1HD chugging at low rpm, medium throttle input (1 Viewer)

[Turbobrick211]

Good morning Diesel People!

I just finished up installing a freshly rebuilt injector pump and injectors, along with water pump and drive belt on my '92 HDJ81 cruiser. I set the timing to 1.36mm using the dial indicator tool, and once all connected it fired right up! It even idled perfect, right outta the box! I was pretty pumped. After a couple test drives, I have noticed that at lower rpm in 2nd or 3rd gear, with maybe 1/3rd throttle, it chugs. And what I mean by chugs is that is does a somewhat rapid surging of the engine and doesn't have as much power. If I give it more throttle it will get through it and run fine. But it's kinda driving me crazy. I have tried giving it a little more, and a little less fuel, but it is still there. I have not tried adjusting the timing yet, but I feel that is next on my list. I kinda feel like it needs a bit more timing, as I am only getting about 10psi boost at full throttle, where as before I had the pump rebuilt, it would make a solid 14-15psi boost.

I just wanted to check here to see if anyone else has had this chugging issue, and fixed it with timing. I hope to play with the timing after work today, and will report back with an update.


As usual, thanks for the help friends! It sure is nice driving the diesel again!

Eric

 

[mudgudgeon]

Does it blow white smoke at the same time as chugging?

 

[Turbobrick211]

Does it blow white smoke at the same time as chugging?

Not that I have noticed, but I wasn't looking for it. I'll have to keep an eye out when I drive it next. I did increase the timing just a hair with no real difference. I also gave it a tiny bit more fuel with no real change. It only happens when I'm in boost, around 5-7psi. If i push the pedal down more and get it to 10psi it feels fine. Wondering if I need to adjust the boost compensator a little bit.

 

[Turbobrick211]

I did some more fiddling with the IP. I lowered the star wheel about 10 clicks after counting 48 clicks from the bottom. I verified that the aneroid pin was at the deepest contour like I had it set before. I turned the cam plate in the cover to it's thinnest position and gave it a tad more fuel. It runs real strong, but still does the chugging/shuddering between 1600-1800 rpms and 5-7psi boost. Also, I can only get 12psi max boost out of it where as before I was hitting 15psi no problem. I have not ever touched the wastegate rod to increase the boost, just fueling. Any thoughts on this shuddering? It's driving me nuts.

 

[Turbobrick211]

While driving home today, I was thinking about the other post talking about a misfire, and the poor fellow who ended up finding several sets of copper washers under his injectors. I couldn't for the life of me remember whether or not I removed copper washers when I pulled out my injectors, and thought maybe that was my problem. So when I got home, i pulled out the injectors and double checked. I was really hoping this was my problem. But alas, I had removed the old washers. I turned the fuel back down a little, and now I don't have any black smoke, but white smoke when in boost. And now it only makes 10psi boost instead of 12. I am thinking I need to up the timing some more. Or play with the star wheel some more. Any thoughts? Also, my EGT's are pretty low. Cruising at 65mph, they are around 500-550. If I am bombing up a hill, they only get up to around 650. Before the rebuild, I would be around 700 at 65mph, and 1200 bombing the same hill. Does that mean I have too much fuel? Not enough fuel? Or that my pump and injectors were so bad before that it was running lean? I'm fairly new to EGT tuning.

 

[roscoFJ73]

Have you contacted the pump rebuilder? That's where I would go before altering the adjustments etc

 

[Turbobrick211]

I will contact the rebuilder today to get some input. I tried a little more last night. I wanted to advance the timing a bit more, but realized that it was hitting the end of adjustment on the slots in the housing, so I can only get 1.38mm of plunger stroke at full advance, which is lower than I had it setup at before removal. Does anyone know how much timing is changed with one tooth on the belt? I verified that I had all the notches lined up on the pulleys and the belt when I installed it. Just curious. I actually retarded the timing a bit last night just to see how she runs. It is a little less responsive off the line, but still runs great and makes pretty decent power. However it still has the chugging feeling at the same rpm and boost levels as before.

 

[Turbobrick211]

Bump. Anyone? Pretty sure a bunch of you know a lot about these pumps.

 

[veiloctane]

when I had my fuel pump rebuilt it also was chugging along and when turning it would stall out in low RPM.

all that was needed was to turn the full load screw 1/4 turn (there may be a protective cap on it to pry off)

if you want timing I know there is a way to do it by ear other wise you can use a special tool

TIMING TOOL - AS SEEN ON TIMING A VE FUEL PUMP | Denco Diesel and Turbo

***AS SEEN ON OUR TIMING INSTRUCTIONAL VIDEO*** Use this tool along with a dial gauge (available at any auto shop) to assist you in timing your VE Style fuel pump. **Dial gauge must have minimum 5mm travel. PART NO: 95095-10400 ***Download the VE Pump timing specifications***

www.dencodiesel.com

 

[roscoFJ73]

Does that mean I have too much fuel? Not enough fuel?

It would be in the colour and amount of smoke. Too much fuel would making clouds of black smoke. Lean usually makes white smoke, not sure about this situation though.
Have you verified there are no air bubbles in the fuel?

I would be wary of altering the pump too much, pump rebuilders have been known to use that as "get out of jail free card" when their work is in question.

 

[veiloctane]

I will contact the rebuilder today to get some input. I tried a little more last night. I wanted to advance the timing a bit more, but realized that it was hitting the end of adjustment on the slots in the housing, so I can only get 1.38mm of plunger stroke at full advance, which is lower than I had it setup at before removal. Does anyone know how much timing is changed with one tooth on the belt? I verified that I had all the notches lined up on the pulleys and the belt when I installed it. Just curious. I actually retarded the timing a bit last night just to see how she runs. It is a little less responsive off the line, but still runs great and makes pretty decent power. However it still has the chugging feeling at the same rpm and boost levels as before.

Tuning by boost and EGTs alone will only get you part way. But it's a start.

Tuning with AFR and air density/flow in combination will be more accurate.

Usually too much black smoke is unburnt fuel.
I've got a quick puff of black smoke for a quick moment and clears up completely around when boost kicks in.

 

[Turbobrick211]

Thank you for the replies!

I have no air in the fuel line. I fixed that problem a few months back by replacing the fuel filter housing/primer pump which had a torn diaphragm. I have adjusted the fuel screw in a little which helped. Last night I turned the cam plate on top of the boost compensator 180 degrees, so now it is at the highest point of the ramp instead of the lowest. This has helped a bit. I will probably try a few other adjustments on this to see how it responds. I also turned the star wheel counterclockwise about 7 clicks, which also seemed to help a little. But it still has a chugging at the same rpm and boost levels as before. The thing that strikes me as strange, is that I cannot get as much timing out of it as I had before the rebuild. I don't know enough about the inner workings of the pump to understand why this would happen. Perhaps a different governor spring was used? I don't know.

 

[veiloctane]

Any info here will help?

I’ve uploaded a FSM for the ve pump a while back in the diesel FAQ section.

Post in thread 'DIESEL TECH FAQ'
FAQ - DIESEL TECH FAQ - https://forum.ih8mud.com/threads/diesel-tech-faq.924038/post-14402255

 

[mudgudgeon]

Does anyone know how much timing is changed with one tooth on the belt

Timing belt has no bearing on pump timing.

Pump timing is set by gears driven from the crank.


In regards to smoke, black smoke is due to overfueling, rich air fuel mix and incomplete combustion.

White smoke is due to unburnt fuel or raw fuel. Unburnt fuel can be the result of incorrect timing ( badly retarded)
Or, commonly due to air in the fuel system which retards timing.

There's a sticky describing different smoke colours

Post in thread 'Diesel smoke questions? Read this first!' Diesel smoke questions? Read this first! - https://forum.ih8mud.com/threads/diesel-smoke-questions-read-this-first.273850/post-4267470


My HZJ105 had air getting sucked into fuel lines, and would chug and stumble at around 2k rpm.
It got worse and resulted in white smoke at the same time.
White smoke is due to raw fuel burning in the exhaust. It stinks heavily of diesel.

Have you done anything to confirm there's no air in the fuel system?

 

[Turbobrick211]

Timing belt has no bearing on pump timing.

Pump timing is set by gears driven from the crank.


In regards to smoke, black smoke is due to overfueling, rich air fuel mix and incomplete combustion.

White smoke is due to unburnt fuel or raw fuel. Unburnt fuel can be the result of incorrect timing ( badly retarded)
Or, commonly due to air in the fuel system which retards timing.

There's a sticky describing different smoke colours

Post in thread 'Diesel smoke questions? Read this first!' Diesel smoke questions? Read this first! - https://forum.ih8mud.com/threads/diesel-smoke-questions-read-this-first.273850/post-4267470


My HZJ105 had air getting sucked into fuel lines, and would chug and stumble at around 2k rpm.
It got worse and resulted in white smoke at the same time.
White smoke is due to raw fuel burning in the exhaust. It stinks heavily of diesel.

Have you done anything to confirm there's no air in the fuel system?

I am confused. You say pump timing is controlled by gears from the crank. There is a drive belt which drives the pump off of the camshaft gear. So there IS a possibility of getting the pump timing off a tooth. Which is why I was asking how much timing change would one tooth difference make?

Yes, I have verified no air in the fuel supply using a clear hose. Does not get air sucked in. I had the problem in the past due to a torn primer diaphram. But I replaced the filter housing and solved that problem.

Lately I have also noticed that it doesn't run that smooth at lower rpms either. It is almost as if every other piston pulse is weaker than the other 3. I mean you can hear it in the turbo sound when driving past a wall. A very light Choo choo choo, instead of a nice smooth whoosh that the turbo normally makes. I'm wondering if there is something up with the governor, or maybe the cam plate and rollers. I don't know. Still haven't heard back from Diesel Fuel Injection Service in Portland.

 

[KiwiDingo]

I mean you can hear it in the turbo sound when driving past a wall. A very light Choo choo choo, instead of a nice smooth whoosh that the turbo normally makes.

Are you sure it's not a wastegate issue? What you described above sounds very much like the gate chattering when it starts to open which is quite a common issue.

 

[mudgudgeon]

I am confused. You say pump timing is controlled by gears from the crank. There is a drive belt which drives the pump off of the camshaft gear. So there IS a possibility of getting the pump timing off a tooth. Which is why I was asking how much timing change would one tooth difference make?

Pump is absolutely gear driven.

The cam is driven by a belt, the cam drive pulley is bolted to the pump gear

The torque required to drive the pump is way too much for a narrow belt. The pump injects fuel at 2200+ psi.
As a comparison, a large supercharger compressing air to 15-ish psi uses a 2" wide toothed belt.

Yes it is very much possible for the pump gears to be misaligned.
If you installed the pump, it may be worth checking you got them aligned.

I think a call to the pump rebuilder first would be worth while.
Assuming you were happy with their service, have a chat to them about how it's behaving and ask if they have any advice.


Edit, I see you've tried calling the pump guys. Persisting with that might save pulling the timing case off.

 

[Turbobrick211]

Okay, yes. I did some more searching and found a diagram of the gears driving the pump. Thank you for teaching me something new! Okay, so there is no way that I could have gotten the pump installed wrong. Which means I'm even more confused at why I cannot get as much timing out of it as before it was rebuilt. Back to the drawing board.

 

[mudgudgeon]

Okay, so there is no way that I could have gotten the pump installed wrong

If gears were assembled wrong (match marks not all aligned) then pump timing can be off, for sure.

 

[Turbobrick211]

If gears were assembled wrong (match marks not all aligned) then pump timing can be off, for sure.

Well, I didn't pull the gears off, nor did I open up the gear housing. I just pulled of the oil retainer plate to get to the water pump, and pulled the injector pump. I double checked and made sure that the key was in the groove as it should be.