FDJ81 Leaking Injection Pump Voodoo (3 Viewers)

[marcjs]

My '91 JDM HDJ81 recently developed a drip from the injector pump, which seems to cure itself once warmed up.

I was planning to investigate the source, and temporarily reseal if appropriate, but then after a visit to the local Sam's Club I cut the ignition and she kept on running at very low RPM...just stumbling over and over.

I attempted to restart, but she just kept stumbling along. Killed ignition, and she eventually stopped after a minute or so. Freaked me out biggly because I was fearing a runaway from a blown turbo seal or something.

Since it was New Years eve I knew calling AAA for a tow would take foreever. Instead I opened up the air cleaner and got myself a rag in case I needed to snuff her and refired after a short rest. No issue. She ran fine and got me home. No issues with boost, smoke, or anything.

What do the diesel czars reckon happened there? I will add that I then drove it on another occasion and something similar happened, except that time she stopped normally, but upon refiring did the stumbling thing. I noticed there was quite a bit of clicking/clacking occurring within the injection pump. After a short rest, she fired and ran just fine.

Any insight would be appreciated. The rig is laid-up while I await a VE reseal kit to arrive.

Thanks!

 

[Eurasiaoverland]

The only thing that stops these engines is a solenoid valve on the back of the pump which allows fuel to pass when energised, but snaos shut when battery voltage is removed.

If debris was physically stopping the solenoid plunger from closing, that would cause it to keep running. There is a mesh strainer under the solenoid to catch stuff.

The solenoid comes out with either a 24 or 27 mm socket (can't remember which), so should be easy to check.

If there is debris in the pump, then I would immediately take it for a rebuild and make sure the problem which caused the debris is identified and fixed.

 

[marcjs]

@Eurasiaoverland, thanks for your reply. Yes, I understand the operation of the cut-off solenoid and that it should effectively stop the running once 12v is removed via shutting off ignition switch.

I was questioning whether I could have had an alternate supply of combustible fuel entering thru the crossover pipe, which in theory is possible if my turbo seal was leaking. I pulled the pipe today and to my relief discovered it to be oil-free. That leaves only the possibility of debris hanging the solenoid. Prior to pursuing that issue, I wanted to first identify the source of the leak.

I cleaned the pump with brake cleaner, fired her, and observed the appearance of diesel, whick looks to originate from between the housing and distributor block. Bummer, as that goes beyond a simple in-situ fix likecI remedied a few years ago when the seal on the top cover went.

Access to the distributor block seal requires pump removal, and setting it on its nose to split the distributor while keeping the plunger and springs from falling out. Therefore, at this stage I will seek professional assistance.

Can anyone recommended a stateside diesel shop with experience woth Denso VE pumps? It'd be ideal if someone in the Charlotte NC area would fit the bill .

Thx, Marcel

 

[roma042987]

I have a cherry of a diesel injection shop down the street from me. Tell him the guy with the diesel cruisers sent you.

 

[donnerpassing]

@Eurasiaoverland, thanks for your reply. Yes, I understand the operation of the cut-off solenoid and that it should effectively stop the running once 12v is removed via shutting off ignition switch.

I was questioning whether I could have had an alternate supply of combustible fuel entering thru the crossover pipe, which in theory is possible if my turbo seal was leaking. I pulled the pipe today and to my relief discovered it to be oil-free. That leaves only the possibility of debris hanging the solenoid. Prior to pursuing that issue, I wanted to first identify the spurce of the leak.

I cleaned the pump with brake cleaner, fired her, and observed the appearance of diesel, whick looks to originate from between the housing and distributor block. Bummer, as that goes beyond a simple in-situ fix likecI remedied a few years ago when the seal on the top cover went.

Access to the distributor block seal requires pump removal, and setting it on its nose to split the distributor while keeping the plunger and springs from falling out. Therefore, at this stage I will seek professional assistance.

Can anyone recommended a stateside diesel shop with experience woth Denso VE pumps? It'd be ideal if someone in the Charlotte NC area would fit the bill .

Thx, Marcel

There is a video on YouTube from a good long while ago on a Bosch VE pump distributor head o-ring replacement that I’m going to attach the link to here. The Bosch VE pumps are effectively the same in 4 cylinder and 6 cylinder versions from the boost compensator housing down.

In the video they “load up” the pump on the cam inside, which keeps all the internals/shims snug and in place so you can back the distributor head enough to replace the o-ring. You go bolt by bolt(the 4 holding the distributor head down) until the o-ring is in place. Then just tighten them up again.

This repair also lead me to more searches and I came across the DIESEL GEEK kit, which is a Viton seal O-ring kit that is the exact same size as the one on our diesels(mines a 1hdt). It comes with incredibly good instructions to do the repair which is essentially the same as the video/on our pumps as well. I have the exact same leak on my pump and have the kit/research ready to go, I’m just waiting to do it when I tear it down for an intercooler install as well as other goodies this winter.



I’m having a hard time justifying a full blown pump rebuild/install at only 125k kilometers, especially if I can do something about it myself. If for some reason it doesn’t go as planned, the pump will be coming off for a rebuild as the other seals probably aren’t far behind

 

[donnerpassing]

https://cdn.shopify.com/s/files/1/2597/0906/files/TDI_Injection_Pump_Head_Seal_Replacement.pdf?15651934029198646224

Diesel Geek Instructions that are pretty darn good. If anyone else has successfully done this repair, I’d be stoked to hear how it went. If not, then I’ll report back when I attempt it in the next month or two

 

[marcjs]

@donnerpassing, that's fascinating!

Unfortunately the 1HD-T (and I presume FTE) pumps are packaged much closer to the block than the Cummins, which would make that surgical operation that much more of a challenge.

Additionally, our top plate (governor cover) features a speed control spring and seat that need careful removal (drop any part and you'll be pulling the entire pump to fish out), but that's trivial compared to ensuring the plunger shim doesn't drop out.

All-in-all it looks doable, but I'm not sure I'd be content only addressing the immediate issue...what's to say another seal/o-ring doesnt fail in six months??? My rig is a'91 with 340k km on it, so I feel compelled to replace all rubber parts while inside. I'm definitely interested in the Viton ring, however, as my reseal kit from Spaco Diesel (Italy) contained only standard butyl rubber parts.

Perhaps I'll change my mind if I find removing the pump a PITA. Nonetheless, I'll keep you posted as I get through my process and would appreciate if you'd do the same!

Thx, Marcel

 

[donnerpassing]

@donnerpassing, that's fascinating!

Unfortunately the 1HD-T (and I presume FTE) pumps are packaged much closer to the block than the Cummins, which would make that surgical operation that much more of a challenge.

Additionally, our top plate (governor cover) features a speed control spring and seat that need careful removal (drop any part and you'll be pulling the entire pump to fish out), but that's trivial compared to ensuring the plunger shim doesn't drop out.

All-in-all it looks doable, but I'm not sure I'd be content only addressing the immediate issue...what's to say another seal/o-ring doesnt fail in six months??? My rig is a'91 with 340k km on it, so I feel compelled to replace all rubber parts while inside. I'm definitely interested in the Viton ring, however, as my reseal kit from Spaco Diesel (Italy) contained only standard butyl rubber parts.

Perhaps I'll change my mind if I find removing the pump a PITA. Nonetheless, I'll keep you posted as I get through my process and would appreciate if you'd do the same!

Thx, Marcel

Sounds like a plan to me!

To my knowledge you do not have to remove the top cover(even for us hdt folks), but it does help so that you can visually confirm that the plunger is at its furthest extent and fully loaded up. You can do the same by putting a bolt or wood toothpick in the timing hole in the center of the distributor head and confirm that way as well. I wish there was a complete viton kit, and you could likely match each seal by cross referencing it, and the diesel geek folks could probably look into it, they’re super knowledgeable.

I’m having a hard time accepting the realities of a pump rebuild as well, it’s a pay to play world, and it’s brutal, but worth it for a diesel 80 series

 

[Eurasiaoverland]

I would be more concerned with the rough running after shutdown and noises from the pump than the leak. If there is debris in the solenoid strainer then it has most likely been through the pump internals (vane pump, roller ring and cam plate); the strainer just stops it going into the distributive head.

These pumps are fairly easy to re-seal at home, but you need a few special tools to fully dismantle the pump and reinstall it with the correct timing (plunger stroke). I would not waste time trying to change one seal in situ (which might not even be the source of the leak(s)). What you miss on doing a home job are the dynamic settings (fuel delivery volumes, rate of injection advance etc) which require a proper diesel lab.

Given the symptoms I think the investment in a professional rebuild would be wise, though I would definitely check the solenoid strainer for debris. The ACSD (cold timing advance module) is a culprit for creating metallic wear particles in the pump from where the actuator cam acts on the roller ring.

 

[marcjs]

So I decided to attempt the in-situ head seal replacement last weekend...essentually getting the majority of the prep work accomplished. The pump lid has been removed, the tank drained using a MityVac MV8000 siphon-pump, the injector lines disconnected, and open ports capped.

I have both Star Diesel as well as Spaco Diesel Denso rebuild kits, but I am determined to fit a Viton (FKM, fluoroelastomer) as opposed to NBR (Nitrile Butabiene Rubber, or Buna) one. Neither of those kits state what materials are used in the individual seals.

Star Diesel sells a VE/Zexel head seal separately (part number 31043), which IS FKM, so I purchased a pack of 25. If anyone requires one, let me know and I will happily sell for $5.

The work week is upon us, so it is unlikely I will provide an update before the weekend.

 

[marcjs]

BTW, I have a theory for the run-on I've been experiencing after shutting the ignition switch "off".

Since the seal between the main housing/pump tank leaks enough to form a visable stream to ground, what is to stop the escaping fuel from being injested into the individual ports of the head under the suction of a cylinder's intake stroke?

It wouldn't take much to achieve a combustible mixture (albeit very lean). That scenario could occur even with a functional solenoid shutting the designed supply circuit - residual fuel in the gap, as well as any additional flow-paths created by the lack of a proper seal to the head.

That's my theory, anyway
{Regardless, I'll be inspecting the filter screen and replacing the solenoid during this service}

 

[Eurasiaoverland]

BTW, I have a theory for the run-on I've been experiencing after shutting the ignition switch "off".

Since the seal between the main housing/pump tank leaks enough to form a visable stream to ground, what is to stop the escaping fuel from being injested into the individual ports of the head under the suction of a cylinder's intake stroke?

It wouldn't take much to achieve a combustible mixture (albeit very lean). That scenario could occur even with a functional solenoid shutting the designed supply circuit - residual fuel in the gap, as well as any additional flow-paths created by the lack of a proper seal to the head.

That's my theory, anyway
{Regardless, I'll be inspecting the filter screen and replacing the solenoid during this service}

No chance at all that the vacuum in the cylinder would be enough to open the injector. It would also mean that it sucked fuel in on every intake stroke regardless of a totally unconnected leak.

Plus a leaking O ring between the pump housing and distributive head has no impact on fuel getting into the delivery valves on the back of the head.

If you read up on diesel engines you will see they are quite different from petrol engines. I get the impression from your post that you are imagining the engine sucking fuel through the ports like a petrol engine. Diesel is injected directly into the cylinder, never into the ports.

 

[marcjs]

@Eurasiaoverland, that makes sense. I don't claim to be a diesel expert, just looking for an explanation for odd behavior.

I'll be pulling the filter out tonight to see whether there is any evidence of contamination, but so far the fuel I pumped from the housing was clean, but then again, there may be sediment.

It may be coincidental that the solenoid just began to hang when the head seal began to leak, but as the cliche goes "coincidence is the word we use when we can't see levers and pulleys".

More to come...

 

[marcjs]

Ok, time for an update.

I cleaned the pump as well as I could within a reasonable effort level, pulled all the injector lines off, removed mounting bracket, and went for it.

I had my wife observe the plunger movement toward the rear of the vehicle under thec action of the cam while I turnred the crank via the pulley bolt.

Once we established it was at maximum "on cam" position, I backed out two socket-head screws fitted on a diagonal in small steps - only to discover the head looses compression in the springs before the O-ring is fully exposed.

I'm reasonably confident the plunger never disengaged from the cam, but it is a nerve-wracking experience to get to that point and check for resistance againt rocking the displaced head, only to realize there isn't any!!!

I wound the screws back in and reran the cam position exercise, only to confirm the lack of preload once O-ring began to appear in the gap

Bottom-line: I believe the Denso 1HD-T pumps carry less spring preload than their Bosch VE counterparts, which makes the in-vehicle replacement unsuitable for our case.

I've begun the process of removing the pump, and will keep you posted.

 

[marcjs]

She's out

 

[marcjs]

Update. She's back on the road and running better than ever

Note to the wise: getting old is not for sissies - nor is pulling and reinstalling a Denso injection pump on a 1HD-T. In order of operation and my subjective assessment of difficulty (1- easiest; 4 - most difficult):

• Disconnecting fuel lines from back of pump (3)
  • Start from the top/outboard (#3) and work inboard, and then zig-zag downward (3->6; 5->2; 1->4).
  • 
  • Release and plug at the engine side and downstream clamps first, as that will give lines ability to move free lines out of the way as you move along in sequence.
• Disconnecting bracket from back of pump (3)
  • Awkward to see/access the three M6 socket-heads as the disconnected lines are still hanging around. Note: I didn't remove the inlet manifold, which would eliminate this problem an allow removal of lines altogether. Just seemed like more work to me and I was eager to get the job done.
  • Note: second time around (I'll get to that later), I didn't bother removing the bracket plate from the pump - just the main bolt to the support off the engine.
• Unseating the pump's tapered shaft from the drive gear (2)
  • I used a harmonic balancer puller I got on loan from Advanced Auto. Unfortunately, the provided yoke bolts and the jacking-bolt length made for a territorial battle with the radiator fan shroud.
• Extracting pump once free (1)
  • Slightly awkward getting the shaft clear of gear housing while battling with dangling chaos of dangling lines. Only marginally worse if mounting bracket is left fastened to pump.
• Cleaning /replacing o-rings/seals on bench (1-2)
  • Mostly easy except for the lid seal which needed modification to fit within groove. Mine was sourced from Star Diesel as a kit, so perhaps a factory Denso would not have this issue.
  • I kept the top-cover off until I replaced the head-seal, but reconnecting the governor spring is a bit fiddly as you will discover the first time you attempt it (wasn't my first rodeo as I replaced cover seal a few years back in-situ).
• Reassembly of distributor head onto main pump body (4+)
  • WTF!!! FSM makes this look like a straightforward operation...couldn't be further from the truth.
  • Pump needs to be stood on its nose. I used a large 3/4" drive socket (2"?) to support the pump. Having the cover and boost compensator off helps to balance it this way. A soft vise would be ideal, but I was doing this on a bench away from my not-quite-clean-room garage.
  • Keeping the small springs and larger spring guides installed while inverting the distributor head and feeding the wobbly plunger is non-optimal as an operation.
  • 
  • Note: while doing this the plunger MUST engage squarely into its micron-tolerance bore while its groove remains engaged with its drive pin, the springs balance on their lower seat plate, and the spill ring remains engages in the ball pin of the governor. It makes juggling knives a relaxing pastime. Keep razor blades and sharp objects away from you during this operation as you may prefer a slow-death due to laceration or impalement of scribe into one's eye than what awaits you.
  • 
  • My solution was the use of tooth floss to hold components within the head while focusing on the dauting tasks of balancing the plunger and seat plate during assembly. Many attempts were required, but eventually I prevailed. Definitely not for the faint-of-heart. I would think a highly guarded pro-tip exists for this operation.
  • 
    
  • Now for my BB King number...the first time through I went through all that, reassembled EVERYTHING back onto the truck, and while attempting to get camshaft sprocket #2 to TDC I encountered resistance before getting there. I was applying torque to the crankshaft bolt using a 3/4" drive ratchet during this process, and despite having passed through a compression stroke never felt such strong resistance. I accepted the fact that OBVIOUSLY SOMETHING WENT WRONG and repeated the whole operation above once again.
  • Having acquired wisdom after my first go-around, I made sure that I was able to put the pump through a full rotation while on the bench and observing the complete rotation and plunger motion from inside. I then reassembled and resumed the timing operation, only to encounter a similar resistance before getting camshaft sprocket #2 to TDC! This time I had confidence to press-through, and sure enough, the resistance was simply the pump compressing the plunger springs.
  • Now all is fine and dandy, except that my tachometer isn't working. Unfortunately, with all the messing around one of the leads broke off flush with the sensor. I have a replacement sensor, but that will be a job for another day!

I am so happy to have my truck running again, and hope this is useful to someone else. in accomplishing the same.

- Marcel