Yes, another rough running, smoky 1-hdt (likely fuel delivery) (1 Viewer)

[dan1554]

This has finally gotten so bad that the vehicle is undriveable. It stutters, has problems idling, and belches white smoke. I think there is an air leak somewhere, and want to get opinions.

I opened up the fuel tank and the strainer looks clear, no black schmoo. Still, it looks like the IP is barely getting any fuel.



Soon after that video ends the engine starts to sputter as the IP picks up air. If I pump the primer the engine revs come back up and all is well for 20 seconds or so, until it gets starved for fuel again.

I'm also curious what this thing is on the fuel filter housing. It emits fuel and air bubbles after I pump the primer a few times, and Im wondering if it might be the culprit:



I'm really leaning toward it being the fuel filter housing. As I understand from other threads, it needs to be replaced and cannot be repaired. Does this sound right? Does my diagnosis sound legit?

 

[DancesWithMutts]

I can't comment, on your diagnosis, but my fuel filter worked it's way loose once, and the truck was sputtering and smoking and dieing.

 

[mudgudgeon]

not sure what that bit is on the filter housing that's leaking, but yes, that looks like the source of your problem.

bypass the filter completely with a bit of clear hose from the hard fuel line, directly to the IP, if the bubbles are gone, and your splutter is gone, the problem is at the filter housing. Pre-fill the clear hose with fuel first to eliminate as much air as possible while you install the bypass, as you wont be able to use the hand pump to prime the hose. Any air in the hose should clear itself fairly quickly

 

[roscoFJ73]

Sometimes its just the filter not sitting in the filter head properly. Remove and reconnect. 90% of air leaks will be in the engine bay and its usually fraying rubber or old clamps.
Try Mudgudgeons suggestion OR add some fuel line before and after the fuel filter.
Those filter heads are long lasting if they haven't had the guts pumped out of them by owners who pump them everyday in preference to fixing a leak. Theoretically they only need to be used once or twice a year, so they don't wear out quick.

 

[diesel80]

I've had exact same thing but under load. Appears the filterhead was letting air in.

 

[mudgudgeon]

Sometimes its just the filter not sitting in the filter head properly. Remove and reconnect. 90% of air leaks will be in the engine bay and

Definitely worth checking these first. Almost zero $$ cost. The fact you have fuel Bunning out is not a good sign. My HZJ105 had a leaking filter/primer assembly, there was absolutely no sign of a leak, but it was sucking in air

 

[IanB]

That bit on the fuel filter housing is the heater element for the cold weather package, and it's definitely a problem to be leaking like that. There's a couple o-rings on the heater element you might be able to replace, you can see in the pics in this thread:

For Sale - 80/81 Series Brand New OEM FUEL FILTER CAP and HEATER

 

[dan1554]

Thanks guys! I am in the process of tracking down a new heater assembly. The plastic housing is brittle and snapped during removal. If anyone is wondering, there are 4 o-rings of varying sizes, two outside and two inside the plastic.

 

[roscoFJ73]

Do you really need it in Denver?

 

[dan1554]

Im guessing there are additives applied to winter fuel that prevent gelling. So maybe not. Not that it doesn't get cold here on occasion.

 

[mudgudgeon]

Im guessing there are additives applied to winter fuel that prevent gelling. So maybe not. Not that it doesn't get cold here on occasion.

View attachment 1602968

Looks like Christmas eve should have been a skiing day!

 

[dan1554]

@mudgudgeon Not with these hobbit feet!

 

[dan1554]

Well it wasn't the fuel heater. I went ahead and replaced the line behind the filter with clear, and it is all fuel, no air. I replaced the filter with a Wix I had sitting around, and there was a definite improvement. There is more fuel and the IP no longer pulls in air. Either the previous filter was not seated correctly or there is an issue with the water sensor.

While that particular issue seems to be resolved, the upper half of the hose between the filter housing and the IP is still air that I can't seem to make go away. Is this normal?

 

[roscoFJ73]

Is this normal?

Not to my recollection. Have you checked the ends of the fuel line? They often get small cracks and let air in. The water sensor has an O ring, but its not normally a problem. You can also try pumping the bubble through the injection pump while its running. It shouldn't come back if its leak free.

 

[dan1554]

Thanks, I will give that a shot. Past that I can only imagine it being the pump housing.

Still diagnosing the smoke, it is belching unburned diesel pretty good. Going through a compression test now, and if that is within spec (fingers crossed!) I will probably ship off the IP for a rebuild.

 

[mudgudgeon]

the upper half of the hose between the filter housing and the IP is still air that I can't seem to make go away. Is this normal?

Nope.
It should appear full of fuel IMO



This shows a loop of clear hose from after the filter, to the IP when my filter housing was sucking in air with no visible indication of a leak. Bypassing the filter housing, it ran like a top, and hose stayed "full"
I used about 1metre of hose, left the hood just latched on the first stage of the latch and went for a drive.
Every time you see a bubble, my engine would flat spot, or stumble badly, and puff white smoke that stink of raw fuel

Watching that again, I can hear the flat spot in the engine RPM.

 

[roscoFJ73]

I will probably ship off the IP for a rebuild

How long since the injectors were done? If the pump does need major internal work ,its strongly recommended to do the injectors at the same time.

 

[mudgudgeon]

I was all set to pull my IP out and send it away. I'd rebuilt injectors, checked pump timing, new filters, nothing to suggest compression wasn't good etc etc.
Hand primer was still priming just ok.

A $10 piece of hose fitted in the hardware store car park on my way home from work saved me a $2000 pump rebuild.

 

[dan1554]

How long since the injectors were done? If the pump does need major internal work ,its strongly recommended to do the injectors at the same time.

Injectors are brand new. After I did this, black smoke was reduced pretty significantly but unburned fuel remains near idle.

I was all set to pull my IP out and send it away. I'd rebuilt injectors, checked pump timing, new filters, nothing to suggest compression wasn't good etc etc.
Hand primer was still priming just ok.

A $10 piece of hose fitted in the hardware store car park on my way home from work saved me a $2000 pump rebuild.

Thats a pretty clever way to check fuel flow while driving. Once I get it back together post compression check I will do the same. Grateful for the troubleshooting tips - last thing I want to do is blindly throw money at it.

 

[roscoFJ73]

Injectors are brand new. After I did this, black smoke was reduced pretty significantly but unburned fuel remains near idle.

Injectors are best matched to the pump pressure and different markets have different cracking pressures to suit the local emission standards. From memory there are 3 different cracking settings for 1HD T injectors.
Pumps don't normally need too much internal work until they have 300000klms on them and often closer to 400000.
Worn pumps usually begin to lose pressure at higher rpms when they a fully warmed up.
I would be reluctant to a send pump off unless I know its the culprit for sure. Ask for a bench test first.