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99 7.3l running like crap

10K views 22 replies 6 participants last post by  banditman 
#1 ·
I went and started my 99 this morning and it started but just sounded like crap and has no power. It kind of sounds like it is missing on some of the cylinders. Any idea what might be wrong? I am two hours from the nearest scan tool that will read one of these trucks so thats not really an option. Where should i start?
 
#3 · (Edited)
A scanner realy helps to diagnose the issue. Is there a CEL on? I would plug in the block heater for a couple hours and then fire it off and see how it runs. If its a rpugh running/ missing when cold that gets better as it warms up and you have no CEL it can be an injector issue. A buzz test would be nice when cold. Other than that pull the valve covers and measure armature gap on the injectors. The reason there is no cel if an injector has a mechanical issue is there is no misfire monitor on these PCMs. The IDM just detects continuity. It just fires a solenoid coil. What ever action happens under the solenoid is mechanical and the IDM has no way to detect if the poppet valve actuates.
 
#4 ·
How much fuel do you have. Pickup foot broken in the tank and or clogged mixing chamber screens
time for the hutch mod


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#5 ·
Hutch mod

This is my version of the hutch mod to do away with the horrible unserviceable factory pickup screens in the tank. This is called a mixing chamber what it does is mix hot airy return fuel back into the suction feed going back to the motor poor design on fords part. When the screens get clogged the truck with studder and white smoke and the pickup foot will deteriorate over time and break off and cause the truck to catch air causing all kind of symptoms that people will tell you bad turbo, injectors, uvhc, and on and on when it's rather simple.

List of things needed

Napa 4770 filter housing

3/8 brass barb fittings for the fuel filter housing for the inlet and outlet.

Baldwin fuel filter bf1212

Some bolts and nuts to mount it

About 15' of 3/8 blue fuel line

Some hose clamps to fit over hose about 8 of them

A set of quick disconnect fuel line tools

Patience

Basic socket set / cordless impact works wonders

Jack

Tape measure

Hammer

4lb sledge

Big flathead

First run tank down to under a 1/4 tank

Remove the 3 small bolts in the fuel cap door that hold the filler neck on the bed, behind that is a hose clamp to a tab on the filler neck tube remove that

The tank straps are simple undo the single bolt on each strap on the inside the straps not the outside the outside are where the straps hinge down. (If you have a skid plate has to be removed) the bolts are much easier if you have straight exhaust because the factory muffler gets in the way

You should then be able to lower the tank down by laying under it and doing it by hand I find this much easier than dealing with jacks. You may have to fish the filler neck and all around the frame slightly. I never remove the tank all the way unless the truck is 2wd and low.

Disconnect the sending unit wires. Then use the fuel line disconnect tools to undo the two fuel lines on top the sending unit.
Now take the hammer and flathead or a piece of 1" square aluminum tubing works good and hammer off the big plastic nut that holds the sending unit in the tank.

Nut off now pull the sending unit out the tank. Now take the 4lb sledge and beat the hell out of the white plastic mixing chamber until it brakes off the suction and return lines. ( now look at the two small screen tubes at how clogged they are) and if your pickup foot wasn't on the sending unit it's broke off in the tank.

Now take a piece of the 3/8 fuel hose about 18" in length and clamp onto the smaller pipe that's the return line so that it goes to the opposite end of the tank.
Now cut a piece of hose about 6-8" in length and cut one end in v formation then clamp the hose onto the big straight line on the sending unit this is the suction/feed line. Measure from the sending unit top down 13 3/4" from the top the sending unit to the bottom of the piece of v cut hose this will ensure the pickup is right on the bottom of the tank and the v will allow it to pickup good amounts of fuel. I have done over a dozen kits this way with no issues.

Now you can reinstall the sending unit. Here is where the patience comes in the big plastic nut that holds the sending unit into place is a pain in the *** sometimes it will go on in seconds or minutes and other times it will fight you for a hour cross threading.

Prepare the filter housing by plugging one inlet and one outlet and install the 3/8 barb fittings.
Now mount the filter housing between the fuel pump and the tank somewhere easy to access for you just watch for the lines in the frame when drilling holes for bolts I have found just 2 of the bolts sufficient to hold it in place and I have used one factory hole in the frame. You can make a bracket to sandwich the frame to mount the filter inside the frame but I have been mounting them outside the frame with no issues.
I also have mine mounted to the cab with self tapping bolts for 3 years now.

After mounting now run a piece of hose from the suction on top the tank sending unit to the back of the filter housing inlet. It's tough to get the hose over the factory suction on the sending unit I find a little dawn and a pair of pliers the lightly twist and I push it on works great. Hose clamp it in place. The factory suction line from the back of the fuel pump to the sending unit is no longer used. Also hook the factory return line back to the top the tank. You can now put the tank back up.

Now run a 3/8 hose from the inlet on the filter housing to the back of the fuel pump that's under the drivers door inside the frame.

Now just fill your filter up with diesel and cycle the key about 10 times to work any air out the system and fire up the beast.

The filters are readily accessible at any auto parts store for around $10 bucks and the factory $30 filter I have let go as long as a year and checked it to find it still looked like new due to the extra filter.

This is hands down the best mod to do to the 99-03 7.3s the factory design is poor and crappy. This mod with clean the idle up give you better throttle response and aid in any more upgrades you do and allow more fuel to flow easier.


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#6 ·
Thanks for the help. Yeah i no i need to do this to the tank i run out of fuel at about a 1/4 tank. I left the truck plugged in all morning and tried to start it again and same issue runs like crap barely can move. Do the 99s have a crank sensor i had a 96 that would go bad all the time?
 
#8 ·
Yep if your running out of fuel at 1/4 tank that's the problem. It's probably white smoking no power like a horrible fuel knock I have had 4 superdutys so far and everyone has had either a clogged mixing chamber screens or pickup foot broke most the time both. I have done over 15 kits now for me and friends it's one of the best things to do to a 7.3 first


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#10 ·
How many miles do you have. My first superduty 7.3 I was having that issue and I read about the broken pickup foot so I filled the tank up and same issue so I dropped the tank and put a new pickup foot on not realizing the screens inside the crap mixing chamber were clogged and had to drop the tank again. It won't hurt to drop it and do the hutch mod don't just drop it and clean the screens it's not worth it.


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#11 ·
I got the torque pro app today and it says there is no trouble codes stored in the ecu so i am leaning towards that it has got to be problems with the tank. Not really sure though you have to use pids to monitor these trucks so im not sure what the info means when you test it but it seems like everything is working.
 
#12 · (Edited)
Torque will not read codes. You said you had a CEL. Download Car Gauge Pro and it will pull the codes. I think Forscan also will pull codes. As for testing the fuel system you will need to test fuel pressure with a mechanical gauge. With torque you can look at things like ICP and PW which can help you diagnose the problem.
 
#14 ·
How many miles are on the truck?


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#15 ·
Won't get over 40 shaking like crazy, the idm may cause it but if your running out of fuel already at 1/4 tank then you already have issues in your tank and if you have over 150-200k miles them screens are nasty hadn't pulled one out of over 15 yet that wasn't people would be surprised what issues and it can cause. I like my areo force scan gauge for reading codes clear codes, buzz test, display two sensors, best $250 I spent for monitoring.


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#16 ·
And just so you know my ses light would come on when I would try and drive the truck missing and shaking due to not getting enough fuel and it would go back out. Also you need to make sure the fuel bowl is filling up and the pump on the frame under the drivers door is working


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#17 ·
I got car gauge pro and pulled the codes and this is what i got B1352 body ignition key in circuit failure, b1310 body power door unlock circuit failure, b1217 body horn relay coil circuit failure, p1690 power train waste gate solenoid circuit malfunction, p0381 glow plug / heater indicator circuit, p1316 power train injector circuit / idm codes detected, p1247 power train turbo boost pressure low.
 
#18 ·
Use Car Gauge Pro to do a Buzz test when engine is cold. Listen for mute or muted injectors.
 
#21 ·
Likely a wiring issue. Check and OHM out the #7 injector circuit. Look for chaffed wiring or insulation that has rotted and fallen off.
 
#22 ·
Ever drop the tank and check it. I have had it cause issues that would make you go crazy and it's a simple fix and quick to eliminate that variable for a hours time you can eliminate that as a culprit


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