I just pulled the top from the AFC diaphragm on the son's truck.

I had my printed instructions laid out on the bench.

I looked at the next step : Remove the diaphragm/fuel-pin.

Okay, so far so good.

Next : Remove the SPRING.

What spring ?? There ain't no spring !!!


There was an inch of crud all over everything, with no evidence of any screws being messed with in years, so it is untelling how long the spring has been missing in action.


Of the four Cummins trucks we have, it is probably the strongest running one of the bunch; so, I can see no negative effects, running-wise, due to the springs absence.


What bad could be happening due to the lack of this spring ??




What is the correct Bosch part-number for a replacement ??


Thanks.

 

bad fuel economy without the spring nothing to keep the diafram from being all the way down all the time, should of had lots of smoke until the turbo spooled up unless it was set at the lowest point, which would still smoke

 

The funny thing about that is this truck probably out-mileages the others.




^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 

Does anyone know the part-number ??

I'm about to put it all back together.

Thanks.

 

There are 2 different p/n's for the spring, one has more spring rate than the other from what I gather. The color of the spring has been discussed here and there but not the p/n's! I'll be corrected if I am wrong I'm sure. There is also a plastic spacer bushing between the spring and the diaphragm, and there are 35 different p/n's for it! Thickness being different on these. I would give the local bosch racketeer your pump p/n and get the spring and spacer for it. Here's the two different spring #'s

1 464 618 652 compression spring
1 464 618 651 compression spring

That spring is missing because someone had performance enhancement in mind.

 

Thank you.

There is a plastic sleeve over the fuel-pin, about 5/8"-long; is that the plastic bushing you refer to ??

I guess a slightly wrong spring would possibly be better than no spring at all for a heavy-towing non-IC truck, right ??

I had no idea the spring was absent, the engine acted no different than any of the others.


That gear-wheel where the missing spring sits on seems to be about as far down as it can go; what does it do ??

Thanks.

 

its the adjustment for spring pressure on the diafram, farther up it is the more boost it takes to push the diaframe down.

 

I just "borrowed" the spring out of a spare engine.

This one is bright metallic green on one half (lengthwise) and sort of olive on the other.

I am almost positive it is a factory-original; that engine is a non-IC.

This will give me time to order a replacement.

Thanks.