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1994 Ram 3500 5.9 12v cummins
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Discussion Starter · #1 ·
I recently bought this truck n I'm new to diesels. So when I bought it I had a hard time trying to get it going but once I got it warm it would crank good. I bought it in Houston so I drove it back.. 3 hours on the trip back it turned off on me when I would press on clutch but as soon as I would put it back on gear it would come back to life. I drove it back to San Diego everything was fine while I was cruising just hard keeping the engine on while going tru gears to fuel up. I did notice If I kept my foot on the gas pedal it would stay on sometimes. I haven't been available to keep it on since I parked it. I been working on it doing some research I replaced the fuel filter, delete the fuel heater, ran a 3/8 fuel line from the lift pump to the hard line the comes from the diesel tank. I think it's something related to the fuel since I remove the shutoff solenoid n put a spring on it to keep the diesel fuel supply open all the time. When I finally crank it it dies.. today I kept my foot on it n it idle at 1000 rpms n idle for 15 minutes before it just stalls n tried to crank it n it didn't crank up. I think is air or the injection pump not delivering fuel? Feels like it loses prime. I will add that it would idle at very low rpms when I got it like very close to the 500 rpms idk if that helps.. any suggestions I'm open to it like I said I'm new to diesel.. Also I will add that is leaking oil from somewhere on gearbox which I'm going to fix as soon as I can keep it on.. hope to hear back from someone thank you in advance
 

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Do you have a fuel pressure gauge on it, it's a good troubleshooting tool?

If you think it's a air in the fuel system problem all you have to do is crack open the bleeder for the filter after the truck has sat for about a half hour not running. Manually pump the LP and watch to see if any air bubbles come out the bleeder.
 
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1994 Ram 3500 5.9 12v cummins
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Discussion Starter · #4 ·
I cracked it n press the Lift pump 3 times no bubbles just diesel.is there any other sensor or solenoid that would turn the engine off? Or should raise the idle rpms now?
 

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Only the fuel shutoff solenoid shuts it off.

The 94 and 95 injection pumps have issues with them going bad and if it quits running you poor ice cold water over it. If it starts back up and runs good for a while again it's a sign the IP needs rebuilt.
 
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1994 Ram 3500 5.9 12v cummins
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5 Posts
Discussion Starter · #6 ·
Ok so I crank it n it stayed on but I had to keep my foot on the pedal because if I let it under 1000rpms it stalls. I do remember putting a brand new spring on the idle thing cause one time the foot pedal got stuck on high rpms n that fix the pedal from sticking but could it be that it added more oem spring tension than it needed? I bought this spring at a hardware store. So it's not an oem spring replacement could that be the reason it stalls?
 

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The spring won't make it stall unless the idle is dropping below around 600 to 700 rpm's. The normal idle speed is around 800 to 900 with the AC on.
 
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There could be trash in the fuel tank blocking flow irregularly.
 
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Is there a intact steel wire over the governor spring cap? Someone could of installed higher revving governor springs and did not install them correctly.
 
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If it isn't a screwed up gov spring mod, install a fuel pressure gauge so you will know if the injection pump is getting steady pressure or if it starves for fuel when your problem occurs.
 

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Try two things:
1. Adjust the idle screw. You mentioned putting a spring from a hardware store on as a replacement. Hopefully it was one of similar size and tension?
2. Install a new overflow valve. When I got my 96 12 valve 2 years ago from the original owner, it had sat for a while. It had very similar low RPM stalling issues at start up. I put a new overflow valve on and it started like a new truck and idled perfectly. I did have to adjust the idle screw after installing the overflow valve. Springs lose tension over extended periods of time and need adjustment. Start there and let us know how it goes.
Here is a link to a new overflow valve. I am not associated with this company but have ordered from them before. They have good customer service and quick shipping.
 

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All of the Bosch pumps have their share of plunger failures, I’ve had 180 and 215 pumps fail. Basically the barrel warps or cracks, causing the plunger to stick in the barrel. This causes the fuel rack to stick and most of the time they seem to stick in the low idle or no fuel position, causing the truck to stall or have random throttle events.

depending where the plunger sticks in the bore you can usually hear a tapping sound from the pump as the follower hits the cam lobe on the way around

if you’ve got any amount of fuel pressure and the fuel shutoff solenoid is in the ‘on’ position and it won’t start or dies while still maintaining fuel pressure. You’re looking at a plunger or governor failure
 
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