I use my B7500 every couple days usually, when I got on it the other day it wouldnt rev past 2,000 rpm. I used it and tried rev'ing several times and it would always stop at 2,000 rpm. I took the covers off and verified the linkage was still going all the way wide open and it is. My next step is change the fuel filter again. A couple months ago I got a tank of bad diesel. Since then I drained the tank and changed the filter and then it ran perfect. Already went through another tank of diesel with no problems. Any ideas?
B7500 wont rev past 2,000 rpm
- Thread starter minytrker
- Start date
Possibly there is algae growing in the tank from the bad fuel that is limiting the fuel flow or a piece of trash in the tank??
You could try wide open throttle and look to see if the fuel filter is staying full.
You could try wide open throttle and look to see if the fuel filter is staying full.
This^, plus-
There can also be algae residue, even if you used something to kill it, that can migrate to the pickup tube or the filter, and clog them. I would say that going through the fuel system prior to the pump is the definite first step.
You can be getting fuel, but it can be restricted and starving at high demand.
I unhooked all the fuel lines and drained about 2 gallons of diesel out and changed the fuel filter. The filter looked pretty good, had just a hair of trash in it. All the lines had diesel flowing out of them like crazy, none seemed restricted. The tractor revs to 2200-2300 ( thought 2000) rpm and stops like its at the rpm limit. It does it In neutral or while driving.
Grouse Feathers
New member
Lifetime Member
Equipment
BX2370, FEL, Snowblower-BX5455, Homebuilt Forks, LP RB1560, LP GS1548
Does it hold the speed at 2200 - 2300 when you put a load on the tractor. If the fuel increases to maintain rpm when loaded its probably a linkage problem. If the speed drops off when you put a load on the tractor then its a fuel problem.
alansz400
New member
Equipment
B7500. FEL, Piranha tooth bar, box scraper, post hole digger, 3 pt. bucket
Daren Todd
Well-known member
Lifetime Member
Equipment
Massey Ferguson 1825E, Kubota Z121S, Box blade, Rotary Cutter
Using the hand throttle, run rpm's up all the way and see if the rocker is hitting the set screw on the injection pump. If the rocker isn't hitting the set screw, then there is an issue with the linkage somewhere.
You can also disconnect linkage from the rocker, and move the rocker by hand and see if it allows the rpms to go higher if it's not hitting the set screw. That will also tell you if you have an issue with the linkage or internally in the injection pump.
Last, if it is hitting the set screw for max high rpm, check the set screw and see if it's loose. If it is, then vibration could have caused it to turn in causing you to lose max rpm.
You can also disconnect linkage from the rocker, and move the rocker by hand and see if it allows the rpms to go higher if it's not hitting the set screw. That will also tell you if you have an issue with the linkage or internally in the injection pump.
Last, if it is hitting the set screw for max high rpm, check the set screw and see if it's loose. If it is, then vibration could have caused it to turn in causing you to lose max rpm.
The air filter is brand new, I also pulled the air filter out and it didn't change the rpm any. I checked the linkage and both the foot pedal and hand level are making the linkage go all the way to the stop. The linkage adjustments look like they have never moved since everything looks equally dirty. There isn't any clean or shinny part indicating it had moved recantly. I used a box blade and the front end loader and also drove it down the road and it maintains 2300 the whole time. It just won't go to 2600 like it did last week.
Grouse Feathers
New member
Lifetime Member
Equipment
BX2370, FEL, Snowblower-BX5455, Homebuilt Forks, LP RB1560, LP GS1548
I t doesn't sound like a fuel or air problem if you can maintain rpm using a box blade and loader. Maybe the linkage is sticking or bent? I don't have a B7500 just a BX so not much more I can suggest.
This is scraping rock bottom, but any chance the tach is screwy? Does it sound at "2200" like it is working normally?
Does your tractor have a foot activated accelerator pedal on the right side? If so, maybe it's got something out of adjustment or jammed and not letting the linkage move the full amount.
Did you check the fuel pickup in the tank?
That may not be your problem, but since you did have an algae issue, you need to make sure that all debris is gone. Small pieces will float around, collect, and build up to create a barrier/clog.
That may not be your problem, but since you did have an algae issue, you need to make sure that all debris is gone. Small pieces will float around, collect, and build up to create a barrier/clog.
It's hard to say if the tach is correct. It seems correct. Hooked up my 4 ft shredder and shredded 1 acre and rpm never dropped any whole time. I checked the linkage again, both foot feed and hand throttle are going all the way to the stop.
Does these have injection pump?
Does these have injection pump?
I am wondering if the fuel rail in the injection pump is binding or not reaching full stroke? I am not an injection pump tech. I would contact your local diesel injection pump service center and ask them about it.
Tell them make model and that is a cassette style pump. They may want you to remove the pump so they can put on to a test stand to run it. Don't loose any of the shims under the pump body. This will change the pump timing if you do!
Pat
Tell them make model and that is a cassette style pump. They may want you to remove the pump so they can put on to a test stand to run it. Don't loose any of the shims under the pump body. This will change the pump timing if you do!
Pat
Years ago I worked on an L3000, IIRC, had similar issue. The governor has a pair of springs that pull the pump rack. One of those springs was broken. Replaced, all was well. I think it would run about 2100 RPM max but it wasn't low on power that the owner complained about, just said it wouldn't run rated RPM and of course the blade speed on his finish mower was way down.
Called injection pump service place here and talked to them for almost 30 mins. They felt like it was not the injection pump based on everything I tried and how the tractor was running. They told me to test the PTO RPM so I ordered a $20 tool to test the PTO RPM. If it 540 rpm then its going to 2600 rpm.
I will check all over that closely. I checked it for bent or loose linkage but didnt lpay attention to any springs.
Tested the PTO RPM today. When WOT (tach showing 2300 rpm not 2600) where the 540 PTO line is at the PTO is at 542 RPM. So if the RPM is at 542 rpm then the tach must be off correct?
Not necessarily, you can check in an operator's manual for that model to see what the rpm equivalent of 540 pto is. On my L3560 540 is at 2426, but on an L6060 it is 2403 for example. WOT on mine is 2600.
The dash has a line at 2600 rpm saying 540 PTO. So I going off that assuming that if my PTO is at 540 rpm then the engine must be at 2600 rpm and not the 2300 rpm indicated by the tach.