8k fuel problem

[8k bill]

my 1980 8k starts and runs good when cold but as it warms up it develops a flutter and puffs black smoke. engine was fully rebuilt.sounds like pump or gov prob. any idears

 

[kbeen]

can you crack the fuel lines loose one at a time and see if it is one cyinder possibly causing the problem. may just be a injector nozzle.

 

[8k bill]

hi kbeen, all nozzels were replaced new from cat.did the crack test but didnot seem to make any diff. one old fella told me it could be a weak gov spring?

 

[Bob/Ont]

hi kbeen, all nozzels were replaced new from cat.did the crack test but didnot seem to make any diff. one old fella told me it could be a weak gov spring?

The weak spring isn't the governor spring. It's a worn horseshoe drive spring between the camshaft and the governor drive gear. change spring and both dowels.
Later Bob

 

[Old Magnet]

Hi Bob,
Good to see you found your way here.
Here's a picture to go along with the post. Items 27, 32, 34 is what is being referred to:

 

[Bob/Ont]

He needs two of 32(dowels) and spring 34. Thanks for the pic OM yes looks like a nice site here.
Later Bob

 

[Old Magnet]

Hi Bob,
My parts book calls for one #32 and one #30. They are listed as separate line items but turns out they are the same part number. Thanks for the correction.

 

[Bob/Ont]

Pete, I wasn't sure that #30 went into the cam end from the pic. just knew they were the same part#.
Later Bob

 

[8k bill]

Pete, I wasn't sure that #30 went into the cam end from the pic. just knew they were the same part#.
Later Bob

thanks heaps you fellas, i will get my machanic to have a look at the spring. will let you khow how i get on. Thanks again bill

 

[Bob/Ont]

Bill, if you take the cover off the end of the rack and hold a pencil in there to steady the rack movement while it idles you will see the problem, the rack is pulsing.
Later Bob

 

[Old Magnet]

The "spring" is actually a rather clever coupling and pulsation dampner to shield the rather sensitive governor from the pulsations of the injection pumps. Although it works it is apparently very sensitive to any wear of the spring seats and dowels......seems to be a fairly common occurrence and replacement makes it right .

 

[D6 Merv]

when you take the pump off; check the condition of the pump drive tang.
when that spring wears and causes the engine to hunt, this often causes the drive tang and slot to wear and then snap. easy way to check is apart from visual, timing will be out. This problem is more common on japanese built 3304/6 with interim scroll DI motors; but did see this on a early D8K once too.

 

[JeremiahSr]

does that engine have a turbo charger? if it does and the shaft an bearings try to seize or slow down when hot would give same problems you are having. black smoke does not have to be excess fuel...it could be lack of air as well.

 

[rabia]

I think replacement is a good option. You can also consult with some professional.

 

[DPete]

I had one do as you describe, puffing black smoke at idle, the cam drive on the fuel pump was sloppy enough to change the timing as mentioned above. I think we put new pumps, cam and went thru the governor, seems like $5K rings a bell, I know it wasn't cheap.