B1750 will crank but not start…

[Blackberrysquash54]

First off, I’m going crazy with this thing. I’ve got a B1750 with a belly mower. Had it for years. The tractor died while mowing and hasn’t started since. (End of last summer).
1). It turns over strong.
2). It’s got fuel—it DID NOT run out of fuel when it died.
Never the less I did all fuel checks—fuel filter, drained tank and started over with fresh fuel, air bleed. I’ve got good strong fuel flow all the way through.
3). Solenoid functions
4). Fuel shutoff knob is in correct position
The tractor is mostly mechanical with a couple fuses. I replaced those just in case.
It seemingly does everything it is supposed to do. It just won’t fire off.
Any suggestions?

 

[whitetiger]

First off, I’m going crazy with this thing. I’ve got a B1750 with a belly mower. Had it for years. The tractor died while mowing and hasn’t started since. (End of last summer).
1). It turns over strong.
2). It’s got fuel—it DID NOT run out of fuel when it died.
Never the less I did all fuel checks—fuel filter, drained tank and started over with fresh fuel, air bleed. I’ve got good strong fuel flow all the way through.
3). Solenoid functions
4). Fuel shutoff knob is in correct position
The tractor is mostly mechanical with a couple fuses. I replaced those just in case.
It seemingly does everything it is supposed to do. It just won’t fire off.
Any suggestions?

When you bled the fuel system, did you loosen the injection lines a couple of turns at the injectors in the cylinder head?
Does it smoke when cranking? Have you checked your air filter?

 

[Blackberrysquash54]

When you bled the fuel system, did you loosen the injection lines a couple of turns at the injectors in the cylinder head?
Does it smoke when cranking? Have you checked your air filter?

I did loosen the lines and tightened back when air bubbles were gone. Pulled the whole air filter assembly off to gain better access to fuel lines. While I had it off I did blow it out and clean. It wasn’t bad dirty. It does not smoke at all when cranking.

 

[85Hokie]

Just asking - how many hours on this machine, I find it hard to believe - but compression be so low it will not fire? To have that happen in a hot engine would be .......... almost impossible - unless rings quit somehow.

Whitetiger's question about the smoke is an excellent point - if you do not have any indication of combustion ..... we need to look deeper!

I was thinking the fuel mechanical cutoff is "broken" - if that is the case, you would not be getting fuel at all to the injectors.

To cause it to quit while running , and not run out of fuel - something mechanical had to break..... just my 2.5 cents.

 

[Blackberrysquash54]

Just asking - how many hours on this machine, I find it hard to believe - but compression be so low it will not fire? To have that happen in a hot engine would be .......... almost impossible - unless rings quit somehow.

Whitetiger's question about the smoke is an excellent point - if you do not have any indication of combustion ..... we need to look deeper!

I was thinking the fuel mechanical cutoff is "broken" - if that is the case, you would not be getting fuel at all to the injectors.

To cause it to quit while running , and not run out of fuel - something mechanical had to break..... just my 2.5 cents.

It doesn’t have an hour meter but I figure it to be an early 90’s model. I totally agree about with the thought that something mechanical had broken but with full flow coming out of the lines at the top of head I’m totally confused. Do you guys think the clutch safety switch would cause this in some manner? The only known “problem” I know about is that the switch does not have to be depressed to start. But it was doing that before this situation.

 

[Roadworthy]

As far as I know if the tractor "thinks" its safeties have not been satisfied it will not crank at all. If it will turn over without depressing the clutch that indicates the clutch safety switch has failed and the tractor "thinks" the clutch is depressed. Your symptoms sound more like for some reason your injectors are not getting fuel or perhaps your pump is snot providing adequate pressure.

 

[SDT]

It doesn’t have an hour meter but I figure it to be an early 90’s model. I totally agree about with the thought that something mechanical had broken but with full flow coming out of the lines at the top of head I’m totally confused. Do you guys think the clutch safety switch would cause this in some manner? The only known “problem” I know about is that the switch does not have to be depressed to start. But it was doing that before this situation.

I have a B1750 bought new in 93 or 94 and it does have an hour meter in the tach. Believe that all do.

Cannot be the clutch switch. Faulty clutch switch would prevent cranking but does not affect fuel. Since yours cranks without depressing the clutch the switch is out of adjustment but not your no start problem.

A couple of years ago there was a thread herein about a similar B1750 issue. Turned out to be an acorn in the kill knob mechanism preventing the knob from being returned fully to run. Thoroughly inspect the mechanical mechanism and the electrical shut down solenoid for proper operation.

SDT.

 

[Henro]

I have a B1750 bought new in 93 or 94 and it does have an hour meter in the tach. Believe that all do.

Cannot be the clutch switch. Faulty clutch switch would prevent cranking but does not affect fuel. Since yours cranks without depressing the clutch the switch is out of adjustment but not your no start problem.

A couple of years ago there was a thread herein about a similar B1750 issue. Turned out to be an acorn in the kill knob mechanism preventing the knob from being returned fully to run. Thoroughly inspect the mechanical mechanism and the electrical shut down solenoid for proper operation.

SDT.

How easy did it start before the “event” happened?

Sounds like something changed suddenly at the moment the engine quit.

The injector pump is doing something, since you can bleed the lines and fuel comes out (seems so to me anyhow). But whether it is producing sufficient pressure is a question.

I could simulate similar operation on my BX2200 by disabling the fuel cutoff solenoid start coil. Not sure how your fuel is cut off to stop the engine. Perhaps something failed causing fuel to be cut off all the time. But if so, would you still expect to be able to bleed the lines?

Fuel issue, air issue or low compression seem to be three main reasons for non starting of an engine that turns over normally. (Perhaps add glow plugs to the equation, but they would not cause the sudden stop). Apparently you covered the air intake question. Might be time to make some measurements. If I were in your shoes I would think a fuel delivery problem to be likely.

Of course, the reason I never bet is I always lose…