Being a fuel injected system, you should have an electric fuel pump. If the output volume is not sufficent to satisfy the needs of the engine, it could result in symptoms like you have. You could test the output of the pump by pulling the fuel hose loose from the fuel filter outlet and hooking a "test hose" of the same diameter to the outlet nipple of the filter. Next, put the free end of the hose into a clean, clear container (think soft drink bottle) and turn the ignition switch to the RUN position (DO NOT TRY TO START ENGINE). If the fuel pump is performing properly, it should pump about 8 ounces of fuel in about a minute or less. There is also the possibility that the "regulator" the dealer mentioned might indeed be faulty. This "regulator" is a "fuel pressure regulator" Fuel injection systems use a "flow loop" fuel supply. This means that the fuel is constantly flowing from the fuel tank to the injectors (or injector body assembly) and then back to the fuel tank. The fuel pressure regulator is situated in the fuel circuit beyond the last injector to receive fuel. The "fuel pressure regulator" is supposed to allow the fuel pump to build a head of pressure in the fuel injector circuit to a specified value (usually from 36 to 42 PSI) and then the regulator opens to allow excess fuel to return to the fuel tank. If the fuel pressure regulator passes too much fuel back to the tank instead of building the necessary fuel rail pressure.......your engine could show the same symptoms. Do the volume test of the fuel pump before just throwing a new pump at it.

Hey thanks mownie! I'll try the volume test first. That fuel pressure reg., is that the silver looking device just under the air filter housing? It has a line running into the top and one coming off the bottom. The bottom one being the return feed back to the tank?
I truely appreciate the feedback and I'll post back with what I find with the volume test.

Thanks,
Tom

Regulated fuel pressure should be 24-26psi. There is a test procedure in the JD manual. Unregulated (straight from the pump) just needs to be above that, but is normally 60+.

Don't throw parts at this EFI system, as everything is expensive. There are tests for everything in the JD book.

A bad cam gear could also cause this if your engine has the plastic one.

Well, good news is that it wasn't the fuel pump, the cam gear, nor the fuel pressure regulator. Through the process of elimination, using my very limited engine troubleshooting experience, it appears to be the sensor for the manifold air pressure. With the vacuum hose(?) disco'd from that sensor she starts and idles beautifully and I can throttle her up to full speed with no prob. Now the bad news, looked the price up on a JD part site and the blasted thing is $282.00!!!!! Any suggestions on where to look for a cheaper price? Maybe another manufacturer of a similar replacement part. I'm even thinking about pulling the bad one off and try to refurbish it somehow. I probably shouldn't be thinking this but how bad would it be to run it with the vacuum hose disco'd for let's say 12-24 hours of mowing time?
Again, I appreciate in advance any answers or suggestions to my questions!

Tom

Well, i ain't telling ya what to do, but i know what i'd do----

Mmm, it shouldn't run properly without the air pressure sensor disconnected. That basically does what a throttle position sensor does, and varies the amount of fuel injected depending on manifold vacuum. It may idle and rev fine disconnected, but I don't think it will repond to a load properly. I still think something else is up.

You could always plug the sensor hose and try it. Plug it, or the engine will pull dirty air in.

Yea, never thought about how it would respond under load. As far as plugging it, I was considering securing a piece of mesh or gauze over the end of the hose thinking that if I plugged it completely, then it would stall. It really purred when the hose was disco'd from that sensor engine tech, what else are you thinking might be up? Please don't say a compression issue!!!!
I've got some feelers out for a salvaged part and calling some connections to see if I can get the part for less than the $282. I'm going to take the current one off tomorrow after work and see if I can get it apart and maybe hopefully refurbish it myself. I'm no McGyver but I can't see that it would be as complex as repairing say an Ipod.

If this "manifold air pressure sensor" is an "aneroid" type of sensor (uses a diaphragm or membrane to sense change of pressure), it might have a "compensating port" that is open to atmospheric pressure. If so, this port or breather might be clogged with dirt or other obstruction. Also you might want to attach an Ohm meter to the leads or terminals on the sensor and then apply "vacuum" to the hose connection of the sensor (use a "Mitey vac" or your own "vacuum") and observe whether the resistance reading changes at all.

I will check to see if it is clogged and also will check it with an Ohm meter. Thanks again for the info.

I mean you need to plug the rubber hose or dirt will directly enter your engine. Plus that throws off the fuel/air mix.

I know I've unplugged that sensor (the wires) and the engine normally overfuels and dies. It will also blink a code on the dash light. You might want to try and check the input/output of that sensor. I think one wire is 5v +, one is ground, and the other is output. The output should be between 0 and 5v, but usually sensors register something near the middle (2.5v). I suspect you could suck on that tube and see the output change as a type of sensor test. Just brianstorming.

Keep us posted.

No, I'm with ya' engine tech on the dirt issue, I was just thinking of covering the end of that rubber hose with a small piece of gauze to filter out the dirt/dust.

tomc43, forget the Ohm meter check. Now that engine_tech has posted some vitals, I see that an ohm reading may not be meaningful (because the sensor may function like a "variable voltage regulator" instead of a "variable resistor"). The 5 VDC referred to is going to be the "reference voltage" furnished by the ECU. The output signal should vary, up to 5 VDC (as engine_tech stated). The output circuit should return to the ECU. Do like engine_tech suggests and check the output voltage while applying vacuum to the sensor.

I'll check that output voltage. I stopped at the local JD dealer/service center and took that sensor in. Their service guy said that he can't recall the last time that he replaced one but suggested that maybe I have either a ruptured fuel line in the tank or one that has possibly slipped down from the "sending unit". That it would possibly still give me a decent volume of fuel but maybe lacking sufficient pressure. He went on to say that by disconnecting the vacuum line off of the sensor that I'm basically "tricking" the computer into thinking it's at an extreme altitude and therefore triggering a richer mix, possibly overcompensating the ruptured/loose fuel line in tank? Well it made sense they way that he described it, not so sure that I have relayed it clearly here!

What the dealer told you is good advice, and something I wish I had thought of. I've seen the fuel hose between the pump and the sender split causing just that situation. You can remove the rear fenders and then easily access the sender/pump assembly.

Good luck!

tomc43, I hope that the guy at the dealer did not actually say (or even imply) that the ECU (computer) would increase the fuel delivery rate (pulse width) of the fuel injector to compensate for "extreme altitude". The correct "adjustment" for high altitude would be to either "lean out" the fuel a bit, or increase the volume of induction air.

mownie, he was not specific as to if he meant high or low altitude. He was just speaking in general that by disco'ing that vacuum hose that I was tricking the computer into thinking the atmospheric pressure was different that what it actually is here in the flat farmlands of NW Ohio.

The reason those tractors use an air pressure sensor is so they can compensate for different altitudes. JD's first EFI tractor (285) had a throttle position sensor which required a special air presssure sensor option of running at high altitudes so it could adjust the mix. By using air pressure (really intake vacuum) on the 445 the engine automatically compensates. So what the dealer said was a little mixed up, but he was on the right track.

What might be going on is that the engine is overfueling, and when you pull the vacuum hose off that supplies more air which leans the mix closer to correct.

You are doing the right thing by trying to diagnose the system before buying any parts. Never throw parts at those EFI systems, as most of the time it's something simple and not sensor or ECU related.

When you get her all figured out please post the cure. I have a 445, almost 1200hrs without any trouble, but you never know.

Bravo to all that replied with all the great pointers! After seeing all the replies and speaking with the local mechanic I finally found the REAL problem. I put everything back together on the engine except for the vacuum hose to the sensor, fired her up, removed the gas cap and took a listen. Sure enough, I heard some spraying in the tank! Took off the rear body assembly, pulled out the sending/pump unit and found the rupture on the back side of the hose...a nice 3/4" gash. Replaced it with a new piece, put her all back together(including reattaching the vacuum hose to the sensor), reconnected my mowing deck and as I write this, my wife is out mowing the yard!!!
I can't thank you all enough for helping me out in diagnosing the problem!!! Saved me $282 for a problem caused by what probably amounted to a $1.00 worth of rubber...if that! Maybe all said and done an hour of total labor from the time the mower stopped running until now. Great job and what a great website.

Thanks again mownie and engine_tech,

Tom

tomc43, thank YOU for being patient and persistent in your pursuit and prosecution of the problem.

I second that - thank you for your patience. This thread could have easily turned into some giant "I spent $$$$ and can't fix my *&^&% tractor"! Via good diagnostics and process of elimination you found the problem.

I stand by my statement that whenever a 445 doesn't run right it's almost always something simple and "mechanical". It's rarely the EFI system components (ECU, injectors, etc).

Yea, it coulda' been an ugly scene with my financial officer (read wife) had I spent the $282 on a piece that wasn't faulty!phew!LOL! I will be investing in the JD shop manual for the 445 so that the next time maybe I'll be able to figure it out on my own. But I surely do appreciate all of your guys' input and for insisting on not throwing money at the EFI system.
Thanks again,
Tom

Right.........the typical "CFO" finds little humor in that sort of "waste". :^)

I have the same problem with my 445, I have noticed that it hasn't been revving as it did. I hope I can find the problem as easy as tomc43, will be back with my findings. I have two 445 John Deere tractors, the other one is down due to a bad oil leak on the rear of the engine (crank shaft seal) can any of you shed some light on easiest way to change it. I have all the parts.