My engine won't run

[Tinstar]

I need some help with a 1994 Allegro Bus. We're trying to start the engine and not having any luck. The engine cranks over fine but no start. It has not been started in several months. It has run fine for years prior to this problem.

Originally I could turn the key to the crank position and the engine would start and run AS LONG AS I HELD THE KEY IN THE CRANK POSITION (I did not let it run but a few seconds with the key in the crank position). As soon as I released the key to the run position the engine would immediately die. I believe that was due to a stuck fuel solenoid. My theory is; It would hold open while cranking but as soon as I released it to the run position, the fuel solenoid would disengage thereby shutting the fuel off and it would die. Anyway, I went underneath and messed with the fuel solenoid (exercising it checking the wires). I know it is holding in the run position BUT now it won't start (it does still crank). I am thinking I lost prime while it sat and I'm not getting fuel to the injectors. I've tried using the lift pump but still no start. I have pumped the lift pump dozens and dozens of times.

I am now thinking about cracking one of the banjo nuts at the injector and crank it over. I think I should get a fuel spray while cranking it over with a banjo nut loosened.

Before I go down that road, does anyone have any other suggestions and what do you think of my theory. Am I chasing the right solution???

[Tinstar]

11178adm wrote:
a quick and dirty way to prime is to loosen the fuel line as close to the injection pump as possible and with a with a air blow gun put air pressure in the tank through the filler pipe using a old towel to seal the air, don't get too much pressure in the tank 3 to 5 psi will do. have an assistant tighten the line when you get clean fuel with no air bubbles, it should start after that. also check for fuel leaking any place between the tank and the fuel lift pump.
hope this helps

Thanks 11178adm, That's the same instructions the diesel mechanic gave me. I'll have some help in 3 or 4 days. I'm going to give it a try then.

[wolfe10]

11178adm,

Well said.

I will add that fuel lines between the tank and lift pump, because they are on the SUCTION side of the system, can fail by leaking air IN, as fail by leaking fuel out.

[11178adm]

the 5.9 and 8.3 cummins with the bosch p series injection pump use a shut off solenoid that has a pull in coil and a hold in coil. the hold in is hot with the key on, the pull in is hot only in the start position, if the pull in side is used to run the engine it WILL burn out the solenoid after a few minutes. the primer is made as part of the fuel lift pump, as stated in a previous post if the primer pump does not have any resistance it has lost prime. if you have access to air pressure a quick and dirty way to prime is to loosen the fuel line as close to the injection pump as possible and with a with a air blow gun put air pressure in the tank through the filler pipe using a old towel to seal the air, don't get too much pressure in the tank 3 to 5 psi will do. have an assistant tighten the line when you get clean fuel with no air bubbles, it should start after that. also check for fuel leaking any place between the tank and the fuel lift pump.
hope this helps

[Tinstar]

It's not the VP44. I believe it's a Bosch. I have talked to a couple of diesel mechanics. I'm going to try his suggestions here in a few days. He described in detail how the fuel flows and routing from the tank to the cylinders.

[wildmanbaker]

If you have a 94, it does not have the VP44, computer controlled injector pump, but a manual. Depending on the actual rear of the engine, you could have a lift pump, or a manual pump run of the engine. There are several things you could do to get it running, but if you are not diesel savvy, you should get the engine size, year and chassis information, a go to a truck service center and ask to talk to a tech about your problem. They may give you enough information to get it running. That is how we learn. Best of luck.

[wildmanbaker]

If it has a VP44 injector, the pump will only run for about 10 seconds, if the engine is not running. If it is the 5.9, the fuel filter should be near the engine. It will have several plugs in the top for testing. Loosen the plug closest to the injector pump, and cycle the key on and off until you get fuel spray at the plug.

[gutfelt]

Tinstar wrote:

gutfelt wrote:
with key on you should hear the prime pump; maybe the prime pump is not activating for the same reason the fuel shut off solenoid is not on my ISL its right on or near the engine as I can hear it running when keys turned on

As best I can tell, there is no electronic fuel pump and the only one is the mechanical pump at the lift pump. I got shut down by rain so when I can I'll take a fuel line loose at the pump and crank it over. Hopefully, I'll get fuel flow.

The lift pump is used on many Cummins engines, but most often problems with the pump are associated with the 5.9 ISB. This pump is used to transfer fuel from the fuel tank to the injection pump (known as the VP44 injection pump). The lift pump runs at all times when the key is on.

[Tinstar]

gutfelt wrote:
with key on you should hear the prime pump; maybe the prime pump is not activating for the same reason the fuel shut off solenoid is not on my ISL its right on or near the engine as I can hear it running when keys turned on

As best I can tell, there is no electronic fuel pump and the only one is the mechanical pump at the lift pump. I got shut down by rain so when I can I'll take a fuel line loose at the pump and crank it over. Hopefully, I'll get fuel flow.

[gutfelt]

Tinstar wrote:
Does anyone know where the fuel pump might be and how to get to it? It's probably inside the tank but I don't know. I removed the filter and cranked the engine over. I am not getting fuel at the outlet when cranking. The filter is about 1/3 full so I definitely do not have prime. I suppose I should be getting fuel at the filter when cranking the engine.

with key on you should hear the prime pump; maybe the prime pump is not activating for the same reason the fuel shut off solenoid is not
on my ISL its right on or near the engine as I can hear it running when keys turned on

[Tinstar]

Does anyone know where the fuel pump might be and how to get to it? It's probably inside the tank but I don't know. I removed the filter and cranked the engine over. I am not getting fuel at the outlet when cranking. The filter is about 1/3 full so I definitely do not have prime. I suppose I should be getting fuel at the filter when cranking the engine.

[Tinstar]

wildmanbaker wrote:
JC, when you pump the primer lever, does it get hard and not pump anymore? If it doesn't, then locate the last filter before the injector pump and loosen the pressure tap fitting and bleed out the air.
Good luck.

No, it stays soft to the touch other than the spring in it.

For others, the fuel solenoid is working now. I don't think it was before. Hopefully, if I can get it primed and started, I will know for sure if the solenoid is working properly. My luck will be the solenoid is working but it still dies after releasing the key to the run position. I'm going to work on it again tomorrow.

[wildmanbaker]

JC, when you pump the primer lever, does it get hard and not pump anymore? If it doesn't, then locate the last filter before the injector pump and loosen the pressure tap fitting and bleed out the air.
Good luck.

[Ava]

Once you figure out the electrical issue you need to open the banjo fitting at the top of the fuel filter and perhaps a couple of the injectors before pumping the lift pump to get it primed again.
On the electric side, my 94 Cummins 5.9 has a solenoid mounted on the left upper side of the engine bay that has to have power before the starter circuit will operate. There are other wires there so this might be another place to check for power. Good luck

[Flan]

You can manually hold the lever in the up position while cranking as well. It does have a hold and a pull coil, relay or solenoid may be bad.