In the past week, I have noticed my new to me Cat 426 losing power when going up hills or digging under load. I suspected clogged fuel filters so I removed the two canister filters as well as cleaned out the screens on the fuel pump and injector pump. The old filters were very dirty and all but stopped up. I have no idea how it was still running at all in that condition. Anyway, I replaced both fuel filters and proceeded to try and purge out the air and prime the lines. My manual lever on the fuel pump does not seem to be pumping so I've had to try priming the whole fuel system by cranking the starter in short intervals. So far I have still not been able to get the entire system primed which also means I can't get the backhoe to crank now. I was wondering if anyone has ever installed an electric inline 12V fuel pump to use for priming. Once system is primed, power can be turned off and just let the mechanical pump supply fuel to the injector pump and then on to the injectors. I could either install a toggle switch or just clip on alligator clips to use inline pump when needing to prime system. I do know that I use to have a 3 cylinder diesel motor on a mower that had an inline electric fuel pump which made it very easy to prime in just a couple minutes. Just turn key, open bleeder valve and wait for pump to pump fuel throughout fuel system. Only thing is, that diesel did not have a mechanical fuel pump. Will the original sock mechanical pump have problems pumping fuel through an inline electric pump? Any other ideas?? Thanks.
Have you tried the prime lever after bumping the motor over? It has to be on the lobe of the cam so you can prime it. Did you pre-fill the filters before you swapped them? Some say not to but I generally do. You may have to crack a couple lines loose at the injectors and bleed some air out. I've also seen the electric shutoff solenoid act up as well as the hand primer on the filter head draw air and make them run like crap or not at all. Yours may or may not have the primer on the filter. They can try your patience sometimes....
on the injection pump there is 2 little 5/16 bolts bleed all the air out of them and then crack the injectors open. IT should run after this.
Be real careful with those 5/16 bolts. They are needle valves screwed into the outer piece that's a 7/16 wrench I think. Hold the 7/16 and then loosen the 5/16 locking nut. Then loosen the needle valve and bleed. Bottom one first then the top. The outer 7/16 is screwed into soft aluminum, easy on that or you'll have a leak. And yes, that 4/236 is a SOB to bleed. Joe H
I did not prefill the filters. These are not spin on filters and I saw no easy way to prefill without losing all the prefilled fuel before getting the canister back together. I tried the prime lever numerous times after several cranks of the starter. Made no difference at all.
I did try this starting with the bottom bleeder first then the top bleeder. I'm trying to do this alone and very hard to tell if all air is out from the drivers seat working the key. This is the reason I'm asking about the possibility of using a 12v inline electric fuel pump. Would make it so much easier with me able to stand at the injector pump and close off bleeder valves while still pumping fuel. Only thing is I'm not sure the mechanical pump will pump through the inline pump to keep motor running after it is cranked.
Your going to have to run 1 or the other.. The mechanical pump only runs about 7psi MAX.. if working properly.. & that's a big IF.. I suggest, if working alone, loosen the bleeder in the inj. pump by the name plate.. Use some shop air & pressurize the fuel tank SLIGHTLY, to force the fuel thru.. Once the screw is wet, tighten it.. THEN loosen all the lines AT THE INJECTORS & spin the engine.. wait till you get fuel AT THE INJECTORS & tighten.. & off ya go.. The thing about those filters you replaced, IF you put the top oring ON THE FILTER, it'll NEVER RUN.. The oring HAS TO GO, UP IN, THE FILTER HEAD.. NOT ON the filter.. I'll bet ,if you revisit the orings, you'll find your problem.. good luck.. TPG
I've got a perkins like that in a allis forklift. I have to loosen injector lines after changing fuel filters to get it to run. It just takes a while to get the air out. I wouldn't put a 12v inline in it, why complicate things.
Sounds to me like your lift pump is at fault. Does the priming lever just feel loose through 360* crankshaft rotation? Low fuel pressure could have been the cause of your low power issue. You can disassemble these lift pumps, wouldn't take long then you could rule it out. They are cheap as long as you don't buy it in a Cat box!
my telehandler has the 4.236 perkins and I bleed it my self. I normally run back in forth till i got the air out. A charger on the battery helps a lot as well. Try finding a helper to crank the motor over while you work on the fuel system
Yes, I had a customer do this to the strange little Perkins filter and it would not run...I assume this unit has that type of filter. There is a nice little groove between the filter and some part where you can stuff one of the square cut rings but all it does is block the fuel.
Those filters can mess you up good. If they're blocked the pump will feel like it's not pumping because it's not pumping if the pressure is built up. If you're pumping air, it WILL feel like it's pumping. Take both lines off the pump and use a can of fuel to see if the pump is working, it should prime and squirt almost immediately. Then you can hook the outlet back to where it came from and see how it feels when it pumps the pressure up. There's no reason to add another pump, it will prime easily when you figure out what's wrong now. And it won't prime with two pumps if you don't fix what's wrong now. (most likely the transfer pump is not the issue,but that's easy to test)
I'm used to seeing the honeycomb style filter like the first pic, you're figuring he's got this other style (second pic) and put the sealing ring in the groove of the filter, instead of in the filter head. Interesting!
All I can say is any manufacturer who doesn't have the sense to use a normal spin on can... Well you know the rest
I went a head and installed a $42.00 inline electric fuel pump. Had backhoe primed and up and running within 5 minutes. Sooo much easier now. I just used the electric pump to bleed air and then cranked engine and ran with stock manual fuel pump. Most all other Cat backhoes I have seen only had 1 fuel filter. Mine has a fuel filter just before the fuel pump on right side of engine and then another one just before injection pump on left side of engine. Luckily I had no issues with the filter o-rings this time but I will probably leave the top ones off on next filter change since they are a PITA to put on correctly. Thanks for everyone's help!!
I carry an electric pump with me but I haven't used it in a long time. I also have a drill pump for doing oil change pump outs. Sometimes I find that is the easiest way. Disconnect the line at the last easy place and then suck the fuel through with some force until it gives a good stream, then reconnect and usually the fuel is close enough it will start.