How To Change a HEUI Pump. Cat C7, 3126, and C9

This video describes everything needed to change a Cat HEUI pump and what special tooling and techniques are needed to change it. Inspection of the pump is also discussed for possible debris in the Injectors. Questions can be left in the comments. Did this video help you save time or money? @AdeptApe on Venmo or [e-mail] on PayPal for donations, thank you so much for supporting the channel!

[@twojs27]

N thanks for all that you do on youtube to help us out... awesome

[@arshingamini3025]

Jim McMahon inn N Injection actuation per Ensure

[@gabrielocampo2265]

Saved my day, Thank you!🫡

[@Olive-oilien]

Great great great videos! Thank you for what you do

[@richiebledsoe1006]

Always great info totally appreciate your knowledge man!

[@chrischupailo9956]

You do not need to remove the air compressor to replace the line. All you need to do is unbolt the power steering pump from the back of the air compressor (leave the p/s lines on) then all you do is remove the back side it's held by 4 nuts (13mm wrench) then you have access to the 2 Allen head bolts that bolt the line to the block. Then you replace the O-ring on the block and reinstall

[@C.O.SBurpees]

chris chupailo I had to replaced that oil line yesterday and I saw your comment and tried it out, it really helped out alot man instead of taking the whole compressor out just the power steering pump and the rear side of the compressor was removed made life alot easier thanks

[@wazza33racer]

makes sense to remove/replace the compressor and oil line when doing the pump anyway.

[@SteveXNYC]

The oil accumulator on the HEUI pump hold approximately 3000-3500psi of oil pressure to fire the diesel injector during cracking of the engine at startup. Hard start will occur if the accumulator can not maintain 3000-3500psi.

[@jimmyjaan1493]

Nice information

[@rickl6697]

Josh, the head on that new Heui pump looked cracked on the front (above the separation of the head and case), where your left hand is holding it. ??

[@davetuttle9701]

Great videos! I'd love to see a C7S Acert walk around and regen system diag and explanation, the common rail C7S.

[@1HSYURIDIA]

What's the trouble shoot for this ? Why this pump had to be replaced what's the simthoms???

[@1HSYURIDIA]

👍

[@miketh33]

such a pro!!!

[@AdeptApe]

Thank you sir.

[@jasonkobbe4676]

yeah great videos..their isnt much diesel stuff like this on youtube im glad i found your channel

[@AdeptApe]

Thank you sir. I try to put up a video a week for my subscribers. Please subscribe. Thanks for commenting.

[@ameerbaloch4125]

Very good

[@asgrowler]

really appreciate videos,, I have a c7 cat , and have No Fuel pressure , can you help

[@Razz-es9qw]

Replacing the injectors is only necessary if that solenoid itself fails and leaves metal shavings around the solenoid? Can contamination be seen through some of oil lines going into the cylinder head? Thank you for the informative video...

[@jorgeherrera2275]

Does the high pressure supply line to the head have any O rings or just the ones that sit on the connectors? If you could help please I’m in desperate mode I have had issues with this for about a year

[@ethanpaul7668]

How about a video of the 3126 with the bolts on the back of the heui pump

[@debescuadro8052]

Hi, Can i ask about C9 engine, If we change new injector, It need also re-incoding the injector? Thnks for d answer plz,,,

[@Backwater-wanderer]

Could you tell me where the fuel pressure regulator is on this engine?

[@elitetimberservices]

Can you use the other style huei pump that's available. Does it matter?

[@WorldsOkayestFarmer]

*Great video man! I watch a lot of them because I run two trucks with these engines. Just had a pump go out. Thanks a lot* #WorldsOkayestFarmer

[@zanestinnett6826]

I have a 3406b. The huei pump? Is leaking oil. Can I rebuild it myself

[@jorgeherrera2275]

I just replaced it but now I’m loosing oil through the blow by could it be related to the heui pump or any other suggestions highly appreciate it

[@josephchurey1909]

My parents have a 2002 frieghtliner motor home with a 330hp cat 3126 every was fine with it until my dad fired it up the other day it ran for a minute and then shut off the fuel filter I drained the cycled the key a few times but it will not fill back up with diesel but fired up with a tiny bit of starting fluid any recommendations

[@kayliabanton3488]

Why would be the reason for changing the HEUI PUMP

[@gaspargarcia4177]

Im about to change diesel filter can you tell me how to prime it or es electronic primed the engine is a cat 7.2 C7 hope you can help me!

[@kenherrod]

Hi. I have a 05 C7 not getting fuel. Ran great before it got 20 below a few weeks ago. Changed filters. Did not help. Ordered new fuel regulator. They sent the wrong one. Just took out the old one and tried to start. No fuel is coming out of the hole. Fuel gauge is showing 0 psi. Time for a huie pump or is there something else i can try first? Thanks for your help.

[@toledomachinery2189]

Good evening, I have a cat 140K year 2010, he is blowing white smoke through the engine breather, and he reissued valve guides, engine block, compressor, he changed rings, checked the engine liners. Bearings, even changed oil pump and pressure pump, but the problem persists, white smoke is still coming out of the engine oil nozzle. What I can do, changed almost everything, I only need to see the turbo, which advises me or which believes the problem.

[@richardashman6990]

Do you have a video about replacing the flexible oil line going to the HUEI pump? The replacement line is a rigid steel tube assembly.

[@motox4150]

I think it has a filter as well.

[@chriszorbas9415]

Hey great videos can't thank you enough! I have a c7 in a f750 truck runs great until the temp gets close to 180 then the truck struggles to build/jumps the rpms only when driving and idles a little shaky could this be a cause of the heui pump?

[@cameronward7137]

Long shot but I have a c7 that looses fuel prime if it sits more than a day. What could this be??????

[@datowing]

thank you for your reply when you open up the lines and flush the system you will be flushing out the oil side will it be metal in the return lines for the fuel tank I'm trying to figure this thing out I am a gas mechanic this is all new to me thanks

[@AdeptApe]

+duane addison You are only flushing the HEUI oil system, but the fuel system. You are basically blowing out the old oil and little tiny pieces of metal so it should pour out the back HEUI plug in the head and go into the cylinders. You'll have to evacuate the cylinders after which should remove nearly all the fluid and debris from the cylinders.

[@matthewsandgren7598]

So I have a code 63 once in awhile what's ur opinion on changing the transfer pump on the back of huie pump?

[@bagmann89]

I need help installed new injectors, fuel rail filters lines etc and still wont start

[@QuantumRift]

This is great! Man, your videos are great. The HPOP on my 3126 diesel has a corroded case...I'll be into that job sooner or later. "Adept", my question is this: Is it possible to find JUST the metal DOME for my 1996 3126 HPOP? I knocked off the rust and wire brushed it, and hit it with some Rusteoleum Rust Restore paint, but I'm thinking sooner or later that's gotta be replaced.....I can't see to find just that part.... the "DOME" for the 96 3126 HPOP.

[@AdeptApe]

+QuantumRift I've never heard of changing just the dome on the HEUI pumps. If you wanted to the best bet would be a junkyard, but Cats usually get sold as an engine. Cat doesn't sell just that part though.

[@joseamezola4345]

Okay I have a question I would appreciate your help I have a c7 in a 07 c7500 it is leaking oil from between the fuel transfer pump and the huei pump what is the process to stop it is there an o ring that seals it and do I need the fuel transfer pump removal tool from cat thank you for any help you can provide me

[@zxstream]

I have a C7 in our RV that is now popping the CEL "94-1 Low Fuel Pressure Warning (63)". Does this sound like my pump is going bad? If so, how would I change it in a pusher Freightliner chassis? I'm pretty mechanically inclined but it sure is tight in there! Help from all is welcome please!

[@primitivoortega265]

I have this code actuation pressure output fault ?????

[@johnstoker1944]

If you do this repair, is it necessary to change the injectors too?

[@kevinolson3030]

I replaced the transfer pump back of heui pump due to an oil leak on cat c7. Now I have an oil leak on the front part of the heui pump. Was wondering if the gasket is able to be replaced or need a new heui pump. Thanks

[@kilroyjohnson6533]

Why is my oil not getting oil to the rockers and not starting?

[@jerryw4458]

I'm trying to purchase a 2005 motorhome with a 350hp C7. This whole HEUI pump has got me scared. Is this a great concern?

[@imran3055]

Can we open IAP control valve. For replacement???

[@ralphbaker9666]

Hi Adept Ape, I have a 3126B 8YL49553 330hp in a motorhome we had a lighting strike close to our house and ever since I can't get the rv started. The coach was plugged into the house for power like it always is. A cat tech guy came out and hooked directly into the ecm and said it was dead would not communicate with his computer. I ordered a rebuilt one from a company in Texas with life time warranty hooked it up and nothing same as old one. Have a pressure gauge hooked up to the high pressure rail and all I get is 200 psi, I know I need at least 850 psi to get it to fire. checked the fuse and ground and cleaned both, question is did i fry the new ecm is there some way to check wiring to find a short or what do i do. On a side note the lighting strike also took out the circuit board on the water heater. Help thanks Ralph

[@Davobeff]

What powers and grounds do you have into the J2 plug on the ecm?

[@marcoknight4154]

Hey Ape!! Good tips you give here on your videos!! But i still have an issue i got this RV with a Cat 3126 and it wont start just cranks the tach does move and the oil press does move too. A previous tech says the fuel injector pressure is 200. What can you suggest it is?

[@chichon1188]

Hey brother! Love you videos I’ve being watching all of them, now I have a question about the heui pump I remove the lift pump of the heui and I didn’t use the so call special bolt and all my springs and stuff I. The other side came out, I get to put it together but I heard that once all the springs and parts come out the pump would not run the same and I have to get a new heui pump?

[@TheGeneral100]

Hi What's the voltage I should read going to the fuel pump? I'm only getting 10 volts crank but won't start

[@piper4me584]

I'm about to purchase a 2005 Freightliner sportchassis with a C7 cat motor. Under 100k and lots of good maintenance and service records. My question is I read so many issues with the heui pump dumping metal into the fuel system and causing injector damage and replacement. Why hasn't anyone added a high pressure inline fuel filter from the heui to the fuel rail ? Is that even possible ? Very new to Cats, all my toys have DD 6-71TI's. Great video and thank you.

[@michaildziuma9502]

I have 3126 just changed Heui pump truck will start now but it will cut off in 2/3 min Need help please

[@myinfo3406]

did this only once took about 2 months....lol

[@ericbarkan1]

I have a question. I have a 3126 in my bus that has this same Heui pump. The rubber feed line is leaking a little (seeping). Is this something I need to address immediately, or is it ok to run it for bit while I gather parts?

[@MarkJohnson-oo3dx]

3116 fuel pump does it have to be timing

[@bpatel4434]

Hi adept , I have c7 -190hp-freightliner straight 5ton truck . Problem - diesel in oil and low oil pressure Cat guys changed o rigs of injectors and now they are changing transfer pump . I am not getting any code. Cat dealer guys also confused about this dilution. Plz advise Thanks

[@rickl6697]

Can you replace a square head heui pump with the round head heui pump. I believe in a different video you said the round pump had less problems and you could replace the driver separately from the rest of the pump for a lot less money. I have a rv with a 330hp 3126e. Thanks

[@drewwetterling6753]

I'm doing my first rn on a motor home it's terrible

[@fourwayengineering5827]

hi sir hope you well thanks for making very good videos its a really big help . i like to know if you have made the video to replace the common rail fuel pump on C7S . please send me the link or just one qustion about the common rail fuel pump have timming or not ? thanks

[@rickl6697]

Josh, at 1:11 mark is that the upgraded high pressure oil supply line(solid steel vs. steel braided hose) you talked about upgrading in the get to know your 3126 video. Thanks. Trying to tell if our 3126e hose has been changed.

[@miftachularifin7751]

Hi Adept, can you explain the difference between C7 and C9 injectors? and can the c9 injector be used in a c7 engine?

[@richs5731]

I have a 2003 fl 60 with a 3126 E motor with a C 7 pump not a round top is this a better pump And can you add a jake brake to this motor

[@boywillie574]

I put a 3208 cat in a 68 international scout 800

[@ttompetty]

front housing cracked slightly, that isnt important for a good seal? at 4:53 i see small crack

[@AdeptApe]

+Art Huge I had to see what your talking about, that was probably a casting line, not an actual crack. That whole housing is filled with oil, so if it was an actual crack it would leak oil everywhere.

[@ricojohnson4230]

Are you still replying to question ⁉️

[@frankscherb3683]

Hi Adept Ape, I have just found your channel. At the moment I have a problem with a Cat 3126 engine mounted in a Claas combine. The oil line to the top of the motor was pulled out of the housing of the pump. The motor stopped immediately and some oil got out. We are still waiting for a new pump, because I am from Germany and nobody here has a new one. We had to order it from the US and are still waiting since one week... Just some questions: Do you think, the engine can have some damage? The engine has 2000 working hours. Do you have some experience whether it is normal with this age? Many thanks for any reply.

[@adamh6507]

Can someone tell me the size of the opening on that tool? Trying to locate one for an FMTV in Germany, it's an impossible task. Need to fabricate.

[@melbreki3388]

I enjoyed the video and learned a lot, thank you. Could you tell me the part number for the sealing O ring on the pump. I ordered a pump but it did not come with the O ring

[@shreeequipmens573]

Where can we purchase c9 engine heui pumps

[@QRS365]

at 4:53 head appears to be cracked???

[@rockyviewwatchdog7665]

Hello AA, It's Mike from the Jpaydirt channel. We are considering switching out the old fuel injection system on our current build called old kenny with a 1693 in it. We would like to switch it to a high pressure common rail system and wanted your opinion. Thank You, Mike

[@AERSLLC]

word of advice make sure to remove add thread locker and re-torque the drive gear nut. have found them lose or to become lose after a few hours of running. also had some come in with a lose nut on ones just replaced by freightliner.

[@AdeptApe]

I have seen a couple with that happen. What ft lb do you torque the nut to?

[@AERSLLC]

Adept Ape normally 125ft/lbs but now I just use a 1/2 impact wrench.

[@rcmartinfarm3512]

My Sencer on top of heui pump is lose and has a slow oil leaking around it is that a problem ?

[@mattfrank5482]

Is the valve on top replacable . do they go bad?

[@Pawinterservices]

I have a 2000 F750 with 3126, truck recently started to lose power after 30 minutes of use and reduce to 10mph with CEL. Changed high pressure oil sensor, still no luck, mechanic says high pressure oil pump should be changed, seem like a logical next step? I should mention shutting truck off and restarting clears CEL and problem goes away for 5-15 minutes until it loses power again, seems to happen at lower speeds not highway cruising. Thanks

[@AdeptApe]

+PA Winter Services Before you start changing parts, what is the check engine light? If you have injection actuation pressure faults it might be the pump, but it could also be leaking injector seals.

[@darrelldoward8761]

Adept Ape t

[@lekkousa]

Loved seeing the 3208 in the Suburban!

[@AdeptApe]

Thought a few people would find it enjoyable.

[@darrelldoward5998]

Your videos are very good thanks you. I would like to know what I need to troubleshoot my engine? I have a 3126 installed in my boat and it is loosing power. Thanks Darrell

[@enginemaster01]

make sure and have new lines when doing this procedure. and this is easy. try doing on a c9 marine engine

[@jhonariasflorez3306]

El vídeo se ve bueno.... Pero para las personas que no sabemos inglés sería bueno que viniera subtitulado

[@piotrfilipczuk8001]

Hi. I have a C7 engine over an overhaul, a new head, an original CAT (90,000 miles ago), the diesel goes to the oil. I changed the o-rings on injections, I changed the diesel pump, and nothing. I still have the same problem.No smoke, power is good, the engine works equally. Where is the problem. PLEASE HELP

[@bpatel4434]

Piotr Filipczuk Did u found problem cause? I have same problem like u and now i m changing trasfer pump Plz advice

[@LuizHenrique-vc2cr]

Does this system make the engine super warm up?

[@AdeptApe]

+Luiz Henrique No, it really doesn't contribute to an overheating engine. It just powers the injectors.

[@hectorgallegos5055]

Hey man got a quick question I got a c7 not firing all injector seals are leaking on the the top .. replaced all orings on all injectors tourque to spec and still leaking .not allowing oil pressure to build up and fire ..could I have a bad head ? Or maybe the bolts are too stretch 🤔,and not getting the right torque ?

[@treychastain4686]

On some models the injectors do leak excess pressure of out a weep hole.

[@podlfksduesfe2539]

Great video man!, love all these videos on CAT engines gives me a better clear knowledge.

[@AdeptApe]

Thank you, I'm trying to slowly build a KZbin based repair base for Cat engines.

[@podlfksduesfe2539]

+Adept Ape well man keep those videos coming we all enjoy them

[@maxxtech8532]

Is that solenoid inside the pump like an IPR valve? Seems like it has the same function.

[@edwinaragon6517]

Buenas tengo problemas con un motor cat 3126 no me enciende en las mañana tengo que echarle éter

[@billhowe4863]

Is that fitting an stc?

[@harpreetsingh-or6lm]

Sir please give your email. Sometimes diesel mix with oil

[@dronez9047]

Ape I love your videos, starting a Diesel Fitting apprenticeship soon and all these videos are an unexplainable amount of knowledge! Thank you :)

[@AdeptApe]

+Dronez Thanks for watching them

[@zanestinnett6826]

​@AdeptApe need help. I have a 3406b the fuel pump is leaking oil from the back. Can i rebuild it myself

[@gabrieltrejo1213]

I have a 2005 freighliner m2 with a c7 , check engine light comes on with a injector control pressure, I suspect of a bad huei pump, can anybody help diagnosing this problem?

[@ojongagodfrey7201]

thx for the lecture sir, i also have a problem with one of our wheelerloader 996h, showing three erro ,engine oil pressure,coolant temp,air flow, and engine has no power, pliz advice thx

[@omar19936]

Hey Adept so when you connect the et to a c7 or c9 to check the heui injectors, how does the computer tell you that an injector is bad ? what parameters does the et rely on to decide if an injector is bad? i mean the harness on the injector is only to actuate the solenoid, so the diagnostic computer can only tell you of an injector harness is bad or open, but it cant tell you if an injector is weak or worn out..right? thanks a bunch mate!

[@AdeptApe]

It is going to be hard to explain in a comment section, if you have seen my cylinder cutout test video it does explain how it works. The ECM determines how much fuel each injector uses. So when you do a cylinder cutout test the ECM sets the RPM to a set speed. Then if you cut a cylinder out, the ECM has to increase the amount of fuel to the other five cylinders so you'll see an increase in the fuel position. Now let's say you cut out a cylinder that is dead, well since that cylinder wasn't helping the engine run, you wouldn't see an increase in the fuel position to the other cylinders to keep the engine rpm at the same level, so basically you are seeing which cylinders aren't contributing to the engine running. Hope that helps. I'll try to do a video better explaining it.

[@datowing]

hello how are you I would like to know where could I find the procedures to flush the C7 engine when it has metal in the injectors and Heui pump I have the replacement parts I just need to know what should I do to flush everything out before I install them thank you I looked for your link I could not find it

[@AdeptApe]

+duane addison Just remove all the injectors and one of the HEUI rail plugs and flush it out with brake clean or solvent. Then evac the cylinders.

[@haleymatson8794]

I replaced the entire top of the engine. On a 2004 c7 cat engine Valves etc. Im getting power to the cab but not too the starter. Replaced injetors o rings. But it wont turn over what could it be

[@AdeptApe]

+Haley Matson Did you suck the oil out of the cylinders after you pulled the injectors?

[@SteveKluver]

Thanks for this video! A big help. Especially the part about telling us that this unit is not timed. A nice little fun treat there at the end too! I am going to look at some of your other videos now. I'm hoping to possibly learn more about the engine/fuel injection difference between say a 190 HP 3126E, and a 330 HP engine. I have one Truck with a bad 210 HP 3126B (70 pin), and I'm hoping I can more or less easily swap in a two year newer (70 pin) 3126E, of 300 or (EMS) 330 HP. I'd sure love to learn more about how Cat gets 800 ft/lb, and 860 ft/lb rating out of the same engine. It seems they are selling a high, and low torque models?

[@AdeptApe]

+Steve Kluver Thank you for watching. The 3126 engine and head are all the same. The differences between a 190 hp and a 330 hp is the pistons, injectors, turbo, and possibly the damper, HEUI pump, or camshaft. Depends on what rating you are looking for. The newer 3126 should fit right in. Just check that the transmission can handle the torque.

[@SteveKluver]

Thank you. I am waiting on a call back from a couple of different dealers now. I must have caught them off guard, as I could hear them over the phone scratching their heads, during my questioning of a 70 pin 'E' easily going into a 70 pin 'B' engine bay : - ) Do you happen to know what the lowest HP rating is, that does have all the right hard parts, but is just cut short a bit, by the ECU tuning? 250HP?

[@AdeptApe]

+Steve Kluver I believe the lowest "high horsepower" is a 250 800 torque, but that is a C7. I'm not 100% on that I'd have to check, the 3126 engines had more variability. If you find one with either 800 or 860 torque then that is the high horsepower build and should be able to be uprated. If you find one send me the serial number and a new message and I can try to look it up and tell you.

[@SteveKluver]

I will do that. Thank you. PM coming your way.

[@AdeptApe]

+Steve Kluver I got your PM, I'll check the serial number for a rating. In the future you can send me emails directly at [e-mail] it is much easier than using the PM feature.

[@boomstickkid]

is the air compressor timed on a c7?

[@dieseltechnician6227]

does the older version heui pump on a cat 3126 require timing before reinstalling or is it the same no timing requirement as the one you installed in this video?

[@AdeptApe]

It isn't timed, you can install it at any point in engine rotation.

[@gilgil5351]

Hi there, i really hope you could help me troubleshoot my 3126. It started by being harder to start once hot, then again it was hot and didn t start a all sometimes run for a few seconds very rough. Now no start and again try s to start like making some effort thats it just like a gas one with fuel pump problem. Do you think it could be fuel pump on this one too? On it it say s reman. Its the round top one. Strange thing is the line runs strait from the tank to the pump without a filter. Its in a freight fl 60. Thanks in advance.

[@tylermott6563]

Did you ever get it figured out? I have a 3126 in a freight FL60. I suspect bad HEUI pump. Code 164-11 according to cat et. Haven’t done any further troubleshooting yet.

[@gilgil5351]

@@tylermott6563 Hi there, yes i did! Like i said there was no inline filter for i dont know what reason... It was a little piece of plastic like an old straw or something like it that found its way all the way up to the fuel pump line connection. Just pulled it out, put an inline filter and its running perfect since then.

[@henshawhench3654]

Great video definitely explain every step

[@ttompetty]

took my 05 cat c7 to cat and they said they swapped the pump, still got codes for inj pressure sensor fault, cat said swap all injectors, truck runs great for 3-5 minutes until warm then derates to 45, loss power,, no smoke, at initial startup.. idles nice,,.. question..i took it to local mechanic with cat programmer, he is a waste money, just says pump bad until i told him cat just swapped it,,how can i make a fuel pressure tester good for what 4000psi? and then how do i make the driver deliver 4000psi without burning itself up or hurting anything else, including me... to test the pump output of course.. i did swap the inj pressure sensor and codes gone but derate and no power still happening.. lastly.. if injectors ARE clogged will i be able to see or test when i get them out to determine that IS the cause?

[@AdeptApe]

+Art Huge A lot going on in that comment so I'll try to answer what I can from there. So you can get very high pressure test hose like a hydraulic line and they make high pressure gauges as well. I've got one that goes up to 8,000 psi. It is scary to use but a HEUI system idle is only at 1200 psi usually. So if the code is gone with the new sensor then maybe you have 2 separate problems going on. You should check the fuel pressure as well. You may have a fuel pressure or other problem and not a HEUI fault. Now I've seen the ECM act weird when they come out of cold mode as well and they won't tell you what is causing it. With no codes my advice would be to check fuel pressure and if it's still running rough do a cylinder cutout test to determine which cylinders are the cause then go from there. I don't know of a way to test those HEUI injectors outside of the engine, but check with a local fuel shop that does injectors and they might know.

[@ttompetty]

ok thanks, cpl last quick ones..1) if im using a needle gauge or led test what would be wrong with checking for injector pulse at the inj wiring,, noone ever says do it and ive done that many times with car fuel inj,, to see if crank/cam sensor readind etc..only using a gauge that would not backfeed power to the driver,,,, 2) how do i trick the inj pressure driver, 3 wire sensor/actuator to give me max psi to force liquid past inj orings,, to test for oring leaks,,and final question,,3) can the derate protection be turned off across the board for all triggers inc no oil pressure

[@collinsampson7868]

Cat 3408

[@geegrim5129]

I have a 3126E in a 2004 motorhome. The HEUI pump looks exactly like the one you refer to as on a C7 engine. Is the 3126E similar to the C7 injection system? I know it's the last motor design before they went to the C7.

[@AdeptApe]

+Gee Grim Yes on some of the latest model 3126 engines they had a C7 style HEUI pump. They should still have the square injectors though and the HEUI systems are the same on both engines.

[@geegrim5129]

I've watched a few of your videos, they're very informative. Thanks for the info.

[@redDmax04]

These videos are great going to leave a donation for you my question got a 98 Peterbilt 330 dump truck with a 3126cat 210hp s/n#1wm13822 230k it will miss under load over 1500rpm only at cruising or pulling a hill while pulling trailer or hauling dirt empty it will miss very little you don't notice it very much taking off from a light is fine till about 35mph then it starts the tach needle jumps around when it's missing any help is very appreciated

[@AdeptApe]

+redDmax04 Hmmm, seems like a load dependent miss. Any check engine lights? If you have a cruise control switch can you try and email me the blink codes.

[@redDmax04]

Code 55 if I recall means no faults I took the truck out for a ride today I t seems the more you step on it When it starts to miss the worst it gets