JCB 217 SIII, can't develop power

[obleck]

Hi All,

An amateur mechanic here.

I picked up this machine at an auction and am just getting into 'er, resolving things one by one.
1998 JCB 217, USA model with "AK" series Perkins 1004-4t (turbo), rated 92hp, (though Perkins says 111hp)
I'm not sure which injector pump (yet).

The machine runs okay under no load, and even with some load, but when I really load it up, say by going up a steep hill or trying to push into a pile of dirt, it won't develop the power, which is to say the engine RPM's aren't coming up with the throttle.

Under it load she does throttle up as expected, though the tach isn't working right (yet).

As best as I can tell by diving into manuals, is that there is no computer or anything regulating the RPM's. All there is, is the governor, the fuel, and the air. I put in new air filters (the old outer filter was pretty clogged). I haven't put in new fuel filter(s) yet, but the machine has the type with a glass cylinder and a drain port, and from the manual it looks like there is also a filter element. I will go through those next. As far as I can tell though, the glass is always full, which tells me the lift pump is working. So I don't know that cleaning it will particularly make a difference. Let's assume not, and that the injector pump is getting all the fuel it wants.

So my question to the gurus out there, is what then?

Again from the manuals, what controls the fuel is a combination of the governor, and it apparently has a turbo boost control which cuts back the fuel at low boost. Just talking through it: I'm guessing the governor works, since I can generate suitable RPM's at low load. However, if the turbo isn't boosting, then the fuel won't come up. I suppose the turbo could be bad, or the boost connection isn't working right (is it a pressure line, or electrical? Couldn't find more info. Unfortunately the machine is out in the field, so I'm back and forth).

Can I disconnect or bypass the boost so the pump will give full fuel?
Is there some way to determine if the turbo is boosting properly?
Could there be an issue with the governor?
Other things to check?

Any advice appreciated.

Thanks!

P.S. as an aside, why does Perkins rate this engine at 111hp, and JCB at 92hp?

 

[Delmer]

Start with fuel, that's the simplest in my mind. The fuel filter bowl is only full because you don't have any air leaks, it won't develop full power without the correct fuel pressure, and that bowl should be under pressure when running in every perkins I've seen. You could tee into the fuel line right before the injection pump, run a hose to a pressure gauge in the cab and see what the fuel pressure does when it bogs down, then you have a logical place to start.

Not knowing the injection pump, and not knowing pumps even if you had the model and serial number, I'd look at the pump. Hopefully just one wire going to the injection pump to shut it on and off, not a harness going to all parts of the engine. You probably have a small diameter line coming from the turbo or intake manifold to the injection pump, that's the boost pressure line. It won't do any good to remove it, but you could tee into that one also and see what the boost pressure does. Not so helpful because we already know that it's not making full power... Plus it won't make power without boost, and it won't make boost without fuel, so what came first???

You could take the intake hose off the turbo and inspect the compressor side of the turbo and get a feel for the bearing wear, wear on the fins, etc.

There is probably not an issue with the governor.

I'd pull the fuel supply apart from the tank to the injection pump, and blow every line and fitting out, then put it back together and see what it does. Or put a pressure gauge in there and see for yourself.

Also, how many hours on it? what kind of shape is it in generally? any chance it's sat for a while without much use?

 

[Junkyard]

It should be similar to my JCB forklift. If it’s got a mechanical lift pump remove the supply line into it, it screws into a large hex flange you can unscrew. It contains a screen which could very well be clogged. I had similar symptoms with mine. If nothing else it’s a periodic maintenance item you can check off the list.

 

[thepumpguysc]

That inj. pump is a DP200 Delphi pump.. its known to blow the diaphragm on the pump..
IF its blown, you wont reach rated rpm's.. They're not easy to change on account of the tamper screws.
1 easy check is> if its blown, it'll be pressurizing the fuel tank{return fuel}.. Run it wide open & loosen the fuel tank cap slowly & listen for any pressure..
I've seen them so blown that it pushes the fuel OUT OF the tank.. {full tank}
If your going to attempt to change the diaphragm{blown} check the screws.. some are 5 sided w/ a nub in the middle & some are 6 sided w/ a nub.
You'll HAVE TO post the pump #'s inorder to get the correct diaphragm kit.{on name plate}

 

[obleck]

Thanks everyone, very helpful suggestions.

I'm going to start with the lift pump screen, and also change any other fuel filters. Based on how clogged the air filter was, I wouldn't be overly surprised if this thing ever had any filters changed (!). Yes, will do oil and hydraulics too while I'm at it.

The Perkins manual for the AK engine didn't mention the Delphi pump, but I'll find out which it is. Thanks for that suggestion. Easy enough to check.

If that still doesn't do it, I'll look into clogged fuel lines and turbo boost control.

A related question: I replaced the air filters, but the air flow restriction light still comes on when I floor it and the RPM's can get up there. Any ideas on that? It could be a simple sensor/pressure sender error, since I do have some electrical problems. e.g. tach isn't working right (reads 500 at idle, then goes down slightly and up to about 500-600 when rev'd)

Thanks again!

 

[Delmer]

Does the manual say anything about the air flow restriction light? How long does the light stay on? like only a couple seconds while the engine speeds up, or does it stay on as long as the engine is at high RPM? or can you have the engine at full speed and then get the light to turn on by putting a load on the engine? I'm trying to figure if there's some logic to what's causing the light to come on, the movement of the engine and wiring harness, or the turbo spooling up and sucking more air. How many wires connected to the alternator, and is the alternator belt tight and pulleys in good condition?

If you couldn't tell, the pumpguy is something of an expert, and since his test is the easiest by far, it would make sense to check that first.

Let us know what you find out.

 

[obleck]

Ah, Delphi=Lucas, company changed names apparently. It is a Lucas 7185/200E.

Delmer, the alternator has two wires running to the tach gauge, as in the wiring diagram (I don't have the exact diagram for this machine, but the wire numbers match all the other versions I have). There is one wire from the "W" terminal which I believe is the unrectified output, and one from a three-connector port which also drives the "engine running" relay. The alternator also has a single heavy gauge wire which is the hot battery bus, and it's grounded through the engine (i.e. no ground wire). There could be some sort of bad ground somewhere, since a lot of other things aren't working right either (e.g. tach, various lights/heater/AC/etc). The air flow light comes on when rev'd up regardless of load. I still need to dive into the electrical. Part of the problem is I don't have a layout of the fuses and relays for this machine, but I think I found one now.

Anyhow, diving deeper, it looks from the schematic like there is only a simple vacuum switch ("Air Filter Vac Switch", #55) that turns on the light. In the air filter section of the manual it talks about this switch being located on the back of the air filter housing. Maybe the switch is compromised and is giving false readings. I'm going to pull all that apart and make sure there isn't some blockage, though the inner filter looked okay. The outer one was completely loaded up. I changed both.

Thanks again.

 

[obleck]

Update:

In short, much improved but still seems a little sluggish.

1) Took the air filters out and looked in there again, and lo and behold, a critter had built a hearty nest up in the air intake, which on my machine is a hose that goes to a screened bulkhead by the front window. There is a small intake on the filter cap, which I think is supposed to have a plug on it but it's missing and I guess the critter found its way in there. Go figure.

2) I took out the lift pump and cleaned the filter screen, which on this one was under the cap. I was expecting it was inline. The screen was coated in fine silt, but didn't seem particularly "clogged".

3) Cleaned the fuel bowl. It had a little scum in the bottom, but not too bad.

4) Put in a new fuel filter.

I forgot to bring some spare fuel, so I pumped the fuel bowl full with the lift pump manual lever, with the fuel filter off. Once it was full, a few hundred pumps later, I put the fuel filter on loosely until it was mostly full and leaking, and tightened it up. When I pumped a bit more, I could hear bubbling in the fuel tank. Is this symptomatic of a bad lift pump?

Once I got her started, needless to say it ran much better with more power, though was still a little sluggish (i.e. power seemed good but is sluggish coming on). The air flow restriction light doesn't some on anymore. I didn't get a chance to troubleshoot the turbo boost though, nor the turbo bypass valve. So those are still unknowns. I think I'll throw a new lift pump on for good measure too.

 

[Delmer]

The bubbling is normal after changing the filter. That wouldn't have anything to do with a lift pump that I can think of. That's what thepumpguy was talking about with the diaphragm leaking, but that's running, and I wouldn't be able to hear bubbling with the engine running under load when you'll get the most boost.

There's plenty of ways to check the fuel return line for air bubbles, and plenty of ways to get those pesky screws off, keep us updated...

 

[thepumpguysc]

Working the HP & hearing bubbles in the fuel tank means ITS WORKING.. what your hearing is fuel being forced thru the pump & back to the tank.. the HP is working.. but just because the HP is.. doesn't mean the actual pump is..
Take off the inlet line AT the inj. pump & spin the engine over.. fuel should SQUIRT OUT & getcha wet..

 

[obleck]

Thanks guys. Pressure test today.

Incidentally, the lift pump on this machine is bolted on with four hex bolts, 10mm socket, so prob an M6-something.

 

[obleck]

Update:

(by the way, this is all very helpful, thanks!)

As noted, it's running better on account of getting more air and cleaner fuel filters, but it's still struggling to develop full power after doing some running today.

I did the test as suggested by thepumpguy: Loosened the fuel intake at the injector pump, fired it up, and rev'd. It did push some fuel out between the threads, though not full on squirting. I suppose I didn't have it particularly loose, but it was several turns from tight. I'm going to drop in a new lift pump anyway, on order, $18.

Next I took a look at the turbo and waste gate. The waste gate lever didn't move regardless of rev'ing. The waste gate actuator hose was pretty cracked on the outside, so I replaced it for now with a 50psi piece of fuel line. Before I attached it to the waste gate actuator, I fired the machine up and basically got no pressure when rev'ing (the waste gate lever was in the open position). From the looks of it, this hose tees off from the turbo output (i.e. intake manifold), and pressurizes the waste gate actuator to open waste gate further. After scratching my head a bit, I did a few power tests with the waste gate open, but no difference. So I'm thinking, is the turbo shot? I figure I should get some decent pressure on that hose. The actuator by the way appears to be functional, as I can pull the rod out somewhat.

Related: there is what appears to be an oil pump forward and below the turbo. There is a large rubber hose (intake?) and a small high pressure hose attached to it. The small hose goes to another small device bolted to the block. It has a metal pipe feeding oil to the turbo, and the high pressure hose feeding it. Pic attached below. The high pressure hose is pretty beat and clearly leaks (I'm going to get another asap). However, is this a further sign that the turbo is shot? One can hear it spool up somewhat, but the whistling is not nearly as prevalent as I would think it should be as compared to other turbo machines I've dealt with.



Assuming the turbo is shot, can I rebuild the turbo, or is it better to just buy a new one? I rebuilt some on an old Ford backhoe I have with a $20 bearing kit and a new impeller, and they work fine. Was pretty simple, though the housings were in decent shape.

Lastly, how does the turbo boost work? It wasn't obvious. I presume there is some sort of pressure hose coming from somewhere to the injector pump, which is a Lucas/Delphi. I imagine if the turbo isn't boosting, then the injector pump is holding back on the fuel and that would be the cause of all this.

It's a theory...

Thanks again.

 

[thepumpguysc]

A turbo is a turbo.. unless its a variable vane turbo.. which I doubt..
a waste gate is there to "bleed off" any excessive pressure the turbo makes.. hence> "waste" gate..
If it not building pressure.. it aint gonna open..
If u feel comfy doing it.. go for it..
Get the #'s off it & search for o/h kits.. break downs.. ect..
You are correct on the theory.. no boost to the engine means no boost to the pump which means the inj. pump wont pump enough fuel..

 

[heymccall]

I dunno your level of diesel experience, but, I can assure you that free revving a turbodiesel will NEVER generate enough boost to actuate a wastegate, ever.

 

[Delmer]

Right, that's the difference between "high idle speed" (which on a diesel is the same thing as "full throttle" ) and FULL LOAD-when the engine is at full speed and the injection pump is pumping as much as it ever will, and the turbo is spinning as fast as it ever will.

The wastegate should be closed except under full load. That "oil pump" is not familiar to me. I doubt it has anything to do with the turbo, where's the medium sized hose go to?

The pumpguy suggested taking the line OFF and cranking the engine with the starter to check fuel flow, he also suggested taking the fuel tank cap off after working it hard to see if a leaking diaphragm is pressuring the tank, that's the test I would do.

 

[heymccall]

And, in addition to my above statement, most diesels will not produce more than, say, 3 psi, if that, when at "high idle". Most are actually under 2 psi.

 

[heymccall]

Myself, I'd be curious to know what color smoke, and how much, is exhausting when at high idle under a two function stall such as boom up and bucket curl?

 

[obleck]

Responses:

heymccall, no smoke under any circumstances, which leads me to believe the injection pump is only operating in non-boost mode.

Good point about the turbo and high speed idle. With full fuel the exhaust pressure will be much higher due to the extra burning fuel, and hence the turbo will be spinning faster. I hadn't considered that. I'll try to see if the wastegate moves under full load.

Delmer, I did those tests. I couldn't take the hose off all the way, because then the engine won't run more than a second or two, but I suppose that's enough. I'll try it. I didn't detect any backpressure coming out of the fuel tank, but I'll try that again too. In any case, I'm just going to put a new lift pump in to eliminate that issue.

I'm not sure what that "oil pump" is, but it's clearly part of the turbo lube system. I couldn't find any details anywhere. The Perkins workshop manual (TPD 1350E Issue 4) is frightfully uninformative. Anyone have something better?

 

[obleck]

I think the Perkins SPI2 is what I need.

 

[thepumpguysc]

There "should be" someplace on the manifold to take "boost pressure".. prob. a 5/16 plug??
A 30psi gauge & a length of hose that'll reach into the cab & your in business.. THEN u can take FULL LOAD boost pres.