deere 450B dozer engine power loss

mbavers · Jun 22, 2015

It is a 1974 model, non turbo. The dozer always starts easily and runs fine for the first 1/2 hr to 1 hr, then a gradual and steady power loss right down to engine quitting, over a period of about 5 seconds or so. I tried moving the throttle as the engine was dying; made no difference. I replaced both fuel filters but the same thing keeps happening. Yes, I bled the filters. After it quits, I can start it right up and continue working for another 1/2 hr to 1 hr. It seems like it must be a fuel problem, but why would it run so good for an hour or so, and why would it start right up again?? Air pre-filter is clean and last I checked the main air filter was good. Fuel looks good and 1st stage glass filter bowl is clean.

lantraxco · Jun 23, 2015

Take the fuel line off the tank at the shutoff valve, (close it first) then open the valve and check you have good flow into a container. If original there is a strainer screen screwed in the tank past the fitting for the shutoff valve, have to drain the tank to pull it out without flooding everything with diesel.

Check the return line from the pump back to tank, and also the check valve where the return line comes out of the pump, if it has debris in it, it's time for a pump repair.

mbavers · Jun 23, 2015

lantraxco said:
Take the fuel line off the tank at the shutoff valve, (close it first) then open the valve and check you have good flow into a container. If original there is a strainer screen screwed in the tank past the fitting for the shutoff valve, have to drain the tank to pull it out without flooding everything with diesel.

Check the return line from the pump back to tank, and also the check valve where the return line comes out of the pump, if it has debris in it, it's time for a pump repair.

I'm going to try that. I did notice when I changed the filters that the flow at the filters was more than the 1GPH that I burn, but will check flow at the tank and the return line.

repowerguy · Jun 23, 2015

As lantraxco said, the tank strainer is likely clogged or has a intermittent stoppage in the tank. On my old 450, I finally ran it low on fuel and vacuumed out the crud and then put a magnet in the tank for good measure. If you have algae, the best way to kill it is to drain the tank and steam clean the inside until hot and then let it drain dry, clean tank no algae!

Iron@Dirt · Jun 23, 2015

Sounds like fuel return check valve on pump top cover, try removeing it and run engine when it acts up, you will loose a little fuel but not to bad for a little while. mbavers tell us about homer and tv shows.

pittedmess · Jun 23, 2015

We had trouble with NAPA fuel filters...Seems the micron range was about 1. They would plug up without a pre-filter in about an hour and do the same thing. Back flush the supply line to the tank with compressed air as a quick check

guajilloweld03 · Jun 23, 2015

check fuel pump

mbavers · Jun 24, 2015

Iron@Dirt said:
Sounds like fuel return check valve on pump top cover, try removeing it and run engine when it acts up, you will loose a little fuel but not to bad for a little while. mbavers tell us about homer and tv shows.

If you mean those reality tv shows about the Kilcher's, they are greatly exaggerated. Those people live closer to town than I do; they have electricity, all modern conveniences, and drive into town for groceries and supplies. The "Deadliest Catch" series also greatly exaggerated. Now that I know how phony they are, I never watch any of them.

Iron@Dirt · Jun 24, 2015

mbavers, does Otto have a machine shop in Homer? We find Alaska shows interesting, different from south Lou., but believe them with a grain of salt. At least some of the shows are mostly clean compaired to regular tv. Harvey

mbavers · Jun 25, 2015

Iron@Dirt said:
mbavers, does Otto have a machine shop in Homer? We find Alaska shows interesting, different from south Lou., but believe them with a grain of salt. At least some of the shows are mostly clean compaired to regular tv. Harvey

Yes, Otto has a machine shop in town. I have used it a few times, but Otto is rarely there; I deal with Allen (I think that's his name).
Use more than a grain of salt.

Delmer · Jun 25, 2015

Regarding the original issue, you can use the priming lever on the lift pump to diagnose whether the fuel supply is blocked, and whether it is upstream or downstream of the pump. The pump feels different when it's pumping fluid vs air, pumped up vs pulling against a vacuum etc. I can copy and paste my explanation, but it's probably easier to disconnect the line on each side of the priming pump and use a can of fuel and your finger to alternately pump and then block each line and you'll quickly see the difference in the spring action of the priming lever.

I'll agree 100%, if you're going to take a guess, then the fuel supply being blocked (can that style collapse?) at the screen in the tank is 90% the best guess.

Don k · Jun 25, 2015

I had the same problem with my 450C and it was crap floating around in the fuel tank. Took the tank off and pressure washed the inside and now it is good.

Iron@Dirt · Jun 26, 2015

mbavers, we are going out to the country for a few days, would like to find out more about Alaska life later.

mbavers · Jun 27, 2015

OK, I think I misunderstood. You are talking about the return line from the injector pump? I looked inside my fuel tank and it is bright and clean, even the bottom is clean. I blew air into the fuel line at the fuel pump (not injector pump) and there is no blockage. There is no strainer where the fuel line exits the tank, and my parts book does not show one. I replaced the fuel pump. Same thing happens. I will look for the return line from the injector pump and the check valve. Curious thing is, whenever the engine quits I just wait a few seconds and restart and get back to work for another 1/2 hour or so.

mbavers · Jun 27, 2015

mbavers said:
I'm going to try that. I did notice when I changed the filters that the flow at the filters was more than the 1GPH that I burn, but will check flow at the tank and the return line.

OK, I think I misunderstood. You are talking about the return line from the injector pump? I looked inside my fuel tank and it is bright and clean, even the bottom is clean. I blew air into the fuel line at the fuel pump (not injector pump) and there is no blockage. There is no strainer where the fuel line exits the tank, and my parts book does not show one. I replaced the fuel pump. Same thing happens. I will look for the return line from the injector pump and the check valve. Curious thing is, whenever the engine quits I just wait a few seconds and restart and get back to work for another 1/2 hour or so.

R.D.G013 · Jun 27, 2015

mbavers said:
OK, I think I misunderstood. You are talking about the return line from the injector pump? I looked inside my fuel tank and it is bright and clean, even the bottom is clean. I blew air into the fuel line at the fuel pump (not injector pump) and there is no blockage. There is no strainer where the fuel line exits the tank, and my parts book does not show one. I replaced the fuel pump. Same thing happens. I will look for the return line from the injector pump and the check valve. Curious thing is, whenever the engine quits I just wait a few seconds and restart and get back to work for another 1/2 hour or so.

M AKE SURE THE FUEL FILLER CAP IS VENTING TO THE Atmosphere, if its not u will get a vacuum in the fuel tank as your fuel is used.

mbavers · Jun 27, 2015

R.D.G013 said:
M AKE SURE THE FUEL FILLER CAP IS VENTING TO THE Atmosphere, if its not u will get a vacuum in the fuel tank as your fuel is used.

That is an definitely possibility. I can't believe I didn't check it. Thanks.

lantraxco · Jun 27, 2015

That's a typical symptom of return line or return check blockage, can't be sure until you check it though. There's a fiber drive ring in the pumps that eventually begins to come apart and the fragments will plug up the return.

mbavers · Jul 5, 2015

lantraxco said:
Take the fuel line off the tank at the shutoff valve, (close it first) then open the valve and check you have good flow into a container. If original there is a strainer screen screwed in the tank past the fitting for the shutoff valve, have to drain the tank to pull it out without flooding everything with diesel.

Check the return line from the pump back to tank, and also the check valve where the return line comes out of the pump, if it has debris in it, it's time for a pump repair.

So far I have blown clear all fuel lines, replaced fuel transfer pump and fuel filters, taken return line check valve out of injector pump and it seems clean and normal, and finally I completely bypassed the fuel tank by installing a temporary tank on the back of the dozer and hooked it up to the main fuel line. Fuel is clean and vented properly. Air has been properly bled. Engine runs fine for 15 to 20 minutes then dies, same as before. Would a bad injector pump allow engine to run 15 minutes before quitting? Engine does not run rough, miss, or hesitate, it just idles down and quits. HELP

lantraxco · Jul 5, 2015

1) Are you getting fuel flow out of the return? Is it possible the line is plugged somewhere along the top of the injectors, all those short hoses and tees? Maybe take it off at the check valve and blow back through it.

2) There should be a strainer in the pump head, never heard of one plugging but? #8

deere 450B dozer engine power loss

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