1HDT boost compensator adjust, now no throttle response (1 Viewer)

[JSparks]

Hi All.
just tinkering with my new 80 series,
I was trying to reduce the smoke at idle so I took the top off the boost compensator to see where the off boost screw was at on the circular ramp. I also did one full revolution 360. of the diaphragm just to feel the tension and gauge where its at. I did not pull it up more than a mm or 2
I put it all back together and now I have the same idle but absolutely no throttle response, nothing, the truck is idling but moving the throttle does nothing.
please help

it let me back just far enough out of the drive way to be in a really awkward spot.

 

[JSparks]

so got the truck in for the night, pulled the pin to find its been severely messed with.
this isn't the best news but I'm rolling with it.
What is concerning is that from my understanding nothing with the compensator should affect the basic ability of the truck to accelerate.
Could it just be Coincidental timing and is it something deeper in the pump.

 

[troopie]

Did you accidently push off the rod that goes from the accelerator cable to the pump? Don't ask me how i know.... LOL.

 

[cody c]

Did you accidently push off the rod that goes from the accelerator cable to the pump? Don't ask me how i know.... LOL.

Thats what I'm thinking.

I have 6BT with the VE pump, it has a similar boost compensator and fuel pin (I have an aftermarket "denny T" fuel pin" but i did have issues with mine at one point, if it's not working right it will limit fuel and make your cruiser gutless, it will definitely affect acceleration.

The pin you have that was messed with slides against another pin which controls/limits fuel delivery compared to air flow.

 

[JSparks]

thanks guys, my main concern is that when I pulled or twisted the fuel pin could I have dislodged the guide pin? because there was no sign of a guide pin stopping the fuel pin going in again.
following this I undid the 17mm bolt that holds the guide pin, the bolt had a spring behind it but no sign of a guide pin...
worried I need to get it to a diesel mechanic...

 

[JSparks]

all the mechanical linkage is correct afaik, it's a jdm model also if that matters

 

[davegonz]

Can you see the guide pin? I had issues with my 1HZ pump when I turbo'd it and added the boost compensator housing. I had to remove the full load screw and reinstalled the compensator housing. I think the linkage inside was restricted somehow when I first installed the boost comp housing.

 

[Sonofaskipper]

Is it common to find that the pumps on these JDM 81 have been fiddled with by previous owners in Japan?

 

[mudgudgeon]

You should be able to see the guide pin if you look down into the sleeve where the aneroid / boost compensator pin goes.

With the 17mm plug and spring out, you should be able to gently push the guide pin out of the way to reinstall boost compensator pin.

The pin can't fall into the pump, but it could possibly fall out when the 17mm plug was removed (but unlikely).

 

[cody c]

You should be able to see the guide pin if you look down into the sleeve where the aneroid / boost compensator pin goes.

With the 17mm plug and spring out, you should be able to gently push the guide pin out of the way to reinstall boost compensator pin.

The pin can't fall into the pump, but it could possibly fall out when the 17mm plug was removed (but unlikely).

This is what Im thinking, it fell forward into the cavity below where the diaphram sits.

 

[davegonz]

Is there enough room to do that?

 

[mudgudgeon]

Is there enough room to do that?

Nope. Shouldn't be possible. But if the pin has worn away, maybe

 

[JSparks]

Thanks heaps.
My current thinking was along the same lines, I had a really good look in the cavity after removing the boost compensator pin, fished around with tweezers but no luck finding the pin, I am 100% confident it didn't come out when I removed the 17mm nut, not convinced from the photos and diagrams attached that its possible for the pin to fall out.

The other thing I am trying to clarify is according to the LCOOL instructions you can feel the tension change as you rotate the diaphragm and pin assembly, I can still feel this change, is that tension against the guide pin?

Also the boost compensator obviously affects the throttle response and tune however at low RPM there is no boost yet there is still throttle response. Like davegonz said he added a compensator to the 1HZ pump. is my fiddling with the compensator actually the cause of these problems or is it just coincidental that something else in the pump went wrong. I would expect the tune to go to s*** but not to loose any throttle response.

am I missing obvious things like a blocked fuel filter?

 

[JSparks]

the 2nd diagram doesn't clarify but the "lever control spring" and "connecting pin" look like they go in together, but I think the "control lever" actually separates those two parts.

currently looking for a local diesel mechanic but we are still in the middle of summer holidays, businesses are on reduced hours in small town NZ.

to answer someone else question, I don't believe JDM vehicles get messed with any more than normal, however New Zealand gets a lot of JDM imports, and this truck was owned by a mechanic as his shop truck for 12 years with service history, which is why I bought it. starting to realise that it wasn't maintained as well as I thought.

 

[davegonz]

JSparks,
I would remove the boost compensator (easy to do) and see if the pin rattles loose. I would then check the linkage inside and reinstall without the Full Load Screw.

@AlbertoSD has good info and links in his build thread showing how to install the boost compensator. 1985 BJ70 Story and Modifications

 

[mudgudgeon]

the 2nd diagram doesn't clarify but the "lever control spring" and "connecting pin" look like they go in together, but I think the "control lever" actually separates those two parts.

yes, you are correct. The control lever separates the spring and the guide pin. This means the guide pin can't fall out of the housing, and it should be too long to fall into the boost compensator housing.


The LCCOL instructions i think are a bit confusing. Also written a long time ago now and a bit generic. These pumps are better understood by more people now. There's good info in the "official 1HD-T pump tuning thread" if you have time to read it. Start from about page 40

the control lever acts on the governor spring and lever inside the main body of the pump. If you remove the top of the pump (boost compensator housing) as @davegonz suggests, you need to be careful not to stretch, or dislodge the governor springs

 

[JSparks]

Thanks heaps, I have decided unfortunately to tow it into the mechanics tomorrow with my TDI discovery of all vehicles (the shame). I don't want you guys to think I've given up or don't appreciate your input massively but I'm back to Auckland tomorrow for work and don't have the time or balls to dig much deeper into such a crucial part of the engine without a better understanding of what I'm doing.
I am currently in Thames NZ a small costal town at the in laws, I will be running through everything and passing the link of this thread onto the mechanic so please keep the ideas coming and I will update you all with the diagnosis from the mechanic.
worst case its about $2400nzd for a full rebuild of the pump which would suck, currently 315,000 km on the pump.
best case someone in the know pulls it apart and gets it sorted.

Mudgudgeon I have been reading it prior to starting all this and during but am not yet up to page 40, the reading will continue when my 5 month old lets me

Davegonz thanks heaps, I am interested in how the governor works differently on NA and turbo pumps, the governor seems key to all of this which if connected to the compensator would directly affect rev limits, this would mean that the the compensator would be a key component of the issues I am having.
for example if the governor spring broke or jammed could that be holding the revs at idle?

 

[JSparks]

just for context, this is what we are working on and this driveway lined with rose bushes is the closest thing I have to a garage.

 

[mudgudgeon]

Hope you get it sorted without to much pain.
Nothing worse than trying to trouble shoot away from home.

The boost compensator works with the governor lever. It limits how far the governor can move when off boost, and allows the governor lever to travel further toward maximum fuel as boost builds.

 

[96TrailSurfer]

just for context, this is what we are working on and this driveway lined with rose bushes is the closest thing I have to a garage.

View attachment 1875217

Hey man, did you every get it sorted out? I seem to have a similar issue and no solution yet