HDJ81 won't idle, stalls at stop signs (1 Viewer)

[splitbuseric]

1991 HDJ81 VX automatic.

Took a trip last weekend with trailer in tow to get a vehicle and on the way home the truck started acting up. First it was a random hesitation on the hwy and then once we got off the highway the truck died at the first stop. managed to get it started by putting the accelerator down and got home by driving two-footed as it wanted to die at low rpms/idle. It seems to go okay at speed though with the odd hesitation.

Removed fuel filter, filled new one with diesel purge, primed and started it back up. Same issues. Added 25L of fresh diesel in case I got bad fuel, no change. After this ACSD began to leak out of shaft seal and I figured it was sucking air there. Removed ACSD and installed block off plate. Truck still runs like s***, same as original problem.

Obviously I am hoping it is just sucking air or something else other than the injection pump is needing a rebuild. This is my daily driver and I need some advice on next steps for diagnosis. If I get it started and set the hand throttle it will idle all day at 1200rpm and above. But not below or when put in to gear. Should I run a fuel hose from IP to a jerry can to try and eliminate air leaks in the rest of the system? Fuel hoses with factory spring clamps at filter housing seem a little loose, perhaps I'll put some gear clamps on there to rule them out....

Suggestions needed as I need to get this back on the road.

 

[yotahed]

I does sound like its getting air into the head. Air in the pump isnt such a big deal since they self purge and bubbles usually go straight to the top of the housing. check/replace the oring at the shutoff solenoid. also check for leakage out the rear plug and the the timing bolt.

 

[BCR4619]

I ran into problem at different points, my fuel line from filter to IP has cracks in the end and when it was cold out it would not start the first few tries so I would assume it was letting air in there... But this was winter

Also my fuel pick-up was clogged and would not idle, I had to keep the idle above 1k and limped it home so I could take the seats out and open the tank.

I think your headed into the right direction by hooking up a jerry can full of diesel to rule out some issues.... Yotahead is also good at troubleshooting with

 

[splitbuseric]

thanks for the suggestions. i forgot to mention that this began when the tank was low on fuel so i should likely look at the fuel pick up. sounds like it can be accessed from the rear interior somehow. i'll check the manual. i will also check those places on the pump yotahead, thanks. so far haven't seen any other fuel leaks.

thanks all.

 

[roscoFJ73]

Does it make a difference when the truck is pointed uphill/downhill ?

Should I run a fuel hose from IP to a jerry can to try and eliminate air leaks in the rest of the system?

I would ,it would isolate the problem between the tank and the pump very quick.

I read somewhere that Denso rotary pumps have one mode for under 1200rpm and another for over. I cant think of the name of the part that controls this.

 

[BCR4619]

@splitbuseric Remove one way bolts on rear (middle row) seats and pull up the carpet and you will see the access door located just before the rear seat foot well.

If you search mud for "HDJ81 fuel filter suction hose" or something like that you will see what I went through.

HTH!

 

[Squash]

Pull the IP
Have the injectors pressure tested
Change the timing belt if it hasn't been done
Clean the small screen mesh filter under fuel shut off soleniod.

A decent shop can do all of this, expect to pay!

 

[splitbuseric]

Update: I got some new fuel hose and ran the IP directly in to a fresh clean jerry can of diesel, eliminating everything between IP and tank. No change is condition/behaviour. I now have the fuel cut off solenoid out and the o ring looks like new, soft and pliable no marks/cracks. I will replace it anyway and look for the screen mesh filter mentioned above and clean it. Barring that I think it is starting to look like a pump rebuild...not sure where to find someone I can trust with that job as I don't think I want to tackle it myself as I've never had one off and the manual doesn't make it look fun.

I need to check the other things Yotahed mentioned above, as soon as I figure out what they are....any other suggestions welcome as well.

 

[BCR4619]

Id trust yotahead with it, I trusted him with my injectors and so far so good... plus he always posts on mud so thats a plus!

If your really in a jamb I have a IP siting here from a running truck that I don't think I need.

 

[splitbuseric]

I am not sure I am confident in removing it; I've done lots of mechanical work but never removed a diesel IP. I say this as he is in BC and I am in ON and that is a bit of a logistical issue.

 

[splitbuseric]

I does sound like its getting air into the head. Air in the pump isnt such a big deal since they self purge and bubbles usually go straight to the top of the housing. check/replace the oring at the shutoff solenoid. also check for leakage out the rear plug and the the timing bolt.

By rear plug do you mean what they call distributive plug in the manual (page FU32 in mine), looks like there is an o ring under there. Can it be removed without issues so I can change the o ring?

Where is the timing bolt you refer to?

 

[Squash]

Did you try a clear hose between filter and IP? Bubbles indicate problems towards tank.
If you can drive these guys can help www.henningersdiesel.com
In Sudbury, Ont. These guys rebuild most IP's for the mining companies.
Shop is clean, testing facilities like pressure and injector spray pattern and parts bring a timing belt and idler pulley change it out you'll be good for another 100,000km.

 

[splitbuseric]

I ran a clear hose directly from IP to jerry can, eliminating filter etc. No bubbles and it still ran poorly.

Thanks for the link. I am not sure whether I'd trust it on a trip to the nickel city, it does run better at speed than idle though. Just who knows for how long....

i am going to put a new o ring on the fuel cut off solenoid tomorrow but the old one looked and felt fine so I am not holding my breath.

 

[roscoFJ73]

I think it will have something to do with the flyweights on the governor or the arm it is connected to. Rather than ask for a rebuild 1st up,get it bench tested and see what that tells them.
The fact it feels like its getting good power at high rpm is good news .
Worn out pumps lose power when they warm up as the precision parts lose their ability to compress fuel.
These sorts of problems require things like new a plunger ,distributor head etc

 

[mudbludger]

I would be jumping at that injector pump on offer from BCR, they are not that big of a deal to remove and fit. You may have to make up a jacking plate to remove it off its taper, easy enough to do. I think i have a drawing around here somewhere for one.

 

[splitbuseric]

Just removed the screen below fuel cut off solenoid for a cleaning. It and the area it sits have lots of chunks of metal. I presume this is very bad....sigh..

 

[BCR4619]

Just removed the screen below fuel cut off solenoid for a cleaning. It and the area it sits have lots of chunks of metal. I presume this is very bad....sigh..

:O

 

[splitbuseric]

I will try to get a pic, I was surprise at how much and the size of a couple of the chunks. Bigger than shavings and one you can make out the shape of whatever has been chopped up.

 

[Squash]

Do a search
A member was successful at back flushing the system
His pics and procedure are there

If this just happened you should have little damage.
I had the same issue but had to drive further...needed one part when rebuilt but could have gone without it if needed.