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Discussion Starter #1 (Edited)
I have a thread in this section, 4BT Reviva, however I felt that this topic was important enough to be a stand alone thread if for no other reason than to help someone avoid what I have been through.

My 4BT Reviva is a 1996 rebuilt engine, 130 HP, that saw very little use prior to being cut from a step van chassis. I purchased the engine sight unseen based on the discussion I had with the owner who was selling it. Bought for $1,500 totally complete less cooler and radiator.

I installed the engine in a 1998 Trojan 1500Z wheel loader to replace a Deutz F5L912. Cutting to the chase, after the engine was installed, a rubber hose was used as the pickup line from the tank to the lift pump. Engine fired and ran for 20 seconds or so. The vacuum created by the lift pump collapsed the hose. Replaced the hose with a 3/8 steel line with 3" of hose at the tank and at the lift pump. Fired the engine and it ran for about 3 minutes and died.

The lift pump prime plunger did not feel like there was any resistance. Opened the bleed port on the injection pump. Started to prime the system again. NOTHING. Suspected the lift pump was defective. Removed the filter .... slight dribbles. Has to be the pump !!!! The injection pump and the entire fuel system was dry. Had an electric pump so I hooked it up at the lift pump, purged the air and tried to get fuel to the injection pump. Had flow but not a heavy stream as I expected because it was relieving to the tank return. Fired the engine and ran. End of problem. Drove the loader 6 miles from the shop to a property where I needed the loader. No issues at all during the drive.

Started to work the machine hard and fully loaded. Engine stalled and died again. Same issue as before, fuel system was completely dry. Bottom line, the injection pump was not getting any fuel. I knew the electric pump was working. Disconnected the fuel line at the lift pump and the electric pump was really flowing. Problem had to be in and around the connection at the lift pump.

Disconnected the electric pump and unscrewed the 1/2" IP X 1/4" reducer fitting from the lift pump body. Inside the fitting attached to the lift pump is a debris screen. When I examined it, I could not see daylight through the screen. The material trapped by the screen was like heavy tar. Finally got it cleaned up and re-installed the body and screen back in the pump. Also removed the electric pump and reconnected the steel fuel line and used a compression fitting on the tube with 3/8" and 1/4" MIP to the body. This was to eliminate one more possible leak.

Opened up the injection pump return bleed port and started priming with the original lift pump. Took a while to bleed the air out to that point, but at least I new the OEM lift pump was good. Next I bled the injectors. Because the pump was dry, it took a while to purge the air. The engine fired and ran for 20 minutes. Took it out and put it to work with no more problems.

Lessons Learned

1. If the engine has sat for a while and the fuel system was not capped, there is a very strong possibility that the entire fuel system will be dry and any debris that is in the system will also dry out.

2. When an open system is allowed to dry out, it could cause the injection pump to seize and loose debris to become concrete like or as in my case like tar.

3. Pin point where you problem lies, don't start changing parts before you know where the "real problem" is located.

4. If your engine starts and dies, start at the very beginning, at the tank. Verify that you have no air leaks up to the lift pump. The more hoses and clamps you have, your chances of a leak just went up by a factor of 10. Buy a small squeeze pump and some clear tubing and connect it to you fuel supply line. Prime the line with the squeeze pump. Verify you have no air leaks or fuel leaks. If all checks good, time for the lift pump.

5. This was my first go around for a 4BT. I assumed that the lift pump fed the fuel filter with nothing in between. The fuel filter was changed prior to firing the engine so I knew the filter was good. If you don't have fuel at the out flow from the filter the problem can only be the fuel filter or the lift pump. In my case I was suspecting a defective lift pump not allowing fuel to pass through it. It was just by chance that I saw some debris in the pump fitting and decided to remove it. Cleaned and re-installed and problem went away. If I had decided to replace the pump, it would have cured the problem as well, but at a cost of many $$$$$$.

6. If you identify a problem with your fuel system, try to pin point the issue and then trouble shoot that until it is resolved. There may well be other problems, however work your way up steam one step at a time. Troubleshooting by changing parts can be very expensive.

Paul
 

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That little debris screen often causes trouble. If people would just maintenance it occasionally, it would cure a lot of ills. When you couldn't get any resistance on the lift pump there is another thing that causes that. If the cam stops at a certain position, the little hand pump button doesn't work. Those pumps create pressure on the outward stroke. Also, your electric pump probably wasn't providing enough pressure for the P 7100. It needs in the 25-30 lb range. As you found out, a clean fuel system is mandatory. A fuel pressure gauge is a very worthwhile item to have on the engine. It will alert you to a low pressure problem like a clogged fuel filter or weak lift pump.
 
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