I have an 89 Cat 426 Backhoe that I let sit for a couple years without cranking. I drained the fuel tank, changed the filters, put in new clean fuel, and bled the injectors. Trouble is that it will crank and only run for about 10 seconds before dying. The injection pump has two bleeder valves and if I remove the top bleeder valve, the engine will run without dying but of course it sprays out a continuous stream of fuel out where the bleeder plug goes. Once I put the bleeder valve back in, the engine dies and shuts off in about 10 seconds. Any ideas on what would make a Perkins 4.236 engine run without the top injection plug installed but not run if the bleeder plug is in? Could in possibly be a blocked return line back to the fuel tank and with removing the bleeder plug it allows the excess full to exit the fuel system through the injection pump or do you think it could be an issue inside the injection pump? I did not have this issue at all before it sat for a couple years. Thanks!
With Cat the serial number is important. I bought a Cat 426 of the same vintage. Main issue was it started and ran for a short time and would not restart until you bled the system. The guy I bought it from replaced all kinds of fuel system parts and I got it cheap. The fuel return was blocked in the fuel tank.
Blow out the "bleeder valve" with brake cleaner and compressed air. Does the bleeder valve leak fuel if you start it with the bleeder valve but no return lines hooked to it?
I have not tried starting it with the return line unhooked yet because I wasn’t sure which one was in-fact the return line. Where is the best place to disconnect the return line from?
Exactly what is the best way to blow out the bleeder valve? This is a Perkins 4.236 engine and the injection pump has a lower and upper bleeder plug? This is not my injection valve but looks just like it only mine is Cat yellow. If that top bleeder plug is removed then the engine will run. If the plug is in, then the engine will run for about 10 seconds then die.
This might give you some idea.
Sorry, I was confused. The inlet is the rear between the lines to the injectors. The fuel return is the line at the front close to the engine timing cover. Remove that line, see if it starts and runs and leaks fuel. If it doesn't, remove the fitting and try again. That's the fitting I was thinking of, different pump though.
Thanks a bunch. It did help me.
Ok… I loosened the return line coming back from the injectors to the filter housing. It run like a champ but sprayed fuel every where so there must be a blockage between the filter housing back to the tank. I am having trouble getting a wrench on the return line where it goes into the tank. I’m wondering if I could blow compressed air through the line to blow the blockage back into the tank instead of removing the line to clean out. Thanks!
Shouldn't hurt anything to blow as long as it's just that line, no filters, and remove the cap from the tank. It might not work, but then you try something else. Grease gun filled with oil and threaded adapters?...
@Link On my 426 the line going into the tank was clogged with sediment, rust or dirt, not sure which. I took the tank off the machine and had to use a coat hanger and compressed air to clear the line into the tank. No way I could have cleaned it without removing the tank. It took longer to clean all the crud off to get to everything than it did to remove it. I drained the fuel out before I dropped the tank. There is a drain for the fuel tank. It is on the side facing the rear tire. Remove that drain the fuel. I used a floor jack under the tank then removed the 4 bolts holding it to the frame. I lowered it down an inch or so to make it easier to get wrenches on the lines where they connect to the tank. You need to remove the clamps for the hydraulic lines and disconnect the fuel sender. There is also a vent. Make sure that vent piece is clear otherwise that can cause issues too. The vent looks like a flying saucer and is on the end of a pipe and tuck up under the cab. I have a cheap borescope I paid $30 for that allowed me to look inside my tank. It was pretty rust free. Not bad for a 30 year old tank.