Great material, thanks. This helped me diagnose a Check Engine Light- code 94 / “limp home” mode activation on an ‘06 C7 in a motorhome. I replaced the fuel pressure regulator and it resolved the issue. Interestingly, it also corrected a light torque load 25-35 mph surge/shuffle condition that the motorhome had since I purchased it about 30K miles ago.

I don't have time or $ to go to school. All I basically can do now is watch your videos.

I love your videos!!! I have a pre acert c-15. I started as a company driver on a Volvo 10 speed then got stuck in several automatics for a couple of years... finally bought a real truck lol W900. I bought it from the original owner (‘03). I have a mechanical background but I’ve never tackled anything like this before. I appreciate your logic. I’ve talked to mechanics who just like to throw parts at it. Ughhhh. Thank you for sharing your wisdom and knowledge!!!!

This fellow is real good... with good intentions... I am learning a lot with gratitude!..

when gears in transfer pump are worn or bone dry it can't pull a vacuum. We used to pressurize the fuel tank about 5psi or less and push the fuel up. Check valves also leak back to tank . I just fixed a Mack 300 it was the check valve in pump on that motor. Excellent work thanks!

Sorry just saw your message. I work full time for the city of buffalo as a mechanic at the highway garage. Then I work part time for johns towing out of Tonawanda ny. Towing and doing road service. Also help out at Beaumans garage in Lockport by basically doing the same thing and doing in shop repairs on cars, light truck's and rigs.

Thanks for the videos. They are extremely helpful for do-it-yourselfers such as myself.

Man, I can't thank this guy enough.

Army mechanic here. C7s and c15s always fuck us when they wont start. We don't always have the tools supplied to troubleshoot so this knowledge is priceless.

We replaced the injector O-rings, transfer pump, injector harnesses, fuel pressure regulator, check valve, did a complete PM, ran the rack, new starter, batteries as well. It ran for a few hours. Ran a bit rough, yet it ran. Next day no start. We already performed the 5 gallon bucket test directly from the pump. Had someone come out and hook up to the round connector under dash. Computer screen read all 6 injectors low voltage. It will start with starter fluid but then dies. No throttle response. New throttle position sensor, timing sensor(on cam) as well. MXS C15 ACERT. Many thanks.

Great videos buddy, I love watching them. We don't do extremely ridiculous repairs where I work, but at least now when driver ask about the system or have in depth trouble shooting questions I can tell them something besides 'I'm not sure' and I will definitely refer people who have questions to your videos. Keep them coming bud!

So Adept Ape i have talked to you once before about my 3126 in my 2002 GMC rollback. So recently i have developed a miss at idle and under acceleration. It has gotten so bad that it takes forever to get up to highway speeds. I went to my local truck repair shop that had the proper computer to talk to my truck. He did a cutout test and at the time the injectors showed no issues and all passed fine but it was just at idle. That weekend i changed both fuel filters, Oil filter, and oil, also did a transmission service and replaced both batteries. Also did a valve cover gasket to get rid of some oil leaks. Checked the injector connections at that time and did not see anything out of the norm. put everything together and the miss is still there.and it gets worse when it gets warmer. There is no fuel or oil in the coolant and there is no oil in the fuel tanks. i did a little research and read about changing the fuel pressure regulator. Changed it with a CAT part and no luck it is still missing. So im at a lost as to what it could be it has no issues with starting it just has the miss please help with anything i could check. I thought about pulling the injectors and checking the O-rings. Or i thought it might be the HEUI pump or the fuel pump on the back. I have the tools to work on this, it is just im 30 years auto tech not diesel. So any help or direction to start will help because having a tow company time is money Thanks again and keep doing the videos I m on the west coast so im the same time as you.

cool. I am up in Buffalo N.Y. I watch alot of your videos over and over so I don't miss anything.

I have a 379 Peterbilt 3406e . I had the engine complete out of frame over haul excluding the injectors and the turbo. Engine performs great when warm. If it has been sitting for a couple of days...when I start the engine up...it performs as if it's starving for fuel...it idles really rough for a couple of minutes with a sort of a cloud of smoke coming out the stacks. With in 3-5 minutes of idling it stops smoking and begins to idle in a normal fashion with missing. When I first took it back to the repair shop and informed the guy the engine was not idling properly and he stated that it should eventually clear up in the very near future and I should add a quart of oil to each fuel tank. this is a problem I did not experience before the out-of-frame. I later returned to the shop and the guy told me I had some fuel lines leaking. It was recommend to change all of the fuel lines. The the shop informed me that it was not the injectors. I am at this point so confused, after sticking $22K into the engine. What do you feel may be the issue here? Please reply. thank you.

Thanks Josh. Great video! Very informative and complete. 👍😎

I love watching your videos! They are so educational and helpful. I’ve learned so much. I have a question about this. I have a Kenworth T800 with a c-13, I started losing power in a stuttering sort of way like fuel filter was clogging up. So I changed out the filter and now it is worse. I can barely move in a parking lot. Worst part is I’m in Kremmling Colorado and there’s no mechanic. I called around and they all say that all they would do is change out the fuel filter. So I’m stuck with no help. Any suggestions on what it could be? Or what I could do myself to maybe get closer to a shop?

I once had a truck that overnight could not be started until the fuel was raised back up to the lift pump because it was running back to tank. Replaced all the braided lines.......even installed a one way valve with no effect. Turned out one of the swivel fittings on the braided hoses was worn and allowing air into the line and as such the diesel was able to run back under gravity into the tank.

thanks for this video!! was pulling my hair out changed all the tank lines and found out from here it was pressure regulator,,,,5 minutes

Amazing videos! Best / Top information ever! Thank you!

Studying for upcoming remote diesel fuel systems class for my associates degree . getting started earlt

What a great job you are doing specially for bigner

Can you make a video of all of your fuel/oil pressure gauges you use for diag? These are the best videos

That is a really nice video bro you explain basically everything my question to you is I have had a couple of c15 they come here for service and they have the 0749 which is a secondary filter put in the primary putting them like that because client ask and they won’t start

Rate your channel bro keep up the work ...... For the big engines you can bypass the primary filter..

Very interesting. What would cause the engine to cycle between 2000 and 1500 rpm without touching the throttle?

I appreciate all the knowledge sir, you're are truly helpful and I thank you for sharing your acquired know how🙌

I have had a couple of primer pumps go bad ,after replacing them the problem was solved

C13 acert here. It runs rough at cold idle(not so bad when warmed up, almost like a miss but I did a cut out test and everything came back fine. It runs the worst all the time if you have the park brake on and leave it in gear(automatic). Sounds like it skips a beat every few seconds. While driving it's totally fine. I bypassed the fuel tank and ran it out of a clean bucket of diesel and no change. I did a full valve adjustment Replaced fuel transfer pump replaced the 75psi regulator on the fuel manifold. Fuel gauge on the compucheck fitting reading about 70psi at idle. Any thoughts man? No logged codes. We just put this remane in in December of 2022 Edit: just checked another engine and the fuel pressure was at 65 via the compucheck fitting

Great info thank you for your knowledge!!

Great video, thank you. I do have a question on my C15. I have noticed the last couple of times I have changed the primary filthe fuel level is about an inch down in the filter. It used to be plum full. And now my truck does have a slight stutter. When you've got a higher demand for fuel. In a heavy pull, what could be causing that? I have tested pressure I'm around 95 psi at 1500 rpm. Thank you for any advice

You should have more likes buddy. GOOD JOB !

Very informative videos. Thank you

Excellent video sir.

I have a 2005 C7 serial # KAL72432 in a motor home. Once it starts it runs perfectly as long as you hold throttle above 1000 rpm. When you let off it dies will not idle. The mechanic changed the fuel pressure sensor on top of the block it ran fine for bout 15-20 miles then it started doing same as before . My oil pressure stays right at 40-60 psi.

Maybe you can help me. I have a 2000 Ford F650 with a 3126 Cat and dual 50 gallon tanks, one on each side. When the truck is parked on a slope, whichever fuel tank is on the low side gets all of the fuel transferred into it. I replaced the crossover and nothing changed. The vent on each tank is clear and the lines appear to be in very nice condition. This happens no matter how much fuel is in either tank. This truck has never spent a winter outdoors & only has 55,000 actual miles & always starts easily. It draws fuel from both tanks and also returns it to both tanks when running or being driven. I live in Minnesota ( cold outside ) but have had this issue since I purchased the truck in May ( warm outside ) of 2019 . If I only park the truck on a level surface I never have an issue. I hope this helps. Any and all advice is appreciated and thank you in advance. I have learned a lot from your videos so thank you again.

Just found your channel, you sound like an excellent mechanic. I'm wondering why, when I mash the foot feed to float a gear, I have no response..? 💛👍👍🚛

I have a 3406e that will not fire. I think it lost prime. Changing the prime pump today, it may have been letting air in.

Great video . I’m having a hard time finding that fuel tester adapter . Can you provide a link would love to buy one .

I have learned alot from your videos.

Great job showing and telling,see ya next time see ya bye.

Where can I get these fuel pressure testers please and thank you I’ve had a truck come in with fuel issues and couldn’t figure it out and would like more videos on fuel issues please thanks and thanks in advance for anyone’s help on finding fuel pressure testers for cat and other Diesel engines

It even informative than some of the institutions

I had a problem with secondary fuel filter swelling up because of over pressure on a 3116. Ended being a small piece of shrink wrap stuck in return line from someone not removing the plastic around filter properly.

Great videos and information thanks for sharing your knowledge.

I would love to know what kind of sight glasses yall use to check for air in fuel. Any part numbers would be appreciated

What might be causing a C15 to have higher filter restrictions. After new filters it would usually run between one and two on the Restriction gauge but now it's three or four. Fuel pressure drop maybe 5 lb still runs between 75 and 90 PSI. And it's kind of funny because the filter restriction gauge will get up to about 5 but after I fill the tanks it'll drop back down to three three and a half

I have a c12 that keeps losing prime. Replaced the relief valve and the hand primer. Do you have any recommendations for next steps on the dish?

Very good informational video!

Hi I have a 2006 t800 Kenworth C13 cat. Come off the road in the truck stop . Motor won't come up to speed. Had it towed diagnostics done tech said it was injector 4 and 6 . I replace them my self. Still doing the same thing starts hard idle is fine won't come up to speed. I run the flash test that was in your videos with the check engine light. I have a 6-4 code, 7-2,7-3 and 7-4 code.. oil pressure is 40 lb on Idel and 62 when accelerates.

We have Cat 3116 in a gmc 96 C6500 it has two tanks and it has a connecting line from passenger to the driver side tank but it's only drawing from the driver side tank and leaving the other full. I have dropped tanks cleaned them.

I have a 3126 cat 1998. Runs great starts great etc. New fuel filters just put on. Fighting a little problem. Itll sputter for a split second under a hard load then itll run fine again. Any advise??

Great video! Appreciate it man.

I have twin marine 3126 420hp engines. Recently I noticed higher fuel consumption (12.5% more) on the STBD engine coincidental with loss of WOT power/RPM's at 2500 in stead of 2800. No oil consumption. I run 40wt oil.

Very helpful info. Quick question I have a noise coming from the secondary fuel housing . Kinda like a sound of a bearing going out . Gould that be the pressure regular value?

Awesome job again thanks mate !

my engine when cold idles really rough ,and smoke out the stacks, replaced all 6 injectors , smoke disappears when hot ,idles rough still, but every once in while the engines smooths out and runs so good it is scary ,lots of power ,really works well, then for no reason runs rough again , could it be one of the reman injectors are bad ,injector driver module,fuel injection control module ,,,,I'm lost ,can't figure it out ,I will put it back on computer again to do cut out test,,,any suggestions ,,

Hi thanks for all the great videos! I am having an issue with fuel pressure in my cat c7. When the engine is running it seems to have good fuel pressure (I don't have gauges to test actual psi) but right after engine shutdown I lose all pressure. And the engine can't start. What would be the common cause of this?

In your opinion would an in tank fuel pump be better like thats in gas systems? It would eliminate the vaccuum portion of the diagram.

I am currently taking a break from Beaumans because business is slow. But I have been a little busy doing side work for people.

Am beginner .. Asking Fuel transfer pump on common rail system output s over 20000psi ..I didn't understand 125psi you talked about. thanks

I've had 3 fuel primer pumps go out on 3 different trucks truck was sucking to much air at the primer pump to start im assuming seals inside the pump go out truck cranks and cranks won't build fuel pressure pulled the primer pump off made a block of plate to go where the primer pump was truck starts right up

Hello, what causes a diesel engine not to start unless you start it with ether. It will run fine and start. But if it sets over night you have to hit it with ether. It is a cat engine in a dump truck not sure of the size I thought I heard my son say it was a 331? Maybe be in the 1990s ? He's had several people tell him what the problem might be and he's replaced different parts that were suggested could be the problem. But no change. Still hooked on ether. Any advice. Thanks

adept ape, I need help bad! i got a 2000 3406e on a freightliner. Truck was missing pretty bad around 1500 rpms, we ran an injector test and found out injector 4 was missing. we put a six pack,new cam,rollers,lifter bushings and new turbo. Truck runs great idling and you can stand on peddle when it’s parked and it sounds great. the moment you start driving it and it starts boosting truck runs like crap. almost like it’s chocking on boost. fuel gauge shows 90 psi on fuel pressure. told mechanic that was kinda low he said they forced more pressure in system and does same thing. i’ve been down for 3 weeks and don’t know where to turn. Thanks

Hi, your videos are great, perhaps you could help me with a problem I`m having the problem is we have a 2008 Ford F650 rollback back wrecker with the Cat. C7 I first noticed the fuel primer pump was extended whenever I checked the oil so I replaced it with another one from Caterpillar. Yesterday the pump knob and stem blew off along the road and left me sitting I towed it back and replaced it again. The question I have is this a symptom of another problem or just a coincidence or do I have something going on? If you could help me, it would be greatly appreciated. Thank you in advance. Don

Well done sir!

Great video

Got one where the hand primer keeps breaking popping out as if it’s building too much pressure what could be the cause?

Great video! You explained it very nicely. My degree from SLU (Stand'n Lean University) is kicking in right on time! I've got you locked in on my subscriptions list fur sure. I've have a 3406e in my 1996 W900L but i didn't hear you mention that motor. Is it the same block as a C15 but the gears are different in the front of the engine?

i have problrm with 3126 no power... fuel presure is good 80 psi ,boost up to 23 psi ,no smoke,start well,no check engine what can i check , TANK

Hello sir i need your help i have a cat 312d if i switch the hydraulic activation control liver the engine is straggling almost knocking

Love it! But you pretty much covered every size except the one I need, the c-10 😂 is it the same as a c-9?

Hi, I have a cat c15. It takes long crank in the morning. I'm assuming it needs check valve. Can you tell me where is the inlet check valve. Thanks

Great job thanks

Question. I have c15 with primary and secondary fuel system but would like to make it with a glass bowl system with one fuel filter. I've seen one on KZfaq and the thing I can't figure out where or how to buy is on the secondary they use a dummy filter 🤔. Obviously the primarily is changed to the glass bowl type filter and on the primary is left alone nothing is removed.

Very good video... thank U

C15 6nz. I have the problem of straight engine oil coming out of my fuel return line. Thinking it could be cracked head. It came in, had head gasket blown and #5&6 liner cracked. Replaced 5&6 pistons and liners new head gasket kit and spacer plate. Went to start fuel going in to front of head and only oil coming out of fuel return line.

Hello! Enjoy watching your videos! I have a problem with my cat c15, is acting like when you have a bad diesel filter which I already change and still doing the same thing, I change the turbo sensor and the diesel pump, diesel pressure valve and no luck. I had two mechanics look at it and they say everything looks good and no check engine light. Can you help me out with a clue please

I have a C7in my Sterling dump truck. It currently has a little inline primary fuel filter. Is it possible to add a bigger canister filter like the one you exampled in this video?

GOOD I REALLY LIKED IT

Hi morning. Does a bad fuel pressure regulator cause lost of engine power? I have a cat 3126 with very low power..

Impactful. Thank u

So you can change a low preasure fuel pump on a 3126 cat. with out pulling the huei ? Or do you pull the spring and plunger out and rebuild? THis huei has the oil resavoir.

So I have a c15 acert converted to single turbo. Last week in the morning it fired up and almost immediately shut down. I tried priming it but the plunger was hard as a rock. After a long crank like 20 or 30 second it started to light smoking and stinking of raw unburnt diesel. Then it cleared up and ran weak so I changed both filters. Every morning it's hard starting like I described above but runs flawless after it starts. Where would you start

First of all let me thank you I have a c15 nxs 12552... I am having a fuel knock for eight seconds when I start my truck after parking it for 10 hours in the morning only no other issues at all yesterday there was a lot of smoke white thick smoke while it was knocking if you can help thank you

Thanks for your videos. I am knew to this with a diesel pusher RV. How do you troubleshoot this when it is intermittent? Bought RV two months ago. Changed filters at shop that day. Last week on trip lost engine power. It came back on it's own. Same thing 1 hour later, low power RPM shooting around a bit. Then came back after a few miles with check engine on and off during the drive.. Before coming home, went to shop, change filters again and drain fuel from bottom of tank. 2 hours later, same issue within 2 miles, full power comes back. Drove 5 hours, all fine. Unloaded RV and drive to storage it started it again, Check engine light, low power, RPM hops. (Thought transmission maybe, but fluid is full and smells fine) I believe it is fuel. Have an appointing IN A MONTH at freightliner to look. I prefer not to wait that long.

I am having starting problems with a 3208 CAT, starting with easy start but not on it's own, trying to find glow plugs or heating element but can't see them anywhere, DOES IT HAVE THEM ?

HI I HAVE 2007 C15 PROBLEM I HAVE ONLY WHEN ENGINE IS HOT PUL THER LOAD THEN IDELING ROUGH COUSE OF FUEL PRESSURE WHAT CAN BE PROBLEM ?

Thanks for this video, am having a challenge on a marine CAT C4.4 engine, the fuel rail sensor switch, if it's disconnected the engine starts, but if connected back it won't start-up, a replacement was made and it did start, but later won't restart again, please kindly help, if there is something else am not doing right. Thanks a lot.

Driving a C15 that has had filters changed recently but has high restriction on guage in dash and seems low on power. What do you suggest? Partial plug before transfer pump?

I have a problem on my HEP12725 3126 cat. Heui pump went out so we replaced it as well as a transfer pump (ford part). Everything seemed to work great for a week or so. Than a small fuel leak was discovered (plastic hose that connects heui pump and water separator) that we are replacing right now. Than I could not start the truck in the morning. Unscrewed fuel filter and it was empty. Filled it up and started the engine using starting fluid. Truck ran for 10-20 miles and stopped again. Same process to start. I am hoping that replacing leaking hose and fuel separator will eliminate the problem but if not, what are my next steps? How do I troubleshoot my fuel system? Thanks a lot

I really want to know the caterpillar 962G engine not sound properly how Will know the fault of the diagnose injector pump system

good day adept ape. you got some really good videos, learning a lot. my name is noel. I'm a licensed on highway heavy duty, hear in Calgary. I have a question for you. I am working on my brothers 2003 GMC Top kick T6500 with a CAT 3126 in her. now my question is, for say 10 min driving down the road, it running great, than it looses throttle response, starts to run rough and white smoke, pull off the road and shut it off for 10 min. start unit back up and runs good for a few min, than back to shit, with not check engine light on. now first off I did a valve adjustment, no change, checked for the oil leak at the injectors all look good, test the power to injectors all good, than I checked the exhaust temp at the manifold and this is what I got, #1 183 F, #2 203 F, #3 217 F, #4 230 F, #5 223 F, #6 206 F. now from what I get out of that is I have a problem with the mechanical side of #1 injector, and possible #2 and 6, I assume that the temps should be close to the same. would you say that the #1 injector fail? now I just started out on my own and do not have a diagnostic computer, and hoping I can figure it out with out taking it to dealer to get it checked out. I do know that if I change an injector than I will have to take it to the dealer and have them calibrate the injector. if you have any leads for me that would be much appreciate. keep up with the good vidsthanksnoel

is pressure supposed to leakdown istantly like it did after you stopped trying to start the one with bad ecm? My c12 does that but i dont have any starting problems and i have good pressure. I have new filter base and pressure regulator with no leaks. Just curious becuase i read that the engine is supposed to maintain the psi after shutoff

@Adept Ape Hi, I’m having issues with my cat 320d 6.4 acert engine. The code is low fuel pressure on rail. The machine is still working perfect if you keep the engine speed dial on 8 or under. If you select 9 or 10 the engine enter on safe mode and loose power after a couple of minutes. Now It is doing on 8 too and I’m working the machine on 7 but it’s very slow. I have replaced: Fuel return valve (fuel rail) Low pressure pump 2 Inyectors (they had little return) Flush all fuel lines and filter base. Any idea if what could be happen? A lot of people say may be the high pressure pump but it is the only thing I didn’t change. I think the pump is very expensive for keep “guessing” the issue. All this parts where diagnosed and replaced by a cat technician

I fixed my friend's truck by seeing this video.. He had a vacuum leak on the small line that goes to the vacuum gauge on the dash I'm not a mechanic but he took it to a few mechanics here and none of them solved the problem because they didn't check that gauge line.

Hi, question?, you have talked about the C7 or 3126 fuel regulator at the back of the head. Information says it has an orifice that regulates fuel pressure based on a certain amount of flow and that it has a 5 psi back pressure check valve. Is there a way to test this back pressure function? And its hold function? I have seen a number of comments about it being an occasional problem but no clear way to trouble shoot. Or do you just throw one in and hope for the best? I am in Canada and it is a 340$ item at the Cat dealer or perhaps you know another source? Thanks, Bob

Hello. I enjoy your videos! Thank you! A question if I may... I have a 04 C8500 with a C7. There are no trouble codes. I have an extended crank situation. I've burnt up or broke starters from excessive cranking. Once it does start my running pressure at the filter is 70 psi and the pressure immediately drops off to 0 when I shut the engine off. My cranking pressure comes up very slow. Attempts to start slowly at around 50psi. I've replaced the fuel regulator and the Injection pressure sensor. Thanks for your time!

Have a problem with a cat c-15 accert (accert disabled). New rebuilt engine. New cat injectors. New head. Always has a starve for fuel issue at 1600 rpm. Everyone says to install a FASS pump. I think that is BSZ Where can I get proper fuel line sight glasses for this diagnostic application? What else is needed? Where to buy? I wanna see the in and out of fuel and see if I see air bubbles! Damnit. Could it be a bad fuel filter housing? Check ball? Is there a screen somewhere? Has a new fuel pump as well. Thanks!!!

Great video! I have a 2000 3116 that wont start, it has a hand pump on top of the secondary filter..... so somewhere between it and the fuel pump will be a transfer pump?? And being a smaller cat 50 to 60 psi cranking is ok for fuel pressure

My 3116 boggs down and acts like it’s starving for fuel. Changed the filters and it ran strong again for a couple of days and now it’s slowly starting to do the same thing. If I pump the primer pump a few times it’ll run strong for about 20-30 minutes then it’s back to losing power. Where the throttle linkage on top the pump it’s seems to be slightly wet. Any ideas where to begin, could it be the fuel pressure regulator? Thanks