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???

might help if you give the engine make and model

Tinstar wrote: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???IF you had such a thing as a stuck fuel solenoid it would either be open or closed, it would not close when removing power if it was open when applying power if it did then its not stuck IF the engine actually ran when holding in the crank position and dies when key released then you have a faulty ignition wire or switch system

MountainAir05 wrote:might help if you give the engine make and modelSorry about that. It's a Cummins B5.9 (mechanical engine).

gutfelt wrote:IF you had such a thing as a stuck fuel solenoid it would either be open or closed, it would not close when removing power if it was open when applying power if it did then its not stuck IF the engine actually ran when holding in the crank position and dies when key released then you have a faulty ignition wire or switch systemFrom what I read, the fuel solenoid actually has two power wires going to it. One is a higher power to initially open the solenoid while the key is in the crank position and the other is lower powered to hold the solenoid open in the run position. I'm sure you're right about it not being stuck but what if the solenoid was not getting power after it cranked. The higher power wire gets power when cranking but when the key is released the lower power wire is supposed to take over holding it open. No power to that wire would allow it to close. Does that make sense???

Tinstar wrote:gutfelt wrote:IF you had such a thing as a stuck fuel solenoid it would either be open or closed, it would not close when removing power if it was open when applying power if it did then its not stuck IF the engine actually ran when holding in the crank position and dies when key released then you have a faulty ignition wire or switch systemFrom what I read, the fuel solenoid actually has two power wires going to it. One is a higher power to initially open the solenoid while the key is in the crank position and the other is lower powered to hold the solenoid open in the run position. I'm sure you're right about it not being stuck but what if the solenoid was not getting power after it cranked. The higher power wire gets power when cranking but when the key is released the lower power wire is supposed to take over holding it open. No power to that wire would allow it to close. Does that make sense???that's exactly why I said its a failed switch or ignition wiring problem I doubt the power would be different from crank to run and vice versa both would be 12-13 volts run a jumper wire to the fuel solenoid and see if it runs

My engine won't run | Good Sam Community

Tinstar
Explorer
Nov 05, 2017
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
Explorer
Nov 04, 2017
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
Explorer
Nov 04, 2017
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
Explorer
Nov 02, 2017
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
Explorer
Nov 02, 2017
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
Explorer
Nov 02, 2017
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
Explorer
Nov 01, 2017
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
Explorer
Nov 01, 2017
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
Explorer
Oct 31, 2017
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
Explorer
Oct 31, 2017
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.

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