Bad miss under load. Low mileage 7.3L - Diesel Forum - TheDieselStop.com
'99 & up 7.3L Power Stroke Engine and Drivetrain Discussion of the '99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.

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post #1 of 15 (permalink) Old 12-22-2016, 02:42 AM Thread Starter
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Exclamation Bad miss under load. Low mileage 7.3L

Sorry, this is a bit long, but I wanted to put all the details out there from the start.
Here's the setup:
2001 F-250 4x4, 7.3PSD, ZF 6-Speed, DP Tuner switch chip, 4" turbo-back, South Bend Clutch and solid FW, Gear Venders O/D, and 3.73 gears.

I've had this truck stored in my shop for about 8 years. Dry, warm area. Started and warmed up once a year or so.
It has only 84,000 miles and was my Dad's truck, and means a lot to me.

Anyway, I needed to tow my race trailer to Florida and back.
I put tags on it, Changed the oil with Rotella 5w40 Synthetic, and took it by the dealer to address the CPS and cruise control switch recalls. They replaced the CPS and added the fusible link to the CC switch.

Filled it up and left for FL with the empty trailer.
Drove approx 750 miles with the DP set to the 60HP tow mode, everything running fine and EGT at 800 deg at 75mph cruise (1,700 rpm).
The last hour or so, I did notice EGT's creeping up to around 900deg, I thought the warm FL air may be the cause.

Suddenly, it lost power and started missing badly. I cancelled the cruise and whenever I gave it fuel, it started missing, with low power, and higher EGT's. Boost was lower as well. I had filled up about 100 to 150 miles before this started. I nursed it along to a service station, thinking the fuel filter may be clogged.
They didn't have the filter, so I drained a few ounces from the bowl, which looked clean and free of water.
Primed and refired, and it ran normally the remaining 40 miles.

Next morning, again ran fine going to get a new filter. Changed the filter out, and the old one was pretty dark. Fuel bowl was clean.
Reprimed and started up, and went to load up the trailer.

Again, it ran fine for around 700 miles coming home, this time with around 8,000 or 9,000 lbs in tow.
Did the same thing about 100 miles from home. Tried draining the filter several times, but only cleared it up for a few miles at best.
It did come and go, sometimes running fine for 10 miles or so, then missing and slow for a while.
At first it seemed it would clear up for a while after descending a hill, but once it cleared up while trying to maintain speed climbing a slight hill as well.
Naturally, when it would start missing I backed off, downshifted and tried to keep engine load as low as possible, which reduced the shaking.

Anyway, after draining the bowl the final time, when I turned the key on to prime, the fuel pump seemed a bit louder than I remember it being.

At no time did I get a CEL or any other indicators on the dash. I have the Torque App and a Bluetooth Dongle that I took along out of curiosity, and the few parameters I had setup to monitor all looked normal as well.

My thinking is it needs a new fuel pump at a minimum. Other educated opinions are welcome.

I know this truck has a frame mounted fuel pump, but is there another pump in the tank?
Is there a strainer in the tank that I can change as well.
I plan to drop the tank either way, just to make sure there's no algae or other crud in there from storage or from a dirty load of fuel, and to modify the vent so it doesn't take 10 minutes to fill it up.
Also, unfortunately this is likely the first ULSD and biodiesel blended crap this truck has drank as well. I wonder if that could've caused the problem? That crap seems unavoidable nowadays.

Any advice is appreciated, unless you intend to jump me about not driving the truck more.

Thanks in advance,
David

David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.
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post #2 of 15 (permalink) Old 12-22-2016, 07:05 AM
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Know you changed oil but suggest verifying oil level. If low the injectors will drop in and oil. Fuel restrictions usually menifest in fade out in power. Try to get codes, run all built in self tests. Look for chewed or chased wires by driver's side valv cover where engine harnesss lays on valve cover. Look for burnt wires where CPS wires get near the EBP tube on front of engine.
BTW trucks that sit often get moved into by wire chewing vermin.
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post #3 of 15 (permalink) Old 12-22-2016, 07:30 AM
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Good luck from a fellow Virginian and a fellow 2001 with 80k miles and a fellow 6 speed and a fellow 3:73.... However, one thing that confuses me is that you say 75mph = 1700rpms.
This is not the case on my 2001/3:73, at 75mph I am well over 2000rpm and somewhere around 2200.
It makes me think of the CPS, maybe they didnt get it installed exactly right.

2001 Lariat, F250, 7.3, 6-speed, 3:73, Ford AIS, MBRP 4" turbo back, ATS ported housing, 205 t-stat, Infinity DX w/DP Tuner 80hp tow, coolant filter, Hutched & Harpooned, EGT & Boost gauge. Fuel Mavericks with 285/18, 86k miles(Jan-2017) Bought brand new April 2001.
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post #4 of 15 (permalink) Old 12-22-2016, 07:41 AM
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Quote:
Originally Posted by Cobranut View Post

I know this truck has a frame mounted fuel pump, but is there another pump in the tank?
Is there a strainer in the tank that I can change as well.
I plan to drop the tank either way, just to make sure there's no algae or other crud in there from storage or from a dirty load of fuel, and to modify the vent so it doesn't take 10 minutes to fill it up.
Also, unfortunately this is likely the first ULSD and biodiesel blended crap this truck has drank as well. I wonder if that could've caused the problem? That crap seems unavoidable nowadays.


Thanks in advance,
David
There is not another pump but there is a pickup assembly in the tank that includes a mixing chamber with 2 screens that are notorious for clogging up. It is a flawed design and the way to fix it is to do the Hutch mod.
Welcome to guzzle's In-tank Hutch Mod Web Page

The Harpoon mod will take care of the slow filling issue:
http://www.guzzle7pt3.com/harpoon.php

Brian, Tucson, Arizona
02 F350 4x4 CREW 7.3 170K, BFG Rugged Terrain 285s, AIS, Isspro pyro, boost & tranny temp pillar pod, Dipricol coolant temp, ELC, Isspro EV-2 Fuel Pressure & HPOP, Dieselsite boots, coolant & tranny filters & 203* Stat, 6.0 Tranny Cooler, ITP pre pump tank mod, Bellowed Up Pipes, Riffraff Frx, netbook mount with AE, GPR LED, Stancor, Red Head steering gear, Battery Tender & 2 Marincos.
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post #5 of 15 (permalink) Old 12-22-2016, 10:02 AM Thread Starter
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Quote:
Originally Posted by aclasshog View Post
Good luck from a fellow Virginian and a fellow 2001 with 80k miles and a fellow 6 speed and a fellow 3:73.... However, one thing that confuses me is that you say 75mph = 1700rpms.
This is not the case on my 2001/3:73, at 75mph I am well over 2000rpm and somewhere around 2200.
It makes me think of the CPS, maybe they didnt get it installed exactly right.
That's in 6th gear with the Gear Vendors engaged.
Thanks.

David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.
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post #6 of 15 (permalink) Old 12-22-2016, 05:00 PM
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The old recalled CPS sells for over $150 on Ebay.

They are very popular.

Any chance you can get it back?


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2002 F-250 4x4 CC SB 7.3 PSD w/4R100. 182,000 miles.
NOS Black CPS. ScanGauge-II, AIC, Bilstein 5100, Stancor GPR, Marinco Mod, B&W Turnover Ball, Michelin Defender LTX


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2002 F-250 4x4 SC LB 7.3 PSD w/ZF-6. 177,000 miles.
NOS Black CPS. ScanGauge-II. Bilstein 5100. Stancor GPR. Walker BTM. Noco Mod. Michelin Defender LTX 285/75/16.

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2000 F-250 4x4 SC SB 7.3 PSD w/4R100. 164,000 miles.
NOS Black CPS. Rebuilt Fuel bowl w/gold spring, 6.0 Cooler, Walker BTM, Stancor GPR, Michelin LTX M&S2.
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post #7 of 15 (permalink) Old 12-22-2016, 05:09 PM
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The diesel sold today cannot be more than 5% Bio unless the pump is marked in most States. The Bio-fuel is typically of good sources and actually provides great lubrication to the fuel now that ULSD is all that is available. Ofcourse, the only downside is its quite a solvent. ULSD has been the only diesel available for several years so if this is the first tank then your old fuel must have been quite old and real junk by now.

Good plan to clean the tank and worth adding a Biocide.


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2002 F-250 4x4 CC SB 7.3 PSD w/4R100. 182,000 miles.
NOS Black CPS. ScanGauge-II, AIC, Bilstein 5100, Stancor GPR, Marinco Mod, B&W Turnover Ball, Michelin Defender LTX


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2002 F-250 4x4 SC LB 7.3 PSD w/ZF-6. 177,000 miles.
NOS Black CPS. ScanGauge-II. Bilstein 5100. Stancor GPR. Walker BTM. Noco Mod. Michelin Defender LTX 285/75/16.

SOLD:
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2000 F-250 4x4 SC SB 7.3 PSD w/4R100. 164,000 miles.
NOS Black CPS. Rebuilt Fuel bowl w/gold spring, 6.0 Cooler, Walker BTM, Stancor GPR, Michelin LTX M&S2.

Last edited by ArcticDriver; 12-23-2016 at 04:25 PM.
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post #8 of 15 (permalink) Old 12-22-2016, 07:06 PM Thread Starter
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Quote:
Originally Posted by ArcticDriver View Post
The old recalled CPS sells for over $150 on Ebay.

They are very popular.

Any chance you can get it back?

Thanks, I'll call the dealer, but I doubt they'll return it. The mechanic probably knows this as well. ;-)

Why is there a demand for the old CPS? The whole reason for replacement was that they were failure-prone.
The original one failed when the truck was almost new, and was replaced under warranty several years before the recall was issued.

David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.
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post #9 of 15 (permalink) Old 12-22-2016, 07:10 PM Thread Starter
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Quote:
Originally Posted by bigb View Post
There is not another pump but there is a pickup assembly in the tank that includes a mixing chamber with 2 screens that are notorious for clogging up. It is a flawed design and the way to fix it is to do the Hutch mod.
Welcome to guzzle's In-tank Hutch Mod Web Page

The Harpoon mod will take care of the slow filling issue:
Welcome to guzzle's In-tank Harpoon Mod Web Page
Thanks for the links. I'll do both those mods when I get the new fuel pump.

I got the truck all cleaned up today, and each time I started it, the fuel pump sounds worse. I think we were lucky to make it home before it seized up completely.

David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.
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post #10 of 15 (permalink) Old 12-22-2016, 07:19 PM
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Quote:
Originally Posted by Cobranut View Post
Thanks for the links. I'll do both those mods when I get the new fuel pump.

I got the truck all cleaned up today, and each time I started it, the fuel pump sounds worse. I think we were lucky to make it home before it seized up completely.
You might not need a pump, it might be making noise because it is being starved.

Brian, Tucson, Arizona
02 F350 4x4 CREW 7.3 170K, BFG Rugged Terrain 285s, AIS, Isspro pyro, boost & tranny temp pillar pod, Dipricol coolant temp, ELC, Isspro EV-2 Fuel Pressure & HPOP, Dieselsite boots, coolant & tranny filters & 203* Stat, 6.0 Tranny Cooler, ITP pre pump tank mod, Bellowed Up Pipes, Riffraff Frx, netbook mount with AE, GPR LED, Stancor, Red Head steering gear, Battery Tender & 2 Marincos.
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post #11 of 15 (permalink) Old 12-22-2016, 09:07 PM Thread Starter
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Originally Posted by bigb View Post
You might not need a pump, it might be making noise because it is being starved.
That may be true, but if it's been starved, it may be damaged, so I'll replace it anyway.
The Bosch replacement is well under $100, so it's cheap insurance.
I'll probably buy a spare CPS to keep in the truck as well, since it sounds like the new ones aren't much more reliable than the old ones.

Thanks.

David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.
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post #12 of 15 (permalink) Old 12-22-2016, 10:26 PM
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I would just about put money on it being just the screens in the tank. I had the same issue and did the hutch and harpoon mod and it has been fine since.

2002 f250 7.3 4x4 256,000miles. Bone stock other than hutch mode and edge evo programer I use for gadges most of the time. I also have air bags on back for towing.
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post #13 of 15 (permalink) Old 12-23-2016, 04:59 PM
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Quote:
Originally Posted by Cobranut View Post
That may be true, but if it's been starved, it may be damaged, so I'll replace it anyway.
The Bosch replacement is well under $100, so it's cheap insurance.
I'll probably buy a spare CPS to keep in the truck as well, since it sounds like the new ones aren't much more reliable than the old ones.

Thanks.
As for a new CPS. There is a very in-depth thread about CPS choices on here. If you want to stick with Ford/Motorcraft / IH then I recall guys are having better luck with the "Purple" CPS made for 99 & earlier 7.3's even in our newer engines.

Use the purple and throw you new Ford installed CPS in the glove box for your spare. It should be grey colored.


Gray (IH # 1876735C91 / Ford # F7TZ-12K073-B)

Blue/Purple (IH # 1825899C93 / Ford # F4TZ-12K073-C)

Black (IH # 1825899C93 / Ford # F7TZ-12K073-A) (Out of manufacture and recalled by Ford but still popular).


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2002 F-250 4x4 CC SB 7.3 PSD w/4R100. 182,000 miles.
NOS Black CPS. ScanGauge-II, AIC, Bilstein 5100, Stancor GPR, Marinco Mod, B&W Turnover Ball, Michelin Defender LTX


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2002 F-250 4x4 SC LB 7.3 PSD w/ZF-6. 177,000 miles.
NOS Black CPS. ScanGauge-II. Bilstein 5100. Stancor GPR. Walker BTM. Noco Mod. Michelin Defender LTX 285/75/16.

SOLD:
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2000 F-250 4x4 SC SB 7.3 PSD w/4R100. 164,000 miles.
NOS Black CPS. Rebuilt Fuel bowl w/gold spring, 6.0 Cooler, Walker BTM, Stancor GPR, Michelin LTX M&S2.
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post #14 of 15 (permalink) Old 01-07-2017, 09:46 AM
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Cobranut,

How did you finally get this sorted out?

Thanks
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2002 F-250 4x4 CC SB 7.3 PSD w/4R100. 182,000 miles.
NOS Black CPS. ScanGauge-II, AIC, Bilstein 5100, Stancor GPR, Marinco Mod, B&W Turnover Ball, Michelin Defender LTX


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2002 F-250 4x4 SC LB 7.3 PSD w/ZF-6. 177,000 miles.
NOS Black CPS. ScanGauge-II. Bilstein 5100. Stancor GPR. Walker BTM. Noco Mod. Michelin Defender LTX 285/75/16.

SOLD:
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2000 F-250 4x4 SC SB 7.3 PSD w/4R100. 164,000 miles.
NOS Black CPS. Rebuilt Fuel bowl w/gold spring, 6.0 Cooler, Walker BTM, Stancor GPR, Michelin LTX M&S2.
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post #15 of 15 (permalink) Old 05-03-2017, 08:42 PM Thread Starter
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Quote:
Originally Posted by ArcticDriver View Post
Cobranut,

How did you finally get this sorted out?

Thanks
Hello again.
I had some other projects that were higher priority, so this got put on the back burner for a while.

I finally got the truck on the lift last weekend and dropped the tank.
First off, the pickup foot was broken off at the end where it clamped to the mixing chamber, so there was no way it would pick up the last several gallons of fuel.
The tank was absolutely spotless inside, no signs of sludge or algae or anything else. (Gotta love diesel for long-term fuel stability).
When I disassembled the mixing chamber, however, the two strainer cartridges were quite filthy with a dark pasty coating, and some small grainy feeling particulates.
I replaced the pump with a new Bosch pump, and the rest of the fittings are due by Friday.
Instead of another failure-prone pickup foot, I ordered a stainless 40 mesh pickup screen,


, and used a Swagelock 3/8" npt adapter to mount it on the pickup extension. I also extended the return line.
Also, I ohm'd out the sending unit, and cleaned the contacts with some acetone on a q-tip. I'd replace it while I'm in there, but I can't find the sender without the entire pickup assembly, which is pretty pricey.

I plan to get it all back together this weekend.

Here's a few shots so far.

Thanks to everyone for the help and suggestions.

David
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David

2001 F-250 4x4 SC SB PSD 6-Speed, 3.73LS, Flo-Pro 4" Dual Exhaust, DP-Tuner F-5 , Gear Vendors OD, South Bend Con OFE Clutch, Peragon Folding Tonneau.

Last edited by Cobranut; 05-04-2017 at 07:53 PM. Reason: Add pics.
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