' white/ blue smoke. It cleared out in a few minutes and seemed to be hitting on all 8, or at least 7. Once it warmed up, it's fine. But I had the codes p0672, p0674, p0676, p0678. My question is: Is there a common thread in the fact that it appears that I lost 4 glow plugs on the same bank?
One arm chair quarter back's response to the surging, is that the under valve cover injector wiring harness may be breaking down, especially since the truck has 220,000 and the valve covers have never been off. I have a fresh turbo with the good wheel sitting ready. I have just been too lazy to swap it out. Would a fresh set of injectors be a wise choice, when I swap over?
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When I let off on the throttle the truck jerk forward a little. It does it some times when hitting the throttle too. I have changed u joints in the drive shaft. I noticed the carrier bearing has a little play (going to change it this weekend). But I wouldn't think that would cause this.
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I have a 99 F450 with the 7.3L in it. I brought it home the other day and parked it. Later I went to do something with it and I had no throttle response at all. I checked the wiring going in and coming out of the throttle position sensor. I have approx. 5 volts going in and the voltage sits at about .5 volts and rises as the accelerator is depressed on the outgoing wire. The other switch on the pedal is open and does close when the pedal is depressed, so it seems those are fine. I'm not sure what I'm supposed to have on the 3rd wire that goes to the TPS.
I have a Bully Dog tuner and it shows an exhaust back pressure sensor error and a couple of voltage errors to the accelerator pedal. I read somewhere that someone had an exhaust sensor short out and it starved the accelerator pedal from voltage or something like that but I do have good voltage at the pedal going in and out. I ordered a new sensor and tube.
If the exhaust pressure sensor was shorting out and I unhooked the wires could that make the pedal work if the sensor was the problem or would the accelerator pedal not work at all without that sensor being connected? (The old tube was somewhat plugged up and I saw it had a small rust hole in it)
If it's not the sensor, what else can I check? Where can I check under the hood to see if the wires from the TPS are getting power to where they need to? I assume they go to the computer and that tells the pump or whatever to give more fuel.
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Ok, still working out some issues: It may be normal, but I hear (not feel) a slight roar when I'm pressing throttle petal very lightly. Seems to do it as we'll when I'm backing off throttle but it stops when I let off pedal completely. Not there when I get into the pedal. Not the tires because it stops all together when I get off throttle and let it roll. Turbo maybe ? Rear end (wouldn't it do it even when rolling)? No vibrations at all....just a little roar.
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My 2002 f250 starts but has no throttle, I did replace the throttle body, still no luck, i did find a wire on the shiffter that had a bad spot , fixxed it still no throttle, code reader says it passes with no codes, I disconnected both batteries and waited 15 to 20 min, reconnected them, started the truck and let it idle for 20 min so what do i need to do now. I just cant figure it out....
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I have a 1999 f-250 super duty 7.3 .... Recently my truck has started making a humming noise when push the throttle and I can feel a slight vibration, the noise and vibration go away when I let off the throttle, I have changed all five u joints, both wheel bearings in the front, the steady bearing, changed tranny and both diff oils, put new brakes and calipers all around and pulled apart the hubs but I can't seem to find what's causing it. What it could be or what I could check? It has an 8 inch lift and is sitting on 37's and some performance upgrades, could any of that cause this ?
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My truck will set an idle fine but when I hit the throttle it will die.
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2000 F-350 7.3L no gauges or throttle, I checked the fuses and no luck....
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Ford catalog does not list the TPS for a 1999 7.3 Super Duty as a separate replaceable part which leads to replacing the whole throttle pedal assembly. I found this to be incorrect. If you have a throttle pedal assembly with separate TPS (separate 3 wire connector) and IVS (Idle Validation Switch 2 wire connector) just the TPS can be replaced.
This is a pic of my 99 with new TPS installed : [URL] .....
Without removing the whole assembly you only need to remove the 2 T25 screws and the connector to replace.
Since this part is listed for more then 20 Ford trucks I figured it would work in my 99 7.3. I bought a brand new TPS from Pete (F250_) that he could not use. He has a 2002 with one 5 wire connector. It works perfectly in my 99. Not sure if it will work in a 2000 or 2001 but if the TPS and IVS each have their own connector it should. Make a visual inspection to be sure.
Part DY-967 or F4SZ-9B989-AA - Potentiometer
I was going to go with a Dorman TPS but like PartsGuyED likes to say "OEM Baby". The OEM TPS through Ed is actually cheaper then the Dorman.
Side-by-side pic of the old and new TPS. Only the center rotating part is different but it fits and works just fine. It also has a better fit so there is less slop and almost immediate response.
NewOldTPS.jpg?t=1269362105
By the way, the original TPS was working fine so I have no idea what the symptoms of a bad TPS are. Since it was available I replaced it to have a spare and to see if this one would work. Both Pete and I thought it would and we were right.
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Background: '01 Excursion 7.3 4WD, 264,xxx miles, batteries less than three years old, new alternator [URL] .... , using an Edge Insight for digital readings.
Problem: I replaced the alternator about three weeks ago, first week all normal. Second week alt/battery idiot light comes on, then to add more frustration it is consistently inconsistent in its reading.
The volts (upon starting) jump around 11.6 - 12.1 when first starting. The light comes on while accelerating and goes off during no throttle while cold.
After warm-up the light will come on intermittently even though the reading is 13.0>, but never during off throttle.
It seems to do this more when cold but it does not completely stop when it's warm. Yes, I don't think that should be a factor but it is a reality .
I'm thinking it's a bad voltage regulator.
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I own a 2000 F250 7.3 Powerstroke 4x4. The only aftermarket engine modification I have is a Tymar intake. The problem I'm having started about 6 months ago in a very erratic fashion. I would pull up to a traffic signal and as the light changed to green, without warning the truck would have no throttle response. The engine was running fine; there was just no response as I stepped on the accelerator pedal. Usually when I put the transmission in neutral, revved the engine a few times, the throttle would come back on line. This happened 4 or 5 times over the summer and then went away completely until today. Today it came back with a vengeance. At one point I had to shut the engine down completely to restore throttle response. It's a bit unnerving when it happens in the middle of a busy intersection. I was told that it may be the throttle position sensor. Does this sound correct and does it need to be replaced?
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I own a 2000 7.3 6 speed with 175,000 miles. I just bought it less than a month ago and it is my first diesel.
About a week ago I stepped on the gas and it just had nothing. I have a TS 6 position chip that I unplugged as soon as I noticed the loss in power. When I first bought the truck it was incredibly fast and now it has nothing to it at all. I have to have it higher in the RPM's to go up hills (especially when its not warmed up). If I push the pedal down it will sound the same, boost will get to about 14 (without chip) and the truck doesn't let out any smoke but it just doesnt have any power at all. I recently towed another vehicle on a trailer and it really struggled with it, more than I thought a diesel should.
When the chip was in, the truck would let out black smoke even after I noticed the loss in power. That made me think that the engine was getting enough fuel. I thought there could be a boost leak somewhere but it still builds 14 psi. However, I do not feel boost kick in at all! When I first got the truck it would only build around 14-15 stock but it felt a hell of a lot faster and I could feel when boost would really kick in. I took off my intake and looked at the turbo and the fins are in great shape and there is little to no play.
What the problem could be? I don't have very much money to start dumping parts into the truck and Im not sure what to do. I guess my questions would be:
1) Is it a boost leak, fuel problem, or something else?
2) Could a gelled filter give me these problems?
3) What should I do and where should I start?
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A little background first on my 1999 Ford F350 7.3. A few months ago I noticed i had fuel in my coolant which lead me to a cracked injector cup. I replaced all 8 cups and since I had it apart, and I bought the truck used and didn't know what had been serviced, I replaced the injector o-rings, glow plugs, valve cover gaskets, and valve cover gasket wiring harnesses. Got it all back together and had been running great.
About a week ago I was parked with engine running and the stereo suddenly turned off. A few minutes later I turned the truck off and turned it back on about 10 minutes later and it wouldn't start. Batteries appeared dead so I jumped it and made it home. Took both batteries down to AutoZone and since they were under warranty got two new ones. Figured out my alternator was bad and not charging my batteries so I ordered a new one.
Up to this point truck has been running fine. Truck had sat in my driveway for the week while waiting for the alternator. While I was out of town my father in law went to use the truck and noticed it wouldn't start. He hooked some jumper cables up and got the truck started. He said as he drove off the truck had no power and smoke was pouring out the exhaust.
I charged the batteries and installed the new alternator. Truck starts great and seems to be idling normal. When I took it for a test drive it has no power when accelerating and black smoke pours out the exhaust. The truck will barely make it up any type of incline.
I thought maybe it was the injectors not firing. Wiring harnesses are plugged in and do not appear to be damaged. I did not remove the valve covers yet as it's not difficult but time consuming and I figured since I just replaced all of it that it should be ok. I did a buzz test and all injectors passed. I get no trouble codes or check engine light.
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2001 SD F-250 SuperCrew 4WD, 7.3L (completely stock), 114K miles, automatic
We took Dad's SD for a 600-mile trip yesterday and today. The oil had 2000 miles on it, and we checked it before we left. The oil level was half-way down the hatch-mark, so we had added a little over a quart of oil to top it off, and I think that we may have added a little too much. Last night, when we got to the hotel and got out of the truck while it idled, a lot of white smoke that smelled like burning oil (like when you spill oil on an exhaust manifold) was fogging out of the exhaust.
It did this for a minute or two, then cleared up. All day today, on the way home (300 miles), about every time that I let off of the throttle either going down the interstate or stopping at a red light or stop sign, white smoke would pour out of the exhaust briefly, then stop when accelerating or in the throttle going down the road. What is causing this? Would too much oil (a little over a quart too full) make it smoke like this? The truck runs strong, starts and idles good, and no 'check engine' lights came on the dash.
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I have read many different threads regarding the TPS sensor on the pedal and EBPV deletes on the E99 7.3L Powerstrokes. I am trying to troubleshoot some issues with my E99 7.3L. Usually on cool mornings and after not being started for awhile the truck will seem to be stuck in an Idle. This is an intermittent problem that doesn't always happen.
I cleaned the connections to the Tps and the IVS sensor and put them back in. No luck. On another note I am also seeing a reduction in fuel mileage and power like the truck is being restricted. I don't know if these symptoms are related or possibly their own issues. I am troubleshooting and possibly thinking it is the EBPV system that isn't working correctly. Considering doing an EBPV delete with a NON-EBPV Pedestal and Flange.
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7.3 2001 model starts ok at 32-35 F. Feels a bit sluggish / slow response on the road. Reach a hill after 3-4 miles. Engine temp then beginning to go above low level mark. 100 meters up the hill, going around 30 mph there is a sudden surge in the throttle although my pedal is steady. Going back a few minutes later, on flat ground at bottom of hill and with no accelerator pressure, the engine suddenly stalls. Starts fine again after I stop. The same history actually repeated on two separate days recdently on the same hill. CPS is recently replaced. Had some jerking before that, but not the behavior explained above. Current CPS is Delphi light grey. Recent fuel filter change and oil change as well
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