Cummins 5.9 12v crank no start no fuel

[AZtom]

Ok so here is my dilemma.
Bus has been sitting for a couple of months while I work on it. I have started it periodically just to make sure everything was working. I attempt to start it now and it cranks over but doesn't start.

Through my troubleshooting I discovered there's no fuel going to the injectors I loosened up an injector line and cranked but ....no fuel I tried the manual pump pushed that thing about a hundred times.... no fuel. I loosened up the bleed valve on the fuel filter again .....no fuel. I had my wife try to turn over the engine while I went underneath next to the tank to see if the fuel pump was even kicking on. I could not hear anything no humming so it sound like there was no power to the pump.

I trace the wires back and found that the fuel pump wires was fused to the muffler I cut them and repaired the wires I took a voltmeter and as I had the ignition on there was 7 volts going to the wires where they were fused I went to the top of the tank in that little access hole and the voltmeter read 4 volts which to me seems very low to power a fuel pump. I don't see a way to remove the fuel pump either it looks like it's built into the tank.

Anyway I'm at a loss any brainstorming ideas would help, thanks.
Tom

[cycle61]

Seven (or four) volts isn't gonna get it. Have you checked the grounds on the pump? And where exactly are you measuring, across the incoming wires or ???

Sounds to me like the circuit is floating, with a high resistance or open circuit on the ground.

[AZtom]

So this is the top of my tank through the access panel. These wires are the only to wires going to the tank so I figured these are the wires to the pump but again I'm guessing. The configuration is odd to me I expected to see a larger pump head that can be removed.

I put voltmeter on those wires

[cycle61]

Ok. Check each wire's voltage to a clean spot on the bus frame where you can get a good ground. 4v across the pump means, in a 12v system, you have 8 volts going somewhere else. If the voltages measured to frame are 12 and 8, you have a bad ground. If they're 4 and zero, you have a bad circuit feeding the pump.

[Booyah45828]

Guys, that's not a pump. That's the fuel sender. It's what tells the gauge the fuel level.

[Booyah45828]

The lift pump on a 6bt is mechanical and is located on the side of the block.

[AZtom]

Ok well I'm learning stuff so this is good. So there is no electrical fuel pump in 96 Cummins 5.9 12v

So that pump with a manual plunger appears to be the lift pump. This is what I was manually pumping in effort to get fuel to the injectors.

[Booyah45828]

If there is one, it's aftermarket.

It's hard to tell from your picture but I would assume that that is the lift pump.

Open the bleed at the filter and pump that until you get fuel.

If you don't get fuel, either the tank is empty, fuel line between the tank and pump is leaking, or the pump is junk.

[cycle61]

Well then. So much for that troubleshooting sequence.

[AZtom]

Okay I ran to the gas station and filled up all the fuel cans I had and put 10 gallons in. I opened up the bleeder valve on top of the fuel filter..... I tried turning it over and manually pumping the transfer pump again no fuel. I follow the lines from the tank all the way to the engine and I did not see any leaks or wet spots so I think they're good.

So process of elimination I should try to replace the lift pump? And cross my fingers?

[BlackJohn]

Take the fuel filter off and see if it is full or empty. You need fuel there before the injectors get some. And you have to get rid of the air in the fuel lines for fuel to appear.
If you get fuel as far as the injection pump then star opening the fuel fittings on the injectors, one at a time, the back one first I would think and move to the front. Will take time but , luckily you have the wife there to crank as you bleed air.
How new/old is the fuel filter? And is there a water separator with it? Drain that before anything else.


Good luck,


John

[Ronnie]

I would not crank the engine to get fuel. Use the plunger on the fuel pump until you get fuel through to the injection pump. broom handle or stick might make it easyer. That is why it is there, and saves your battery.

In a pickup there is no fuel filter before the lift pump, however not sure on a bus, there might be one, it would be worth checking to see if there is one. If so change it and be sure to fill as best as possible before putting it on.

Not likely but.... the fuel tube in the fuel tank could have failed/rusted fallen off. Taking the supply side line off the lift pump and blow air through, should hear bubbles at the fuel tank. This is rare but have had it happen.

[AZtom]

John-
I don't see a water separator so I don't think it has one. Not sure how old the filter is. I haven't changed it and I bought the bus a year ago so it's prob time to replace it.

Ronnie-
I followed the fuel line and it looks like it goes to the lift pump first then to the fuel filter. I'll do the broom handle manual pump option. Last thing I need is something else to go out.

I ordered a new fuel filter so we'll see what that does.

I'm guessing if the filters not the issue then replace the lift pump?

[Ronnie]

Yes if not filters then lift pump most likely. Just remember the "wild card" being the fuel pickup in the tank, note not fuel pump just the tube inside the fuel tank.

[Dapplecreek]

And you might want to replace the lift pump with a stouter aftermarket electrical pump. I understand (reading, not experience) that the stock mechanical lift pump was prone to failure, which kills the expensive injector pump. (The fuel cools the injector pump: inadequate fuel from the lift pump causes it to overheat.)

[Ronnie]

The second generation lift pumps are great, it is the first generation diaphragm lift pump that can be trouble. So you should have the piston type lift pump being a 96.

[BlackJohn]

Is there any chance that might have a fuel solenoid on it? My 95 Cummins did so just wondering. They do fail without warning.
It would have a fuse or breaker for it I imagine. Just something more to check for you as you get to know your engine better.



John

[AZtom]

It does have the fuel solenoid. I can hear it click on when I turn the key. Just to make sure it stays engaged I put my hand under it to make sure and it stayed in place.

[BlackJohn]

Originally Posted by AZtom

It does have the fuel solenoid. I can hear it click on when I turn the key. Just to make sure it stays engaged I put my hand under it to make sure and it stayed in place.

Ok if you are sure of that then try priming the system with that solenoid energized. Still have to bleed air but should allow fuel to flow through the solenoid now.


Many 5-9's out there, so am surprised nobody has encountered this and knows the proper procedure to prime. Keep on trying. This is a great lesson for you in any case.



John

[Ronnie]

You can get prime up to the injection pump without the fuel solenoid on. What the fuel solenoid actually does is move the fuel rack in the injection pump to a no fuel position, so the injection pump elements (plungers) simply do not send any fuel to the injectors. Once you get fuel to the injection pump then the fuel solenoid must be on to bleed the injectors, and then you must crank the engine to complete this step. The fuel line at the injectors will need to be loose. then will be closed in turn as fuel appears. Wear safety glasses for this, please

However I am believing by what has been said he is not getting any fuel to pump to the fuel filter or injection pump.