Perkins 4-108 Erratic RPM
Date: September 4, 2003 I have an E40 with a Perkins 4-108 engine. I've had it 11 years. I was having symptoms as you describe...erratic rpm. The engine would run OK for a time then the rpm would drop or sometimes increase. Sometimes hard to start. I made numerous searches for air in the fuel lines, clogged filters, fuel pumps, etc. I finally found it was a worn or malfunctioning high pressure fuel pump. Finding the problem was just the beginning. On a 4-108, getting the pump off is a super bear of a job.(it could be described as a hideous! job) I hired a very skilled diesel mechanic who can bend into contortions and have magic finger dexterity, but it still took him hours to get the pump off. He did give me some very bad advice. He said a pump shop is a pump shop...a local shop that works with trucks, busses, superchargers, can do as good a job as a specialty shop. Bad advice. He took the pump to the local shop. It cost a fortune. He worked to get the pump back on (worse than taking it off). The engine was the same as before. He took it off a 2nd time and had the local pump shop redo the pump. He put it back together the 2nd time and to his dismay...and mine the engine did not improve at all. The mechanic was certain the problem was the High pressure pump...nothing else. He took the pump off a 3rd time. This time I insisted on taking the pump to a "Precision Instrument Pump shop" in Mobile Ala. They installed an overhaul kit, tested it, and adjusted it and guaranteed it was like new. The mechanic reinstalled the pump for the 3rd time...and the engine runs like a new supercharged dynamo and has given me no other problems. The mechanic was chagrined. The problem with a small local pump shop is they do not have extensive "test stand" equipment. They simply install an overhaul kit...and that's it! A big specialty operation has all the computerized specs of your engine and the pump. They install the pump on the test stand and run the hell out of it, to all the specs and demands that your engine will require, and adjust pressures and limits of the pump. The shocker is that the big precision shop is much cheaper than the local shop! I had to threaten to sue the local shop, but they did give the money back they had charged. Fortunately the mechanic charged only for one take off/put back on.
From: Jim Parks RIPTYD97@aol.com
If you find the problem is the high pressure pump, be sure to take it to a good repair shop.
