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Frochevy 05-21-2018 08:53 AM

My Short bus build...
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I'm new to the skoolie builds and just purchased a 2007 Collins short bus built on a Chevy express 3500 chassis. I'm starting to do a few things to it so I thought I would start a new thread on it. Hopefully this will help someone if they have the same problems I am experiencing! If anyone disagrees with my thinking, I could be wrong. So please let me know.

It has an LMM Duramax diesel and 4L85E transmission. I had a trouble code of transmission component slipping on the way home and reduced engine power light came on. (Turned a 2 hour trip into 3-4hrs) I changed the transmission filter and fluid yesterday. I have not got to test drive it yet. The pan looked fairly clean and normal. No burnt smell in the fluid. I've been told different size tires on front and back can cause a situation with the abs and cause this code. I don't know for sure. I thought I would go ahead and change filter and fluid to be safe.

Another note- if you have a van and have the engine cover (inside the van) off, ensure there are no wires to catch when you reinstall the cover. I had a large red wire from the glow plug module crossed up on mine and cause it to arc at some point in the past. I fixed the wire and routed and zip tied any loose wires on top of the engine. (Keep away from heat sources! Turbo, exhaust,etc) I tied up the wire mess on the inside that goes to the control box for all of the lights, mirrors, ac etc which is part of the school bus options. I also used spray adhesive to re-glue the insulation and rubber seal to the engine cover. If those pieces are falling off of the cover it is almost impossible to install the cover correctly!

I'm currently working through floor plans and trying to decide which route to go. This forum has been amazing so far! Everyone has been great and given good advice on here!

More to come... seat removal will be next (once I can get some help from my wife)...

Fredinbelize 05-22-2018 07:59 AM

Good luck with your project.
I am just starting mine too.

Frochevy 05-23-2018 09:56 PM

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Originally Posted by Fredinbelize (Post 270799)
Good luck with your project.
I am just starting mine too.

Thanks! Good luck with yours as well!

I was able to work on the bus a little today. Started to pull seats out. They turned out to be more of a pain then I figured. Some are impossible to get an impact on either side of them. So I ended up cutting a few heads off the bolts. I only got 3 seats removed this evening. 7 more to go!

Anyone need any seats? What do you all do with the seats? Sell them on Craigslist?

magnakansas 05-24-2018 05:31 AM

I am Topeka. You have your bus. I am waiting for mine to be delivered from Colorado. Have fun with the work. Kinda cool to see that rail on the side with the bolts holding the side of the seat up and to the wall. Might be useful for attaching structure to the wall of the bus.

I think these buses are wired with the spaghetti system.

cheers, william

Fredinbelize 05-24-2018 09:15 AM

I took my seats out yesterday. I just broke them out. See my thread for pics.
I took the padding off and posted on Craigslist as scrap metal. They were gone in 30 minutes.

Frochevy 05-24-2018 09:49 AM


Originally Posted by magnakansas (Post 271240)
I am Topeka. You have your bus. I am waiting for mine to be delivered from Colorado. Have fun with the work. Kinda cool to see that rail on the side with the bolts holding the side of the seat up and to the wall. Might be useful for attaching structure to the wall of the bus.

I think these buses are wired with the spaghetti system.

cheers, william

We're not far from each other then! I looked at a few buses online in Denver area before I bought this one. What did you get? I do plan on using those tracks/rails for the build. Mine are riveted on so they won't be moved. Lol

magnakansas 05-24-2018 08:31 PM

me and mine
I have yet to see my bus. 1954 ford short bus, wayne body. There is a thread in they introduction section that shows more details.

Frochevy 06-01-2018 07:10 AM

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I had some more time to work on the bus lastnight. My wife helped me get 3 more seats out. And I also cha he'd the fuel filter/water separator. I've learned the Duramax vans have a different fuel filter setup than the trucks. Two filters almost directly under the driver seat. It was very easy to change. After changing, I cycled the key switch on about 4-5 times before starting. No problems there. I took for test drive and I still got the "Reduced Engine Power" light and it went into "limp" mode. Ugh! I'm still not sure what the issue is! Plan to take somewhere today and have a scanner put on it.

Another note: I went to tag office yesterday and got a 60 day tag for it to be able to test drive it before the RV conversion was complete. It was $8 and I just had to show proof of insurance, signed title in my name and sheriff inspection (since it was out of state).

I also went and talked to the appraisers office about the 3 key things to qualify as an RV.
1. Electrical system above 12v
2. Provisions for plumbing (she described this as "water hookups")
3. Heating - I asked her if the original heater in the bus would qualify, she said it just says heater so it would.

Frochevy 06-05-2018 09:19 AM

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I dug into the bus a little more last night. Was wondering if my trouble codes had anything to do with bad grounds or dirty connections. I found some corrosion on the fuse block. I've been told this 125a fuse is for the glow plugs. This might be setting off the glow plug module code. I decided to remove the batteries from the tray to clean everything up.

Frochevy 06-13-2018 12:53 PM

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After cleaning all of the battery cables up and junction blocks, I put everything back together and reset the code. I took it for a test drive and it still went into reduced engine power mode. The only code I have now is the low fuel rail pressure.

Later on the glow plug module light came back on. So that module may be faulty.

The good news is my transmission control module light hasn't came back on now, so I'm assuming it was a dirty electrical connection. The junction block (where multiple cables meet at the original battery mount location in the van) was very corroded.

On a different note, I purchased an Ancel AD410 scanner (OBDII code reader) for a little over $40 from Amazon. So far it is working great to check codes and reset the check engine light. I'd recommend if anyone is needing to reset their check engine light on anything 1996 an newer.

Mr4btTahoe 06-15-2018 01:35 PM

Can you test fuel pressure?

I'd say fpr issue or lift pump. If its lift pump related, would be a good time to upgrade to a FASS or Airdog system.

Frochevy 07-06-2018 11:21 AM

Fuel hose replacement
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I had some time this morning while it was cool to work on the fuel lines. I've done some research and I'm hoping my P0087 low fuel rail pressure is due to the collapsing/kinking rubber fuel hose sections on the 1/2" supply line. I decided to go with the Trident marine fuel hose from Larry B's for replacement. The line from the sending unit (at the tank) to the back of the fuel filter/water separator has two rubber sections. My steel portion of the line is very rusty. So I decided to replace the whole thing with hose. ( many people do this with the 2nd gen 12valve cummins engines) (I used this same hose on my Cummins with good results).

I removed the line, then used a dremel to carefully cut the outer clamp. Then you can pry the clamp apart and pull it away and slide the hose off. Be careful not to cut through the metal portion. Of the end/barb (it will be reused.)

Frochevy 07-06-2018 11:26 AM

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Forgot to mention this is an LMM Duramax (07)

I used approximately 56" of hose from the tank to the fuel filter/water separator. I used a good hose clamp to attach the new hose on each end.

Make sure your new hose won't rub anywhere. I had to tweak the fuel line from the sending unit down a little so the hose wouldn't rub on the edge of the frame. You could also pad the frame or the hose to prevent rubbing through.

I still plan to replace the other two sections of rubber hose. One by the trans and one by the fuel rail on the left side of the engine. More to come. I hope this cures my fuel rail pressure problems.

Frochevy 07-06-2018 11:27 AM

Sorry for the upside down pictures...

Frochevy 07-06-2018 11:50 AM


Originally Posted by Mr4btTahoe (Post 275535)
Can you test fuel pressure?

I'd say fpr issue or lift pump. If its lift pump related, would be a good time to upgrade to a FASS or Airdog system.

I just noticed your reply... I haven't tested fuel pressure yet. I was told this fuel line replacement is the most common issue on the Duramax. It only does it when it's hot out and when I get on the gas pretty hard. So makes me think the hoses are collapsing under acceleration.

Frochevy 07-06-2018 04:00 PM

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I changed out the other section of hose on the fuel line. It goes from the other side of fuel filter up to the fuel rail.

I got everything changed and took it for test drive with eventually the same results: low pressure fuel rail bank 1.


I watched data stream on my scanner and fuel pressure is 4500psi or so at idle and would peak aroubd 25-27k psi. One thing I did notice is throttle position stayed at 14.1%. So I'm not sure if that is part of my issue?

Frochevy 07-09-2018 10:16 PM

Duramax bottle test
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I did the "bottle test" yesterday. The LMM Duramax has a fuel pressure relieve valve on the driver side of the fuel rail at the rear. Many people say this will cause the P0087 low fuel rail pressure code to come on. The spring gets weak and let's fuel bypass and temporarily causes low fuel pressure. (This is my understanding). So you do a bottle test to redirect that fuel into a bottle to test if the FPRV is holding tight or letting fuel by. (It seems my FPRV is OK)

I let the engine heat up to operating temp and went and drove on the highway. Turned around and mashed on the pedal to take off and around 55-60mph it went into limp mode. Checked bottle and no fuel. Checked and same code I've been having. Ugh... what's my next step? Lol

NOTE: pictures are from van so looking at rear of engine inside van with engine cover removed. I had to remove glow plug module and heat shield to access the hose.

I also wondered if the fuel pressure sensor is reading right. I read that key on e fine off the sensor should read 1-1.8mpa which is 145-261psi. (Mine flashes between 71-107psi) so this could be another potential issue... more to come on this later.

Sorry to bore you all! I hope by documenting my troubles will help someone else in the future. The duramax Chevy Express vans are different animals than the trucks and harder to find info on...

magnakansas 07-10-2018 01:18 AM

do you have an in tank pump? if you do, install tee fitting in the line just after the fuel tank, make the line go all the way to the windshield.. install fuel pressure gage in the line and tape the gage to the outside of the window.. record pressure at idle, record pressure at failure .

go from there...

if you do not have an in tank pump, go the output side of the booster pump if you can, install tee fitting..........


that scanner only gives some insight at to what could be wrong, you have to use the 15pound computer ontop of your shoulders to find what is wrong. and it could be more than one thing.


joeblack5 07-10-2018 06:53 AM

Nice job on the fuel lines. If your fuel lines collapse then the inside pressure must be lower then the outside so the engine sucks harder then the tank can deliver. I do not know anything about Duramax and if they have a lift pump in the tank or on the engine but I would check tank screen filter and if a pump is in the tank then also the pump.

Good luck, J

Frochevy 07-10-2018 07:19 AM

From my understanding this is a common duramax problem. The trucks have only the high pressure pump at the engine (called cp3). The vans have the same system with the addition to a lift pump in the tank that only runs for first 30 seconds or so. So essentially the pump at the engine always "sucks" the fuel to the engine. The collapsing fuel lines have actually been a technical service bulletin that GM put out. That is why I started there replacing those areas.

I do appreciate the ideas. I think I might think about pulling the tank and sending unit next to see if the screen or pick up is plugged.

Yesterday I drove the bus in town to get a weight on it at the coop. (Scale wasn't available). I didn't have any problems with the code or limp mode yesterday and it was high 90's. I drove it normally without mashing the pedal or accelerating hard.

I drove the bus to work this morning to try stopping by the coop to get a weight today. I need an empty weight for the rv conversion tag...

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