TZ25DA Losing RPM's ~Help!

[newholland4me]

Ok, first let me say that I am a girl so go easy on me. This tractor was purchased new April '07 (has 90 hrs.) and has been just great right along. It has a Woods finishing mower on it. I took it out to mow the front field which is very low and dry right now so no real load on engine. I mow for approximately 45min. and then RPM's start dropping off rapidly for no apparent reason. I immediately disengage the mower and drop the throttle and engine is shuttering still. I have to turn off engine and wait a few minutes then restart. I will still have mild shuttering but as long as I keep it at around 1000 RPM's and let it just sit it will usually clear up after a while. Takes a few tries at times. The longer I wait to restart, the better my chances are of getting less shuttering and 'clearing'. I may be able to move throttle forward VERY slowly then and I *may* be able to actually get throttle to 3K RPM and mow for a short bit before the RPM's start dropping off again. Engine oil light NEVER comes on and engine remains perfectly cool. I have checked the air filter and oil and they are fine. Hubby did change the oil at 50hrs. and did all of the recommended maintenance. Is this problem due to dirty fuel??? I also tried taking the fuel cap off immediately upon losing RPM's to see if air was needed....no difference. There is no water in the bowl and no obvious debris. If it is dirty fuel, after bleeding the system, it is necessary to replace both primary and secondary filters, right??
This stuff ALWAYS happens when hubby is out of town.
I am chilling the wine. Any and all help is MOST appreciated. I would much rather be riding my horse.

 

[mahlers]

It certainly sounds like a fuel problem. A similar thing happened to me a while back, and it turned out to be a bunch of debris in the fuel tank that was clogging up the fuel inlet. I'm not sure how it got in there because I'm very careful with fuel, and when it happened I only had around 70 hours on the tractor. I drained the tank, blew out all the lines, and everything has been fine since.

 

[newholland4me]

Thank you for your post. Hopefully, we will find out tomorrow if the problem is fuel related. Going to drain all of the fuel, install new filters (have primary & secondary) and replace with new fuel. I sure hope this resolves the problem. I would love to get my front field finished. Do you happen to know of a good additive that will clean and lubricate injectors as well as supplement the low sulphur diesel? Thanks again.

 

[newholland4me]

Mechanic came this morning, bled fuel, replaced both filters, replaced fuel with red diesel. Weather is crumby so no mowing today. Hopefully, I will be able to try tomorrow and HOPEFULLY the problem has been resolved. The mechanic did not see anything significant in the fuel that he drained nor anything in either filter of any significance. So.......???? Guess I will know soon enough.

 

[Soundguy]

Goo dluck with it.

In general.. diesels that starve out and laock power have a fuel issue like you have bene told. Air starvation can do it as well.. but you usually get black smoke when that happens..

I'm not familiar with TZ series.. but ont he larger units, the fuel petcock can become plugged with biologicals and other gunk.. etc..

Soundguy

 

[JC-jetro]

Ok,
This stuff ALWAYS happens when hubby is out of town.
I am chilling the wine. Any and all help is MOST appreciated. I would much rather be riding my horse.

I once had the same issue and it was fuel related. I was scooping up some cow manure and actually got stuck in it I kept going back and forward trying to get out of the muck to no avail.. ended up putting some broken branches below tires just to get some traction. I finally got myself out of sticky situation. I had enough and was heading to the barn and the tractor started shuttering , could not raise the rpm, and ran pretty rough but never died. At the the barn I took the fuel hose off and tried to open the fuel valve and it only trickled . I then pushed a bit of compressed air in to the open valve and actually helped the situation but still not a steady stream. I ended up taking the tank off, dumped the fuel in the container and cleaned the valve port and the tank. Although I had no rust and just a bit of sand in the bottom of the tank what caused the blockage was very small thin shaving of the rubber seal from my tank fuel cap. When I looked the bottom of the cap I notice a bit of loose rubber hanging.. I guess the shaving went in the tank when I tightened the cap and all the back and forth I was doing sloshed the fuel around and caused the rubber shaving block the valve. I made sure my tank was completely clean before I put the old fuel back in the tank using a big funnel and a through couple of clean coffee filters.

Jc,

 

[newholland4me]

Well, I just mowed for a short while (in the snow!)...just big light flakes falling here in Fort Worth. I mowed for about 30 min. and the SAME thing happened again!!! I was making a hard right turn (if that is significant??) and RPM's started dropping off, engine shuttering and I had to shut it off. I wait maybe 3 min., started engine and had to keep it at around 1K RPM for a few min and then slowly increase RPM's to around 2K and took her back under carport and parked. I am so frustrated. This 'stuff' always happens when I am flying solo. Any more suggestions out there??
Oh thought I would add: never any black smoke, but mechanic did say that he read on the NH tech. support something about gas cap not allowing air. So when this has happened, I have loosened the gas cap immediately, but to no avail.

 

[dqdave1]

It is a fuel problem. Remove fuel line before filter and check fuel flow; this will determine if you have a fuel plug in tank. If good flow; remove fuel line at where it enters the injector pump, you should have good flow there. I am assuming it is gravity feed. If you have flow there; I would bleed the injector pump while engine is off, to remove all air. Try it again. You may need to bleed each injector ( high pressure; be very careful) to rid of air but if it runs fine for the indicated time I do not think that is your problem. You may be sucking air into fuel lines at fuel filters; make sure they are tight.

 

[WTA]

I was going to suggest maybe you got some gasoline in the fuel but you already solved that problem. I've had to fix a bunch of them like that that ran exactly as you described. You already had the fuel changed out though.

My gas cap is vented, Yours may be too. Try loosening the cap next time it does it and see what happens. I also have a vent between the two sides of the gas tank and another one going from the top of the tank up into the top of the fender. Mud dobbers are notorious for getting into things like that if the cap falls off the line.

I would recommend pulling the fuel lines like was already suggested too and see if you have a strong flow through all of them. It almost has to be one of the lines or a vent plugged somewhere.

 

[wny770]

Take this for what it's worth.... My little TZ25 was starting to run rough, loose RPM's at times. A friend of mine told me to use power service. Yeah, OK... So I tried it and WOW. All the rough running went away. Now, I make sure and put a very little amount in every new tank. Maybe I had some dirt? water? I don't know, but it made a beliver out of me.

 

[newholland4me]

Thank you for all of your posts. I am printing them out and will see what/where we go from here. I have to say that I was not that impressed with the mechanic NH dealership sent out. We chatted and his experience with NH is one year and he has NEVER worked on a TZ previously. Don't know if that is necessarily significant? I am going to contact the dealership where we purchased the tractor as I feel much more confident with them. The only problem with that is it is quite a distance away. I do have a vented gas cap and I did try immediately loosening to no avail. Even thought I 'might' attempt to cover the tank with a piece of old nylon stocking to keep debris out and then see what happens. I have purchased Lucas fuel treatment, but have not yet put any in. Thought I would try and operate without adding first and see what happened post new fuel and new filters. I agree with most of you that it is a 'fuel' problem of some sort, but hey, what do I know?? I am so frustrated at this point, but may continue to limp along at least to finish up the front field. (have VERY little left) and then park the tractor until my husband gets back on the 28th. Just drives me crazy because I can't figure it out....obsessive compulsive disorder kicking in. *sigh* And, then to add the frustration, we just purchased this tractor brand new April THIS year.

 

[newholland4me]

Forgot to add: Please keep the suggestions coming. Can't hurt. Thank you!!

 

[dqdave1]

I would think it is under warranty.

 

[jinman]

Forgot to add: Please keep the suggestions coming. Can't hurt. Thank you!!

I didn't want to enter this thread with my opinion since everyone is saying exactly what I would have said. Being the curious type I am, I could not resist looking at your fuel system diagram on the New Holland website. Click on "Parts Search," enter your model, TZ25DA, and then look at "Engine Equpment", "Fuel Tank & Related Parts" for your diagram. I'd give you a direct link, but the site won't let me do that.

NH Parts Search

Here is the first bad news. This is one of the most complex fuel feed systems I have ever seen. Your system has two fuel filters a fuel pump, and a reserve fuel system. Not having an operator's manual, I don't know how the reserve fuel system works, but maybe if you turned it on, it would supply fuel well enough for you to finish mowing...that is, if you want to go out in this rainy weather we are having in the Fort Worth area. Perhaps there is a switch that turns on the fuel pump for the reserve system. Maybe some other TZ25DA owner will see this and give a more definitive answer.

Finally, part number 50 on the diagram is a hose. There is a note that says it has been shortened to improve flow. That tells me that you are not the only one with fuel flow problems. This has been a problem and New Holland shortened the hose to increase flow. The young mechanic they sent out probably didn't have a clue about this. Also, you may find the dealer doesn't even know.

For whatever reason you are having fuel flow problems, it is surely not your fault or anything you are doing wrong. It could be debris in the lines or just cooler weather causing the fuel to flow a little more slowly. In general, I'd say in the North Texas area, we don't have many problems with trash or water in our diesel. After many years of running diesel vehicles and tractors, I have never had a contamination problem. Of course, yours could be something left in the tank during manufacture and now it is just showing up.

So I think you might look for how the reserve system is enabled and plan on having your dealer check your system for the most up-to-date changes. Since you are in warranty, they should help you find this problem with more than a greenhorn mechanic. You need expert help.

I'm attaching a diagram from the website.

 

[newholland4me]

First of all, thank you for taking the time to research and post. I will definitely check out the NH site and find the info. per your instructions and then print for my husband once he returns from India. I have definitely decided NOT to try and mow in this weather....uh, mowing when it was snowing was my limit. My husband is with you regarding contaminated fuel (not), but everyone had me convinced so had to give it a try. I will now await his return and let him decide how he wants to proceed. But, your information certainly holds merit and yes, you are correct........don't assume that the dealership knows either. Fortunately, my husband is very mechanically inclined so your information from NH site will garner much interest.
Hey, I am grateful that you are curious. I appreciate your input and my logic tells me that you are probably on to something.
Have a good weekend in spite of the weather.
Thank you again.
Karen

 

[kcharbon]

Jim - the reserve tank is a small tank that sits inline between the main fuel tank and the first fuel filter. It looks like it holds about a pint (a little larger than a typical juice box). Hose #13 comes out of the bottom of the fuel tank and goes into a port on the reserve. Hose #15 comes out of the reserve and attaches to the first fuel filter (#27). From there it travels under the operator platform and up to an electric fuel pump somewhere under the dash panel. From there it goes to the filter/separator, then the injector pump.

Karen - have you noticed if the fuel pump is running? It'll make a clicking noise from under the dash. You probably won't hear it with the engine running, however. Maybe a loose electrical connection to the pump is the cause?


(There - after a year of lurking and learning I finally get to contribute something! )

~Kevin

 

[newholland4me]

Hi Kevin,

No I have not noticed...uh, probably because I don't know exactly what to listen for. I am pretty sure that the mechanic said that the fuel pump was running, but not positive. Sounds like you really know this tractor. Do you happen to live in Fort Worth?? Just kidding. I am printing out your post and passing along to my husband. (home on Wed.) Right now, the weather is not cooperating at all so I have not had a chance to do anymore 'experimenting'. I am so glad that my dilemma has given you an opportunity to contribute and I am hoping that your information will also contribute to a solution. I love 'ole Bessie', but she is really becoming a source of frustration here lately. And, forgot to add previously, yes the tractor is still under warranty. *whew* Keep the suggestions and information coming. Thanks again!!!

 

[newholland4me]

Hi Jinman,

I just went to NH and found that 'note' regarding fuel hose length. You are a remarkable 'sleuth'. I sure hope that this is the problem. Sure would save a lot of time and headaches. Looks a little suspicious too, huh?? Now, when I looked at the engine schematic, holy tamale!! I think my eyes just crossed and rolled back into my head! I have NO idea what I am viewing. I am SO way over my head here. I have bookmarked the page and will certainly be sharing with NH dealership/svc. as well as husband. Thank you for all of your efforts and expertise.

 

[jinman]

Hi Jinman,

I just went to NH and found that 'note' regarding fuel hose length.

If you've made it this far, you've got a good understanding of what I meant by a complicated fuel system. I suspect you will find the problem is something simple. It might even be that additional filter that is separate from the main filter bowl. The fact that the engine runs fine without a load and then sputters when you put it under load is a sure sign of fuel starvation. You just have to find and eliminate the source of the obstruction.

May I ask what part of India your husband is in? My company has just acquired a company in Bangalore. Last week we were video-conferencing with our colleagues there and I would not be surprised to have to make a trip or two there within the next couple of years. However, most of our work can be done by teleconference or web meetings. They are a lot cheaper than travel and hotels.

 

[kcharbon]

The fuel pump makes a clicking or rattling sound from under the dash (near the ignition switch). You should be able to hear it when you turn the key from off to run or heat. Mine makes a pretty noticable noise while waiting for the glow plug cycle to time out (I'm in Vermont - starting to get chilly out).

I did check mine, and I have the long version of hose #50 ... I can see why they shortened it. It runs from the filter on the engine into a tee, then one of the lines from the tee goes back to the fuel tank (overflow), and the other side of the tee goes up to the base of the injectors, flows through each injector, then to the input of the injector pump (fuel preheat?). There is also another hose directly from the filter to the injection pump. I can see why they shortened the hose - on my TZ it forms a 'U' shape ... it probably got kinked on some tractors. I'll try to post a picture tomorrow of how mine is.

~Kevin