4108 fuel injection pump - starting problem
Last year I did a lot of work on my engine, and after had trouble starting it. I spent hours looking for air in the low pressure side. The engine would after a while (10 seconds) start when cold but when hot refused to start, without bleeding. Once running it ran and idled well. No significant smoke of any color. Turn the engine off after an hour, and immediately attempt to restart failed.
I spent the whole winter fiddling with the system, and eventually after losing the engine 20 miles from home, did what I should have done and took the fuel injection pump off. It was leaking fuel from the main front seal. (the leak was not visible because the leaking fuel went into the timing gear
housing at the front of the engine. Another sympton that I should have picked up was that when bleeding and cracking open the injector line at the injectors and turning the engine it took a long time for fuel to squirt out.
I sent it in for testing. It required new seals
and a new head
. Interestingly when tested the fuel pressure was low on the injection side, but the cylinders were not damaged- just worn - after 25 years, so that when the fuel and pump heated up the clearances were not tight enough to create the necessary pressure to the injectors. The replaced head solved
the problem, and the pump tested out at 100%.
It was not easy to find a good company to do the work, however I found on the internet
a company called Oregon
Fuel Injection in Eugene. They sell (if in stock) rebuilt 4108 pumps with one year warrantry for $680. Because my pump needed a new head the cost was just over $1,000. The turn round after receiving the pump was two days.
The folks there are very helpful. Telephone # 1-800-452-5055, ask for Mark.
website: Oregon Fuel Injection, diesel fuel injection pump, turbo, injector and diesel performance product specialist.
By the way it is not easy to take off the pump. On the inside next to the engine is a bolt that needs a 7/16 allan key, and a very narrow space to get at it. I bought a key ($1.75 - about 3 inches long) and cut the elbow
piece off and fitted the longer part to a 3/16 inch socket (epoxied) for a 1/4 inch drive extension. You can use a 3/8 drive, but the space is very tight and a 1/4 inch is better.
Hope this post helps anyone who runs into similar problems. Moral of the story is that the low pressure side is not always the problem!