No start. Thomas Saf-T-Liner / Cat 3216.

[JacobFerguson]

Hello Skoolie friends, thank to you all in advance who can help with this one. My bus is not starting.

TL;DR / best guess:
2003 Thomas Saf-T-Liner HDX with CAT 3126 is having trouble starting. It cranks, won't turn over. Sits quite a bit in the city. Short drive every 7 days. I think that may be the source of the problem... batteries and fuel. I replaced the batteries and fuel filter, filled outer holes of new fuel filter to top with diesel, primed, it wants to start after priming, I hear bubbly air sound during priming though (normal?), priming pump doesn't get more resistant, actually was hardest at first and now has gotten easy, so I'm wondering if I may have caused compression problem / leak in fuel lines (unless its normal to hear air/bubbly sound when priming and for it to not get more resistant on my make/model of bus).

https://www.youtube.com/watch?v=ou2_SibNuws

Long story w/ video
I bought a *healthy* 2003 Thomas Saf-T-Liner HDX w/ 7.2 liter CAT 3126 engine and Allison MD3060 auto transmission over a year ago, full size 40'. Never had a problem with it until now. It sits a lot like it did last winter, didn't have problems then. Weather just started turning cold again, one day couple weeks ago I started it and it ran weak with a rattle for 10-20 seconds and conked out. I immediately started it again and it ran fine that day. Drove it.

Days later it stopped starting. Battery voltage on dash would be 11.3 volts or so as usual, and get only as high as 11.9 - 12 volts after waiting 30 seconds. When cranking it would drop significantly and interior dome lights would flicker. Roadside assistance came, tried to jumpstart batteries with three different battery packs. No luck, I "killed" em all he said. Cold cranking amps on my batteries were reading as low as 200-300 range when he measured them. Took old batteries to store, had them charged to make sure before buying new ones. They reached only 7xx cold cranking amps after charge (rated for 950). I then replaced all three batteries. New batteries are group 31's, 950 cca, same exact specs. Connections are clean and tight. Was showing 12.8 - or was it 13.8 - volts on dash before all my cranking over the last couple days. It's at 12.5 now, starting to get cold again after couple days nice weather.

Also changed fuel filter thinking it may be an "algae" thing / dirty fuel from initially sitting a couple years with only 1/4 tank before/during purchase. After replacing fuel filter yesterday, I tried to turn key and no crank (I didn't know engine lid needed to be closed). I then tried priming with the pump even though I had already filled the new fuel filter to top with diesel. Pump was extremely resistant right off the bat. The pump did not get more resistant like people say it should, it actually got easier, much easier. I forced it with my bare hands. I may not have known my own strength and might have caused a leak now (I don't know), unless it was just hard at first from all the rust/grime and it is supposed to be easy forever now. I've now pumped it 1000 times over two days, easy to pump every time. Engine wants to start immediately after pumping, not so much after not pumping. During pumping I can hear some type of air/bubbling sound, hard to identify where, but in the general vicinity of the engine block and fuel lines. This may be normal, I don't know. But immediately after pumping is when the engine does its best trying to turn over. White and then dark grey smoke coming out exhaust, but then after sitting for 10 minutes or so, it's back to just a strong crank (batteries good). I don't want to destroy my brand new batteries or the starter though from too much cranking. The voltage has dropped and I may need to charge the batteries soon.

Maybe a month before all this, I put the most diesel in I've ever put in. I filled tank to 3/4 for first time, new diesel with stabilizer. That's why I'm thinking I may have unsettled some "algae" or filth in the tank. I have some biocide and anti-gel coming from Amazon. Not going to matter though if I can't start the bus and get it flowing though the system right. Don't want to do ether / starting fluid because posts online have cautioned against. I think my engine might not have glow plugs but an intake heater from what I read, even though the roadside assistance guy thought it had glow plugs and suggested ether, which we didn't end up doing thank God.

I drained fuel/water separator of all water. I unscrewed the drain and a little bit of grunge/filth was present on top. Again, could be normal. I didn't change this filter yet.

This is my first diesel vehicle. There was a time months ago after driving it that I smelled a foul rotten egg smell, I got worried about the bus when I smelled it. That's another thing that makes me think an "algae" issue in tank cause I read online that smell is a tell-tale sign. But I only smelled it once or twice. Why wouldn't I always smell it after running? And it was super strong all at once that day. I concluded it was most likely not my bus, but out in the environment in my dirty city somewhere.

Also, transmission light comes on and stays on with key turned in ignition. I can't remember if that's normal and it just goes away *after* starting or if it shouldn't be on even before starting. It hasn't been on in the past after starting and driving. I've never noticed any lights on my dash.

For over a year now, my routine has been the same. I park the bus in the city and rotate it from parking spot to parking spot every 3-7 days (only every 7 days lately). That means just a short city drive not even reaching top speeds of 55mph, a few miles at most, maybe 10-15 min drive. Sometimes I take it out on the highway and get it up to operating temps I do believe, maybe 2 times a month. I plan to drive it to full operating temps every 3 days now after I get it fixed. The whole diesel no-start thing is a new animal I'm not familiar with yet, but it appears to be a common thing for diesels, more so than gas engines anyway. My instincts tell me all this is from something minor.

Thanks for any help. I'm not opposed to leaving somebody a $ tip if they help me get it figured out.

Appreciate it.

[PorchDog]

Your engine is turning over plenty fast for it to start. It sure seems to me that you have air entering the fuel system prior to the priming pump, or you have a bad primer pump. It should pump up and get hard as the air is purged from the system.

I am not sure but I think if you had a transmission error-- the engine would not turn over-- or maybe it would start but not come out of neutral.

I think your batteries and voltages -- especially with the new batteries-- are all just fine.

A boat fuel tank full of diesel connected where fuel normally comes to the first fuel filter might be a way to at least rule out an air leak and allow you to move the bus.

[PorchDog]

The day it cranked and ran poorly for a while, and then finally cleared up and ran OK -- it might have ran poorly while it worked its way through the air bubbles in the fuel, and then ran OK. Now after sitting, maybe a lot of air has gotten into the system such that it will not start.

I think this bus has a HEUI fuel system, and that is whole nuther story-- but I would start with trying to make sure you don't have a bunch of air in your fuel supply.

Also-- when you are attempting to use the primer pump, you should probably crack open a line on the upstream side of the pump, (the output or pressure side of your primer pump) and when you start seeing fuel flow from that loosened connection-- you know you have successfully primed the injector pump.

[JacobFerguson]

Thank you for the first reply. I *wish* that I did have a boat.

Originally Posted by PorchDog

The day it cranked and ran poorly for a while, and then finally cleared up and ran OK -- it might have ran poorly while it worked its way through the air bubbles in the fuel, and then ran OK. Now after sitting, maybe a lot of air has gotten into the system such that it will not start.

That would make sense I guess, although I was kind of leaning towards it doing so because of the low batteries voltage/cca. If it was air in the fuel, then the batteries needing to be replaced would be mere coincidence. (Which is possible).

Originally Posted by PorchDog

Also-- when you are attempting to use the primer pump, you should probably crack open a line on the upstream side of the pump, (the output or pressure side of your primer pump) and when you start seeing fuel flow from that loosened connection-- you know you have successfully primed the injector pump.

Would you happen to know which of the two lines are on the upstream side in the pic below? (Video). I've unfortunately already pumped it 1000 times, but they may be worth a check.

[PorchDog]

The line should go the high pressure fuel pump which is mounted on the engine. The high pressure pump is gear driven off the front of the engine.

[ewo1]

I would start out by replacing the prime pump. My friends dt466e had a similar problem. Just wouldn’t start one day out of the blue!

We tried priming it but felt very weak resistance while pumping the primer. Swapped it out, primed it and started up again, no more problems!

On my personal truck, I got an LBZ Duramax. Every so often, maybe 2 or 3 times a year it manages to loose prime. It will start, I put it in drive then it stalls.

I get out push the primer 2-3 times and cranks right back up!


Also on the tranny, do you mean the dash light comes on?
I know first hand that if the push pad does not light up, it will not even crank over at all so I fought your starting problem might be the tranny.

Keep us posted, I would like to learn more about cat’s!

[Meathead]

Note that I answered your PM.

These are the filters that I have used with success.

Fuel filter CAT 1R-0751
Or Napa 3626
Fuel/Water Separator
Fleetguard FS19513
Oil filter. 1R-1807

2001 cat3126b. 210hp

I notice you have a different number on your filter. May be worth a double check.

[emoji3522]

[Meathead]

Never mind. My cross reference chart says that the Napa 3377 and 3626 are both acceptable for our busses.

Just tryin to help. [emoji1739]

[emoji3522]

[JacobFerguson]

Originally Posted by PorchDog

The line should go the high pressure fuel pump which is mounted on the engine. The high pressure pump is gear driven off the front of the engine.

Ok it looks the like the back line in pic goes to the front, I will check that out. I think I read once you can just crack them both open?

[JacobFerguson]

Originally Posted by ewo1

I would start out by replacing the prime pump. My friends dt466e had a similar problem. Just wouldn’t start one day out of the blue!

We tried priming it but felt very weak resistance while pumping the primer. Swapped it out, primed it and started up again, no more problems!

Do you think it might more likely be the fuel line coming off the pump though, and not the pump itself? Because in the video it really wants to start immediately after I pump it. So that seems to imply to me that the pump works, and maybe air is getting in after no pumping and sitting, even just for a few minutes.

Originally Posted by ewo1

Also on the tranny, do you mean the dash light comes on?
I know first hand that if the push pad does not light up, it will not even crank over at all so I fought your starting problem might be the tranny.

Keep us posted, I would like to learn more about cat’s!

The "check trans" light just comes on with the key in and turned. It stays on. I've never seen it stay on after starting the engine though, unless it does now (which of course I don't know for sure because I can't start the engine!)

[JacobFerguson]

Thanks a lot for all the PM info MeatHead, I'm feeling confident that's what the issue is now.

MeatHead has the same bus and says he doesn't hear any bubbling, and his pump gets more difficult after a while.

I've pumped mine 1000 times.

[Meathead]

Originally Posted by JacobFerguson

Thanks a lot for all the PM info MeatHead, I'm feeling confident that's what the issue is now.

MeatHead has the same bus and says he doesn't hear any bubbling, and his pump gets more difficult after a while.

I've pumped mine 1000 times.

Similar thread:

Bus won't start after replacing fuel filters. HELP!!!
https://r.tapatalk.com/shareLink/top...ink_source=app

[CoffeeGuy]

Can you get access to CAT ET? I had a random crank-no start issue with my 3126 and even though I did not get a check engine on the dash, when I hooked up ET I found an error that led me directly to the crank speed sensors. There are 2, one is used to establish timing during start. You could check them for resistance without pulling the sensors but because they’re located behind the compressor, they’re a bitch to get to. I managed to replace mine without removing the compressor but it took about 4 hours of cursing and 3 different long nose plier sets.

My point is that it’s not always fuel when it cranks but doesn’t start. Diagnostics before swapping out parts is always the wider path.

[BFlinn181]

Since this issue didn't show until you changed the fuel filter(s), pretty sure you've just lost prime and have air in the line between the filter and the high-pressure pump. The fact that your fast cranking engine isn't showing any smoke is an indication there's air in the lines instead of fuel. You also probably have a grid heater in the intake that comes on for a period of time to pre-heat the air to help start on cooler days. The grid heater shuts off after, showing the jump in voltage.

[JacobFerguson]

Thanks all for the holiday replies. I got a bit sidetracked and unmotivated to fix it for a week or so, but I think I'll go for replacing the fuel/water separator filter right now, and those fuel lines. I guess the goal is to get it to hold prime and then figure things out from there. This is my first no-start so I'm starting from scratch learning the mechanical side of the bus now, now that the conversion is done. I'm trying to figure out where to find parts and if those lines can be changed without leaking fuel all over the place for example. All I've done mechanically on the bus so far is replace batteries and a fuel filter. I was hoping to make it past the winter before learning it all :-/

Originally Posted by Meathead

Similar thread:

Bus won't start after replacing fuel filters. HELP!!!
https://r.tapatalk.com/shareLink/top...ink_source=app

Thanks Meathead, yea I saw that one. Glad it got revived. I usually search the skoolie threads though before I post and bother anyone for help. This site has unknowingly been a lifesaver to me on the conversion side so far and a lot of you have helped me build this thing whether you know it or not.

Originally Posted by CoffeeGuy

Can you get access to CAT ET? I had a random crank-no start issue with my 3126 and even though I did not get a check engine on the dash, when I hooked up ET I found an error that led me directly to the crank speed sensors. There are 2, one is used to establish timing during start. You could check them for resistance without pulling the sensors but because they’re located behind the compressor, they’re a bitch to get to. I managed to replace mine without removing the compressor but it took about 4 hours of cursing and 3 different long nose plier sets.

My point is that it’s not always fuel when it cranks but doesn’t start. Diagnostics before swapping out parts is always the wider path.

Where do you hook it up at? I looked into diagnostics / testing before and was going to get one of those obd2 scanners (like for a car) but realized there's no input under the dash anywhere.

Originally Posted by BFlinn181

Since this issue didn't show until you changed the fuel filter(s), pretty sure you've just lost prime and have air in the line between the filter and the high-pressure pump. The fact that your fast cranking engine isn't showing any smoke is an indication there's air in the lines instead of fuel. You also probably have a grid heater in the intake that comes on for a period of time to pre-heat the air to help start on cooler days. The grid heater shuts off after, showing the jump in voltage.

I hope so but it wouldn't start before I did the fuel filter, which is why I replaced the batteries first. But now it appears to be not holding prime. You are right about grid heater.

[Truthseeker4449]

Originally Posted by JacobFerguson

Where do you hook it up at? I looked into diagnostics / testing before and was going to get one of those obd2 scanners (like for a car) but realized there's no input under the dash anywhere.

Large vehicles do not use OBDII, instead they use J1939. Laptops with specialized software are used with special adapters to communicate. Normally this software is sold by rather expensive subscriptions, but there exists a market to sell hacked software without a subscription. This is normally installed by the seller remotely into your computer. As such, it is very highly advised this software is installed on a laptop that is used for nothing else but diagnostics and never comes into contact with sensitive information as it's always possible the installer may put spyware in.

Caterpillar ET is the factory software and I bought a dealer license version with a factory password generator from CarSoftDiag. Works great for me and I've used it at work on more than one occasion. Stupid C13 emissions garbage...
https://carsoftdiag.com/product_info...oducts_id=1219

Now on your bus you should have two options to connect. There is an electrical compartment on the passenger side of the dash, usually secured with triangular locks that take a special key that I obtained from my local Thomas dealer. Below is a picture of what mine looks like with the cover removed. In my case there was still an adapter splitter cable in place that was used for a telemetrics system. The green piece on the right side is what a J1939 Connector looks like, and the original connector is to it's left where the black round piece.



Now if I remember right, you can also take the bolts out of the front of the control panel in the engine bay and open it up to reveal another J1939 connector.

Definitely need to get the priming issue sorted first. It's possible the original fuel primer has gone bad, but it also can take a very long time to get the system primed with the hand primer. I recommend prefilling the water separator with fuel and giving the primer 100 pumps. Yes it sounds like a lot, but this is what I have to do at work for some engines after a filter change or fuel system repairs. If the primer doesn't get any harder to push in after 100 pumps, then the possibilities are likely a bad primer, a leak in the supply side to the hand pump (which will most likely not be visible as it will be sucking air into the system), or a fuel leak after the hand primer (which could be visible as this side will be pressured). This sort of fuel leak could also be an internal leak in the cylinder head or fuel pressure regulator.

Yes this is a HEUI engine, this engine does not have a high pressure fuel pump. The big pump on the front of the engine is for making a high pressure oil for the injectors. Check out this video to familiarize yourself with the 3126 engine.

https://www.youtube.com/watch?v=cj2wfZwMJP4

[CoffeeGuy]

Originally Posted by JacobFerguson

Where do you hook it up at? I looked into diagnostics / testing before and was going to get one of those obd2 scanners (like for a car) but realized there's no input under the dash anywhere.

There is a place to hook up, but it doesn't look like the OBD2 interface for an automobile. Your Cat has either a J1939 or J1708 connector. They both look similar, with a center point surrounded by several additional connection points arranged in a daisy pattern. There are NEXIS OBD clones that you can buy from eBay that come with Cat ET software that works on older engines, you need a WinXP computer to run the diagnostic software but you're talking hundreds of dollars versus thousands for the real deal setup.

Personally, I won't hit the road without Cat ET as part of my tool kit.

[JacobFerguson]

Thanks a lot guys for this info about diagnostics. If there's a similar hack for a service manual, that would be great to know.

Originally Posted by Truthseeker4449

Definitely need to get the priming issue sorted first. It's possible the original fuel primer has gone bad, but it also can take a very long time to get the system primed with the hand primer. I recommend prefilling the water separator with fuel and giving the primer 100 pumps. Yes it sounds like a lot, but this is what I have to do at work for some engines after a filter change or fuel system repairs.

Will do. I filled the fuel filter with diesel when I changed that, and pumped it 1,000 times... one thousand. It wants to start immediately after pumping.

Originally Posted by Truthseeker4449

If the primer doesn't get any harder to push in after 100 pumps, then the possibilities are likely a bad primer, a leak in the supply side to the hand pump (which will most likely not be visible as it will be sucking air into the system), or a fuel leak after the hand primer (which could be visible as this side will be pressured). This sort of fuel leak could also be an internal leak in the cylinder head or fuel pressure regulator.

When you say the possibilities are a leak in the supply side or a fuel leak after the hand primer, I'm assuming you're talking about the two fuel hoses coming off of the hand primer assembly? If so, that's what I've been thinking as well. That's why I'm calling around past couple days trying to find those two parts, but so far one dealer says the hoses need to be made from scratch and can't give a price quote. That's quite disturbing, haha. The hand primer is only $125 I think, but I'm not sure that's the issue because I'm hearing airy sounds near the hoses after pumping.

If anybody can tell me how they themselves would go about buying and replacing those hoses (or if that's even the first thing you would do based off of the diagnosis I've posted), that would be a huge help.

Here's another video of me trying to understand lol.

I'm getting ready to post it to the heavy duty mechanic(s) at JustAnswer.

[JacobFerguson]

Hey everybody sorry about the long posts ^ above. I'm reading my own thread back and it's like wayy too long, sorry about that I will have to work on my tl;dr's.

A little update: I installed a new primer pump and refilled the fuel filter and the bus fired right up. I only had to pump it less than 10 times before it got hard to push, but I also had to fill the fuel filter with diesel again because it was almost empty for some reason. *This* is the issue apparently. The bus ran for about 5-10 min and the conked out again. I took off the fuel filter and checked it again, and once again it was almost empty. Repeated again (x2). I feel like somebody can probably diagnose the problem now, with that info?

I'm about to start researching and ask the diesel mechanics at JustAnswer.com to see if anyone knows why it would do that. Right now my best guess is what I originally thought: maybe I let the bus sit around too much and the fuel has either developed an "algae" and/or gel issue and is being clogged up somewhere.

[dbsoundman]

Originally Posted by JacobFerguson

Hey everybody sorry about the long posts ^ above. I'm reading my own thread back and it's like wayy too long, sorry about that I will have to work on my tl;dr's.

A little update: I installed a new primer pump and refilled the fuel filter and the bus fired right up. I only had to pump it less than 10 times before it got hard to push, but I also had to fill the fuel filter with diesel again because it was almost empty for some reason. *This* is the issue apparently. The bus ran for about 5-10 min and the conked out again. I took off the fuel filter and checked it again, and once again it was almost empty. Repeated again (x2). I feel like somebody can probably diagnose the problem now, with that info?

I'm about to start researching and ask the diesel mechanics at JustAnswer.com to see if anyone knows why it would do that. Right now my best guess is what I originally thought: maybe I let the bus sit around too much and the fuel has either developed an "algae" and/or gel issue and is being clogged up somewhere.

Might try pulling the fuel line coming into the filter, then using an air compressor to push air back through the fuel line into the tank? (Vent your tank's cap first!) That would at least give you a way to try to clear any crud out of the fuel line...