TC-35D Fuel Problem

[highway32south]

My NH TC-35D started hesitating, then just died. Suspecting a fuel issue, I emptied the fuel filter bowl and cleaned the filter. There was some sludge in there. I replaced the filter and bowl, made sure to allow fuel to rise all the way to the top before tightening down the bowl, then commenced to loosen the lines at the fuel injector pump. Turned over the engine...nothing. By removing and replacing fuel lines, I traced the problem back to the fuel pump...fuel goes in, nothing comes out, even when cranking.

Now this is when I (a VERY novice mechanical guy) started doing some research just to be sure I wasn't ordering parts I didn't need. I found mention of a "fuel pump relay." Now the picture I've hopefully attached correctly shows the fuel pump as pictured on Messick's website. I haven't taken mine out of my tractor yet, but this looks pretty much like it.

I see no electrical connection anywhere for a relay to engage or disengage the pump. I know there's a solenoid on the fuel INJECTOR pump, which definitely would have a relay or fuse, but not just the fuel pump. So, finally......the questions:

1. Am I right in assuming that this fuel pump is mechanically operated and that there's no "relay?"

2. Do these things go bad often? Would water or sludge screw them up to the point to where they need replacing?

3. Is there a way to clean/flush/repair these things?

4. Does anyone agree that the pump is most likely the culprit?

5. Last but not least...can I, the aforementioned non-mechanically inclined guy, replace this thing without totally screwing up my tractor?

'preciate any help I can get!

 

[thepumpguysc]

You can SEE it comes apart.. 1st section has a CLEANABLE filter screen, under that are the valves and under that is the diaphragm..
Just remove the lines from the lift pump and get someone to spin the engine.. you can see or feel it, sucking & blowing.. good luck.
OH.. take a scribe/a pick or a screwdriver & mark the pieces as to where they are ORIGINALY..

 

[highway32south]

Awesome! I'll try that when I get home from work! Thanks.

 

[Jerry/MT]

My NH TC-35D started hesitating, then just died. Suspecting a fuel issue, I emptied the fuel filter bowl and cleaned the filter. There was some sludge in there. I replaced the filter and bowl, made sure to allow fuel to rise all the way to the top before tightening down the bowl, then commenced to loosen the lines at the fuel injector pump. Turned over the engine...nothing. By removing and replacing fuel lines, I traced the problem back to the fuel pump...fuel goes in, nothing comes out, even when cranking.

Now this is when I (a VERY novice mechanical guy) started doing some research just to be sure I wasn't ordering parts I didn't need. I found mention of a "fuel pump relay." Now the picture I've hopefully attached correctly shows the fuel pump as pictured on Messick's website. I haven't taken mine out of my tractor yet, but this looks pretty much like it. View attachment 511717

I see no electrical connection anywhere for a relay to engage or disengage the pump. I know there's a solenoid on the fuel INJECTOR pump, which definitely would have a relay or fuse, but not just the fuel pump. So, finally......the questions:

1. Am I right in assuming that this fuel pump is mechanically operated and that there's no "relay?"

2. Do these things go bad often? Would water or sludge screw them up to the point to where they need replacing?

3. Is there a way to clean/flush/repair these things?

4. Does anyone agree that the pump is most likely the culprit?

5. Last but not least...can I, the aforementioned non-mechanically inclined guy, replace this thing without totally screwing up my tractor?

'preciate any help I can get!

Since diesel engines are shut down by cutting off the fuel, the relay you speak of must be for the fuel cutoff solenoid. You are correct that the rest of the pump is a hydromechanical device and the solenoid opens to deliver fuel either via gravity or via a mechanical lift pump to the injector pump. Some pumps are totally mechanical with the fuel cut off occurring via a mechanical lever that stop cocks the fuel into the pump when a control cable is pulled

Any mechanical device can go bad and an injector pump is no exception. Many times however, the fuel delivery to the pump is the culprit not the injector pump. People forget to turn on the fuel valve at the tank (Yes, it happens!) Tank outlet strainers become clogged, the screen on a lift pump can clog, the lift pump can fail, the fuel line can get pinched, the filter head clogged, the o-rings on some filters get installed improperly, solenoid shutoffs fail closed, the filter clogs. Keeping the fuel clean and water free is the secret to long injector pump life and I think the pumpguysc would agree with me on that.

Personally I would never attempt to "clean a filter" ( I would clean a screen, but not a filter). I don't think that is really possible. Did you bleed the system at the connections to the injector before you cranked the engine.

Finally, no, I don't think the pump is necessarily the problem. You have to eliminate all the other sources of low fuel delivery. When you have full flow delivered to the injector pump and have properly bled the system and it still won't run properly then and only then would I suspect the injector pump.

 

[highway32south]

Since diesel engines are shut down by cutting off the fuel, the relay you speak of must be for the fuel cutoff solenoid. You are correct that the rest of the pump is a hydromechanical device and the solenoid opens to deliver fuel either via gravity or via a mechanical lift pump to the injector pump. Some pumps are totally mechanical with the fuel cut off occurring via a mechanical lever that stop cocks the fuel into the pump when a control cable is pulled

Any mechanical device can go bad and an injector pump is no exception. Many times however, the fuel delivery to the pump is the culprit not the injector pump. People forget to turn on the fuel valve at the tank (Yes, it happens!) Tank outlet strainers become clogged, the screen on a lift pump can clog, the lift pump can fail, the fuel line can get pinched, the filter head clogged, the o-rings on some filters get installed improperly, solenoid shutoffs fail closed, the filter clogs. Keeping the fuel clean and water free is the secret to long injector pump life and I think the pumpguysc would agree with me on that.

Personally I would never attempt to "clean a filter" ( I would clean a screen, but not a filter). I don't think that is really possible. Did you bleed the system at the connections to the injector before you cranked the engine.

Finally, no, I don't think the pump is necessarily the problem. You have to eliminate all the other sources of low fuel delivery. When you have full flow delivered to the injector pump and have properly bled the system and it still won't run properly then and only then would I suspect the injector pump.

Excellent input...thanks! Here's what I did:

As suggested by the pump guy, I unhooked the fuel lines going into and out of the fuel pump. I removed the screws from the top of the fuel pump and removed the cover. The flimsy membrane-like material that I assume is the filter had some "gunk" on one side of it. I scraped that off with my finger and wiped everything off the top of it the same way. Looking back, I wish I had used some carb cleaner on it.

I re-assembled the pump, and turned over the engine. There was definitely adequate fuel flow to the pump, but still nothing came out until I lifted the fuel line going into the pump to where gravity might give it a helping hand. Then I had some flow, but it was very slow. It stopped flowing when I stopped cranking the engine, so I feel safe in assuming that my "gravity assist" wasn't the only reason I had flow.

That was about the time I decided to say the heck with it and order a new fuel pump from Messicks. It'll be here Monday. I'll definitely let y'all know what happens......

 

[Jerry/MT]

Excellent input...thanks! Here's what I did:

As suggested by the pump guy, I unhooked the fuel lines going into and out of the fuel pump. I removed the screws from the top of the fuel pump and removed the cover. The flimsy membrane-like material that I assume is the filter had some "gunk" on one side of it. I scraped that off with my finger and wiped everything off the top of it the same way. Looking back, I wish I had used some carb cleaner on it.

I re-assembled the pump, and turned over the engine. There was definitely adequate fuel flow to the pump, but still nothing came out until I lifted the fuel line going into the pump to where gravity might give it a helping hand. Then I had some flow, but it was very slow. It stopped flowing when I stopped cranking the engine, so I feel safe in assuming that my "gravity assist" wasn't the only reason I had flow.

That was about the time I decided to say the heck with it and order a new fuel pump from Messicks. It'll be here Monday. I'll definitely let y'all know what happens......

So the pump you are talking about is the lift pump, not the injector pump. I guess I was confused about which pump you were talking about.

If you put a "T" in the line at the outlet from the lift pump, it should put out 2-5 psi. You need a low pressure gauge to measure that with some degree of accuracy.

 

[highway32south]

Well here I am with another fuel problem. My tractor is running on only two of three cylinders. I verified that by unscrewing the lines one-by-one to each of the three fuel injectors. There was no change in the way it was running when I unscrewed the line from the left-most injector (as you're looking at the engine block), but when I re-attached the line and unscrewed the line from either of the other two injectors, the engine cut out.

I disconnected all three lines from the fuel pump and had fuel running from all three ports of the fuel pump, although the rate of fuel flow from the port that went to that left-most injector was not quite as much as the other two. Figuring I was just seeing things, I discounted that and ordered a new fuel injector. Replacing the fuel injector yielded no change.

So here I am thinking it must be the rate of flow from that one port of the fuel pump that is causing me problems. The (additional, believe it or not) problem is that the fuel pump comes as a whole assembly, and I cannot order the individual...whatever they're called. The IPB on Messicks shows the parts that comprise the fuel pump, but most of them cannot be ordered.

So...any advice? I don't want to pay well over a thousand dollars for a new (remanufactured) fuel pump, especially if I'm wrong! Thanks, all......

 

[Jerry/MT]

Well here I am with another fuel problem. My tractor is running on only two of three cylinders. I verified that by unscrewing the lines one-by-one to each of the three fuel injectors. There was no change in the way it was running when I unscrewed the line from the left-most injector (as you're looking at the engine block), but when I re-attached the line and unscrewed the line from either of the other two injectors, the engine cut out.

I disconnected all three lines from the fuel pump and had fuel running from all three ports of the fuel pump, although the rate of fuel flow from the port that went to that left-most injector was not quite as much as the other two. Figuring I was just seeing things, I discounted that and ordered a new fuel injector. Replacing the fuel injector yielded no change.

So here I am thinking it must be the rate of flow from that one port of the fuel pump that is causing me problems. The (additional, believe it or not) problem is that the fuel pump comes as a whole assembly, and I cannot order the individual...whatever they're called. The IPB on Messicks shows the parts that comprise the fuel pump, but most of them cannot be ordered.View attachment 556688

So...any advice? I don't want to pay well over a thousand dollars for a new (remanufactured) fuel pump, especially if I'm wrong! Thanks, all......

If your engine is not firing on one cylinder it may or may not be fuel related. It could be due to low compression caused by a broken valve spring, a burned valve, a badly adjusted valve, or a burned piston from a leaking injector, worn or broken rings, etc. Did this just happen suddenly while you were working the tractor?

(" I disconnected all three lines from the fuel pump and had fuel running from all three ports of the fuel pump, although the rate of fuel flow from the port that went to that left-most injector was not quite as much as the other two." Figuring I was just seeing things, I discounted that and ordered a new fuel injector".)

If in fact the flow from the fuel to the bad cylinder was low from the injector pump discharge, how would an injector change help that? You might try disconnecting each line at the injector, one at a time, cranking the engine for thirty seconds and catching the pump output in a measuring cup. Record the measured fuel delivery for that 30 seconds and repeat this for each cylinder and see what the flow is for each cylinder. If you have a significant difference between the measured flow rate between the cylinders, then the pump might have a problem. The cylinder should still fire but will not produce as much peak pressure in the cylinder and the engine power out put will be down.

If I am understanding your problem description and what you did for diagnosis, I'd be doing a compression check on the engine.

 

[RickB]

Vote #2 for a compression test.

 

[thepumpguysc]

The individual parts for the injection pump CAN BE ordered.. but I'm tellin you, you don't wanna mess w/ it..
Just because you have a "break-down" doesn't mean you know how it comes apart..
There IS a method to this madness..
AND the break-down doesn't show ALL the parts inside the pump.. & they are critical to its operation..
If you would like to send me an email, feel free.. THATS WHAT I DO.. rebuild injection pumps.. TPG