Adjusting the tension on the MFI pump drive belt

[speedo]

I don't see it covered in "Check-measure-adjust"...is there a simple way to set the pump on its pedestal for correct tension? Normally I would just call Grady...can't do that anymore. : (

Speedo

[SpawnyWhippet]

Am also hoping someone knows this, as I am bolting my MFI unit back onto my engine tomorrow and the belt tension was way way too loose before I removed it.

[edmayo]

The proper belt tension is 'taut' but NOT 'tight' At the correct tension you should be able to turn the belt 90 degrees midway between the pulleys. You also need to rotate the engine several turns to see where the belt positions itself on the pump pulley, if the pump is angled wrong the belt tries to 'walk' off the pulley. Now it won't come all the way off, but it could run a 1/4" or so off the edge. If it does just keep changing the 'yaw' of the pump until the belt stays all the way on the pump pulley.

[SpawnyWhippet]

Perhaps I have the wrong belt, I have adjusted the pump as far from the cam pulley as I can get it, but there is still too much slack in the belt. I can easily rotate the belt 180 degrees at the midway point.

I'll order a new one (999-192-030-40-M51) and see if that fits better.

[SpawnyWhippet]

I replaced my belt and the new one is the right size.

However, I am trying to align the fuel pump sprocket with 40 deg after TDC for cylinder 4 and noticed that my fuel pump pulley has 2 sets of markings about 160 deg apart. One is a nicely inscribed (factory) dot punched in the face, the other is a pair of lines scribed less nicely. Which of these is likely to be the timing mark?

In the attached pic, the 2 lines are at 12 o'clock and the dot is about 5 o'clock on the pulley face

[Richy]

The mark is a line on the hub that holds the pulley . I think you should buy a manual .

[SpawnyWhippet]

I found the mark on the hub, it was disguised by a blob of oily rust. After I cleaned the hub, the line was visible and aligned to the dot punch on the pulley. Problem solved, thanks Richy

[edmayo]

There are alignment marks on the hub and pump, the marks on the pulley don't count, you are aligning the hub to the pump housing. The pulley itself is immaterial.

[SpawnyWhippet]

Thanks Ed, I realised this later after I uncovered the alignment mark on the hub. This was precisely matched up to the punched mark on the pulley. I was unable to get my FE timing mark exactly aligned to the fuel injection pump alignment marks due to a slight offset of the teeth on the belt with the toothed pulley. It is maybe 2-3 degrees out. How critical is this?

[edmayo]

That is why I said the pulley is immaterial, you align the mark on the hub to the reference mark on the back of the pump,,,,,,then for a fine adjustment if needed you loosen the three allen head bolts holding the pulley to the hub and move the pulley while holding the hub, to allow the toothed belt to line up and slip on.