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Common 7.3 problems

374K views 72 replies 43 participants last post by  BartSmaalders 
#1 · (Edited)
Im going to make a list of common problems I've seen on 7.3 powerstroke motors 94-99
I've worked and owned over 7' 7.3s

Overlook your truck and rule out these problems one by one.
So if your symptoms are similar look into these problems.

If your looking to purchase a truck with a no start look into these. You'll know what to look for


These are COMMON problems some motors may have 1 or more of these issues.
There's more problems that can occur but these are what I have experienced.


Common No Start #1:
IPR VALVE, LOCATED IN THE VALLEY ON THE HPOP. these often stick, the sensors go bad
Or the wires get cut.
Replacement cost $140-300 New

Common No start #2:
IDM located on drivers side fender.
These could go bad and will cause a no start or ruff running and cut outs in revving/rpm.
Replacement cost $50-350 for used-new

Common problems #1 Cps sensor. Causes the truck to cut out and evuantually die. Making it not start until it sits or is reset on the batteries. Easy way to make sure yours is good; on OBS's check if you tach moves while cranking if it does your cps is good. If not replace. Cost $24-70 don't buy the sensor from any parts store get it OEM because they can be defective out of the box.

Common problem #2
UVCH. Connectors, when these go bad or ground out on your glow plugs they can cause horrible running conditions to the point where the truck sounds like ut has 17* timing and it lopes bad and will often die. &sputter. Easy way to fix this or check for it , there are four connectors on your block /heads that are under the valve covers unplug them and check for cut wires or burnt connectors if there burnt Replace them. Its not to hard and the average joe can do it.
Replacement cost $134-260$50-350 chines-oem ford

Common Problem #3
fuel filter clogged. Will often cause long cranking or semi loss in power if the injectors can't get the fuel they need the truck wont run its best
Replacement cost $9-30 easy to do

Common Problem #4
Lift pump failure, this will definitely cause a no start. One way to rule this out is check the fuel bowl for fuel b4 and while cranking. If no fuel fill the bowl up and if it starts replace the.pump. Replacement Cost $125-320

Common Problem #5
overheating. This could be anything related to coolant. Radiator, thermo, waterpump, or bad coolant. Cost for thermo could be $12-30. That's mainly the only issue or waterpump. $120-250 for one of those. Both are fairly easy

Common problem #6 Icp sensor. Causes the truck to run but cut in and out and really roughly throttle it colander often die on you and or leave you stranded. Cost $65-167
Easy to do

ADDED BY: bigfuel
Common Problem #7
Hissing from the dash when on "Max A/C" or "Defrost" selection is made on the Climate Control Selector. Open the hood and look to the back left (as you are looking and the motor) of the Engine Bay. Near the firewall and right fender there is a vent blending door actuated by a white (factory) 1/8" vacuum line. Inspect for dry/cracking/broken vacuum line and replace. Hissing under the dash will go away. Fix: easy Cost: $10


ADDED BY: madpogue
Common no-start #3 -
Fuel heater - shorts out and blows maxifuse #22, disabling the PCM. Disconnect the fuel heater, replace fuse, re-try start. Replacement cost $3 (?) for the fuse (always carry spare fuses, including maxifuses, in the glove box)

Common hard-start, no-start #4 :
Glow plugs Usual tests for GP relay function, UVCH continuity, resistance of the glow plugs. Replacement cost - depends on what's found to be defective

Common cold-weather start issue -
block heater. Usually it's just the cord, not the heater itself. Test with an ohmmeter / continuity tester. Replacement cost, $20-30 for a generic cord that fits our heaters, avail at NAPA

Common Problem owner neglect -
Coolant SCA maintenance. SCA degredation results eventually in cavitation. Repair cost - you don't want to know (engine replacement). Prevention cost - $20-ish for a bottle of SCA and some test strips if coolant is still fresh, $100+ for complete coolant flush

Common Problem start / driveability issue -
Clutch linkage/hydraulics issues. Weak hydraulics, or worn pedal box bushings, or worn lever arm / eyelet bushing. Extreme eyelet bushing wear can lead to the eyelet expanding (ovalizing). Repair/replacement cost - $120-150 for the hydraulics (complete pre-bled system), $20 (?) for the pedal box bushings (dealer), $5 for the "cheap" arm/eyelet bushing repair (brass tubing + drill stop collar), $20 (?) for the "fancy" arm/eyelet bushing repair (eBay Heim joint)

"Diagnostic" note to add to the IDM item - remove IDM and shake it, listen for water sloshing. Replace if water is heard.

Common problem 5 speed manual :
bushing in pedal arm wears out, causing slack in pedal and grinding of gears. Easy fix remove brake/clutch pedal assembly and. Knock out worn out stuff on clutch arm. Take a 1/2" drill bit and.drill out the hole, take a long 1/2 bolt and.nut.with 20 or so washers put them thru each hole and tighten them sdown till its solid. Done.
Cost. $15 parts from home depot
 
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#2 ·
Common no-start #1A - Fuel heater - shorts out and blows maxifuse #22, disabling the PCM. Disconnect the fuel heater, replace fuse, re-try start. Replacement cost $3 (?) for the fuse (always carry spare fuses, including maxifuses, in the glove box)

Common hard-start / no-start - glow plugs - Usual tests for GP relay function, UVCH continuity, resistance of the glow plugs. Replacement cost - depends on what's found to be defective

Common cold-weather start issue - block heater. Usually it's just the cord, not the heater itself. Test with an ohmmeter / continuity tester. Replacement cost, $20-30 for a generic cord that fits our heaters, avail at NAPA

Common previous owner neglect - Coolant SCA maintenance. SCA degredation results eventually in cavitation. Repair cost - you don't want to know (engine replacement). Prevention cost - $20-ish for a bottle of SCA and some test strips if coolant is still fresh, $100+ for complete coolant flush

Common start / driveability issue - Clutch linkage/hydraulics issues. Weak hydraulics, or worn pedal box bushings, or worn lever arm / eyelet bushing. Extreme eyelet bushing wear can lead to the eyelet expanding (ovalizing). Repair/replacement cost - $120-150 for the hydraulics (complete pre-bled system), $20 (?) for the pedal box bushings (dealer), $5 for the "cheap" arm/eyelet bushing repair (brass tubing + drill stop collar), $20 (?) for the "fancy" arm/eyelet bushing repair (eBay Heim joint)

"Diagnostic" note to add to the IDM item - remove IDM and shake it, listen for water sloshing. Replace if water is heard.
 
#4 ·
I like more descriptions saves time for people searching.

Common problem 5 speed manual : bushing in pedal arm wears out, causing slack in pedal and grinding of gears. Easy fix remove brake/clutch pedal assembly and. Knock out worn out stuff on clutch arm. Take a 1/2" drill bit and.drill out the hole, take a long 1/2 bolt and.nut.with 20 or so washers put them thru each hole and tighten them sdown till its solid. Done.
Cost. $15 parts from home depot
 
#5 ·
this should be a sticky. very helpful.
 
#7 ·
#1) Good idea for a thread. Should keep editing your first post to be clear, concise and easy to read as guys add to the list so people don't have to decipher the whole thread. Know what I mean? Could put the contributor's name at the end of each item so that credit is given where it's due.

#2) TACH BOUNCE HAS ABSOLUTELY NOTHING TO DO WITH WHETHER OR NOT A CPS IS FUNCTIONING/FUNCTIONING PROPERLY :doh:

BUY A SPARE CPS AND A 10MM WRENCH. PUT THEM IN YOUR GLOVEBOX. IF YOUR TRUCK ACTS UP IN ANY WAY SHAPE OR FORM, CHANGE THE CPS BEFORE YOU DO A DANG THING ELSE. THEY CAN BE RESPONSIBLE FOR EVERY SYMPTOM A 7.3 PSD CAN THROW.

Yeah that's right. Capital letters. Deal with it lol.
 
#8 ·
#1) Good idea for a thread. Should keep editing your first post to be clear, concise and easy to read as guys add to the list so people don't have to decipher the whole thread. Know what I mean? Could put the contributor's name at the end of each item so that credit is given where it's due.
Agreed, as long as they're not in all caps.....

#2) TACH BOUNCE HAS ABSOLUTELY NOTHING TO DO WITH WHETHER OR NOT A CPS IS FUNCTIONING/FUNCTIONING PROPERLY :doh:

BUY A SPARE CPS AND A 10MM WRENCH. PUT THEM IN YOUR GLOVEBOX. IF YOUR TRUCK ACTS UP IN ANY WAY SHAPE OR FORM, CHANGE THE CPS BEFORE YOU DO A DANG THING ELSE. THEY CAN BE RESPONSIBLE FOR EVERY SYMPTOM A 7.3 PSD CAN THROW.
So, when the EBPV closes when it shouldn't and hisses like a snake, or the fuel heater shorts out and you get no WTS light, or when the oil gets low and can't feed the HPOP and no oil pressure builds, or the IDM fills up with water, or the ICP sensor flakes out, or the glow plug relay burns to a crisp, the first thing you should do is reach into one of the harder-to-reach places on the engine and swap out the CPS?

Okay, granted, tach movement does not rule out a CPS problem. But to say it has NOTHING to do with CPS operation is just plain false. A better way to express it would be -- if the tach does _not_ move while your cranking it, and you've eliminated the fuel heater / fuse #22 issue, prime suspect is the CPS.
 
#9 ·
Updated. ill add them as they come along. theres not many though. i wont post duplicate problems.
 
#12 ·
To spartan. My hubs have acted up like that. Pull them apart & clean them up good, lightly but thouroughly cover in axle grease. If you put too much axle grease in,they wont function right. Once, out on the trail, i just pulled them and shot wd40 in and it helped. I think it helped make the grease ,loosen up.
 
#14 ·
#16 ·
I have yet to find an answer to what my problem is I've got a 99 f350 psd 6speed changed the oil the other day oil pan still looks brand new but large chunks of rusted metal bout the size of a pea came out with the old oil and now the truck is running twice a bad no power I'm getting a hissing noise even after it's warmed up and a cackling noise I can't explain at all speeds and rpms even at idle in neutral and seems to do it even worse going into a turn left or right extremely rough idle when cold will give you a headache it's so rough any thoughts or ideas???
 
#17 ·
You might be better to start a thread in the 99-02 forum I would pull the pan and inspect the inside and pump pickup/ screen, clean and replace as needed. when you turn the steering pump is placing a load on an already poor running engine so that can compound the problem.
 
G
#19 ·
Frustrated

Need some help! My 97 will start in cold weather, but when I start to drive its seems as if it is struggling for air and produces a much louder sound under the hood. I have checked connections both air and electrical and could not locate any obvious issues under the hood. Air filter is new and I recently had the glow plugs replaced and pcm replaced. I only encounter this problem in cold temperatures 45 and below and while driving. The sound and rough running will decrease if I increase my speed, but it will return as the speed is reduced. When in park or stopped I don't encounter the problem.

Frustrated
 
#21 ·
Need some help! My 97 will start in cold weather, but when I start to drive its seems as if it is struggling for air and produces a much louder sound under the hood. I have checked connections both air and electrical and could not locate any obvious issues under the hood. Air filter is new and I recently had the glow plugs replaced and pcm replaced. I only encounter this problem in cold temperatures 45 and below and while driving. The sound and rough running will decrease if I increase my speed, but it will return as the speed is reduced. When in park or stopped I don't encounter the problem.

Frustrated
sounds like its your ebpv closing for faster warm ups. once the truck it up to temp does it still do it?
 
#20 ·
This is probably not the thread to ask questions like this. It sounds like your EBPV is functioning as it should. In cold weather the valve closes to supposedly warm up the engine quicker. Once your engine warms up I'll bet the noise goes away. Most guys just unplug it, the connection is found near the turbo pedestal on the drivers side. Even in cold climes unplugged seems to make little difference other than an annoying noise and doggy acceleration till it opend back up again.

There are many threads on this issue.
 
#24 ·
if having cold weather hard start issues and glowplugs are getting voltage and ohm out ok i have found that the glow plugs are not heating from the tip and instead about half inch up the tip, remove a few glow plugs and check them on bench with a good battery. observe where it starts to glow and it should start at tip and move upward. compare it to a new motorcraft one. when the glow plug is in the engine it only sticks into the combustion chamber about 9/16 of an inch so when it heats up midway up the tip it is not putting the heat in the combustion chamber. this problem usually causes harder starts as temp gets really cold. also be careful when checking on bench as they become hot very quick and only need about 10 seconds to observe hope this helps someone
 
#26 ·
ok guys need some help asap if possible on my 97 i pulled a couple codes and come to find out its the cps and icp i calle d the guys at the international place and he asked when my truck was build and it was 10/97 he needed the engine serial # but didnt have it and have not called him back he said there was a couple styles of icp sensors to get for it and for aound 200-250 does anybody know what style it would take and which icp and cps would be the best ones thank guys
 
#29 ·
Don't know if its been posted yet- ABS light on dash and torque converter sporadically engaging and disengaging... Speed sensor on rear diff was bad..

I dont know if this is a problem that anyone else has had but it seemed strange to me.
 
#30 ·
I have that same problem and have been trying to figure it out, it will come on out of no where and then it will just decide to go off.


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