'99 RE 8.3L Cummins last started around Oct '18

[Brewerbob]

As the title says, last time it was started was around Oct 2018. Batteries went dead and wasn't in any hurry to replace them. Have to move the bus for the lot to get paved. After bypassing the e-door lock, it turns over but won't start.

Fuel pump clicks like it always has (both front and rear). Glow plug light on dash cycles like it used to. Fuel filter is full of fuel.

Cycled the key several times without bumping the starter to see if that would "prime" anything. Tried pumping the gas pedal. Tried starting with pedal floored. Made no difference.

I know ether is not a good idea for diesels but is there a diesel version that I can get?

Any other suggestions?

[Mr4btTahoe]

You can use starting fluid... just disable the glow plugs or cycle the key on and wait a full minute for them to kick off.


Sounds like the fuel system has lost prime. If there isn't a way to purge the air out of the system, it'll take quite a bit of cranking to get it going. Might be wise to pull the fuel filter and fill it up with diesel fuel by hand. Spin it back on and continue cranking in 30 second intervals. Let the starter cool down a bit between attempts.


If it has an electric lift pump which it sounds like it does... cycle the key on. Wait 30 seconds. Cycle the key off. Repeat 6-8 times before attempting to start and see what happens.

[Brewerbob]

Originally Posted by Mr4btTahoe

Might be wise to pull the fuel filter and fill it up with diesel fuel by hand. Spin it back on and continue cranking in 30 second intervals. Let the starter cool down a bit between attempts.

Fuel filter is full.

Haven't been turning it over for 30 seconds at a time. That's a long time with that much current.

If it has an electric lift pump which it sounds like it does... cycle the key on. Wait 30 seconds. Cycle the key off. Repeat 6-8 times before attempting to start and see what happens.

The relays click twice (on and off), twice (about 5 seconds after turning the key, buzzer goes off,.. then again about 5 seconds later they cycle again), each (one at the fuel tank, presumably the fuel pump,... and somewhere at the rear of the bus). I was there by myself so I didn't have anyone to cycle the key while I was at the rear.

At about 30 seconds the buzzer comes back on.

I cycled the key, turning it off after the rear clicked on/off the second time. Then turning it back on. Repeated this 10 times in a row and then tried starting again. No change in even the sound of it turning over.

I do agree it sounds like it's not getting fuel to the cylinders but I don't know how to check that. It's a little bigger than a lawn mower and doesn't have spark plugs I can yank out. I don't even know where the injectors are on this puppy. Even the (rubber) fuel line from the fuel pump goes to some weird looking rectangle box where it comes out with another (steel) line.

[TJones]

If you have an ISC it has an electric lift pump that only runs for 30 sec to prime the injector pump. The injector pump has a mechanical pump that pulls the fuel from the fuel tank when the engine is running.

You should be able to hear the electric pump run when you turn the key on but are not cranking the engine. You DO NOT want run the injector pump with out it being primed or it will die and is expensive to replace.

First I would listen for the electric lift pump at key on. If you hear it run I would then remove the line between the lift pump and the injector pump to check that the lift pump is pushing fuel. If the lift pump runs but does not push fuel you could have a clogged filter or cracked fuel line or bad lift pump. If your getting fuel to the injector pump and it doesn't start you have bigger problems.

Edit: The lift pump lives in the engine compartment not in the fuel tank.

https://youtu.be/xp-YuZ5uQYY

Ted

[Brewerbob]

Crap, I had a reply but it didn't like my login. Let's try this again...

Originally Posted by TJones

If you have an ISC it has an electric lift pump that only runs for 30 sec to prime the injector pump. The injector pump has a mechanical pump that pulls the fuel from the fuel tank when the engine is running.

Yep, ISC.

You should be able to hear the electric pump run when you turn the key on but are not cranking the engine. You DO NOT want run the injector pump with out it being primed or it will die and is expensive to replace.

I've not heard anything extra nor missing. That's not to say the pump is too far back or too quiet for my old ears.

First I would listen for the electric lift pump at key on. If you hear it run I would then remove the line between the lift pump and the injector pump to check that the lift pump is pushing fuel. If the lift pump runs but does not push fuel you could have a clogged filter or cracked fuel line or bad lift pump. If your getting fuel to the injector pump and it doesn't start you have bigger problems.

Filter was VERY full but I didn't take a look at the quality of the fuel.

Edit: The lift pump lives in the engine compartment not in the fuel tank.

https://youtu.be/xp-YuZ5uQYY

Ted

Ah, that answers a couple of questions. I would have expected something on top of the tank. That's definitely the rectangle box I was talking about. Beast of a pump with a rubber line coming in and steel coming out. No reason for all of that unless you're making some real fuel pressure. If that's the case, why (and where) do you need an injector pump?

I'll go watch the rest of the video now. Maybe it's already answered

[Brewerbob]

Originally Posted by TJones

https://youtu.be/xp-YuZ5uQYY

Ted

Holy ****!! I expected some high pressure but 17,000 psi?!? Sweet baby Jesus!!!! I figured 200 maybe 300 psi.

It mentioned an air bleed but doesn't look like it's anything I can open to make sure the air is out. And since it's part of the CAPS, it's likely to be 5,000 + psi.

It also shows tank -> lift pump -> filter -> then CAPS. So, if I pour some fuel out of the filter and it refills then the lift pump is doing its job. I'll pour it out into something clean in case I need to fill it back up manually.

P.S. Thx for the video. That was great and hopefully I don't need to go anywhere near the CAPS system.

[WIbluebird]

I should mention that these Cummins engines don't have glow plugs, only grid heaters.

Sounds like it lost prime somehow.

[Brewerbob]

Originally Posted by WIbluebird

I should mention that these Cummins engines don't have glow plugs, only grid heaters.

Sounds like it lost prime somehow.

You positive about that? I'm almost certain I read somewhere that mine has plugs not grid.

[Brewerbob]

Definitely lost prime. Dumped about a quarter of the fuel from the filter. Did the key thing several times. The filter did not refill. I can't turn the key and get to the back of the bus in 30 seconds to test the voltage at the lift pump.

I'm thinking about disconnecting the inlet hose and pouring diesel down that to get the supply line at least partially full. That's assuming it doesn't just all drain back into the tank

[cadillackid]

Originally Posted by Brewerbob

Definitely lost prime. Dumped about a quarter of the fuel from the filter. Did the key thing several times. The filter did not refill. I can't turn the key and get to the back of the bus in 30 seconds to test the voltage at the lift pump.

I'm thinking about disconnecting the inlet hose and pouring diesel down that to get the supply line at least partially full. That's assuming it doesn't just all drain back into the tank

hook a test light to the lift pump wires and tape the light to the side of the bus.. when you turn the key you can see the light in your mirror(unless your bus has a rear control center for ignition / engine like the navistars do).

[Brewerbob]

Originally Posted by cadillackid

hook a test light to the lift pump wires and tape the light to the side of the bus.. when you turn the key you can see the light in your mirror(unless your bus has a rear control center for ignition / engine like the navistars do).

It has the remote start but the button is frozen in place. I haven't tried smacking it with a hammer but it'll need some work too.

Good idea on the light bulb tho. Gf is coming up soon so I'll just wait.

[Brewerbob]

Random pic of the 4935007 lift pump. One of the 4 part # for my engine. Haven't ordered one yet because.... see below.



Two wires going into the lift pump. I'm assuming this is supposed to be the 12v to turn it on. When I measured the voltage I expected 0v or 12 v. Line good or line dead. What I got was 1.78v.

Key off 0v
Key on 1.78v
Key on > 30 seconds 1.78v
Key start 1.5 something v.

I don't know what to do with this. I've got a wiring diagram for the bus. Haven't looked yet but not sure this would be included since the engine and ECU isn't.

[TJones]

Originally Posted by Brewerbob

Random pic of the 4935007 lift pump. One of the 4 part # for my engine. Haven't ordered one yet because.... see below.



Two wires going into the lift pump. I'm assuming this is supposed to be the 12v to turn it on. When I measured the voltage I expected 0v or 12 v. Line good or line dead. What I got was 1.78v.

Key off 0v
Key on 1.78v
Key on > 30 seconds 1.78v
Key start 1.5 something v.

I don't know what to do with this. I've got a wiring diagram for the bus. Haven't looked yet but not sure this would be included since the engine and ECU isn't.

There must be a relay with a timer that turns on at key on supplies power for 30 seconds then shuts off. My guess would be the relay lives in an electrical box in the engine compartment. If you can tell what color wires run to the pump you should be able to find them running to the relay in the electrical box if the relays aren't labeled.

Ted

[Brewerbob]

Originally Posted by TJones

There must be a relay with a timer that turns on at key on supplies power for 30 seconds then shuts off. My guess would be the relay lives in an electrical box in the engine compartment. If you can tell what color wires run to the pump you should be able to find them running to the relay in the electrical box if the relays aren't labeled.

Ted

Red and probably black. Wasn't paying too much attention to the other wire. Probably easier to just track the loom. Thinking about putting 12v across the pump directly. See if the pump itself works.

[Rwnielsen]

Originally Posted by Brewerbob

Red and probably black. Wasn't paying too much attention to the other wire. Probably easier to just track the loom. Thinking about putting 12v across the pump directly. See if the pump itself works.

Be careful with bus color codes, they tend to be a bit whimsical. I have a buzzer with a white w/black trace for switched hot and red for negative. Nothing is sacred.

[Brewerbob]

Originally Posted by Rwnielsen

Be careful with bus color codes, they tend to be a bit whimsical. I have a buzzer with a white w/black trace for switched hot and red for negative. Nothing is sacred.

Thx. Yeah, I know. That's why I'd trace the loom instead. Solid red is too common a color. Cars at least tend not to repeat too much.

[Brewerbob]

Running 12v straight from the battery to the lift pump did nothing at all. I seem to have lost the 1.78v too. Going to order a new pump but I'm not sure that's the only issue. Would be nice if it decides to start tho.

[cadillackid]

is that a straight motor pump or is it driven by a PWM signal?

[joeblack5]

It looks toe that it is an electromagnetic membrane . pump. If you connect it to the battery it should make a click. Then you release it and make the contact again..

So test some more before you spend a couple of hundred bucks..

It looks like a low pressure transfer / lift pump. So you could replace it for a low grade fuel pump to at least get fuel to your IP and get the bus started..

I think you ecm gives electric pulses to activate the membrane.

Good luck
Johan

[cadillackid]

so similar to a webasto clicker pump it sounds like.. if thats the case you should be able to clickety clack yourself some fuel pressure by toucing and untouching the wires..