Free-revving pump

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bubba_pa

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Oct 30, 2007
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installed a 180 pump 5K GSK, 0 plate, Mack rack plug, AFC mods and previously turned plungers and barrels. The pump was just gone over at a reputable local Bosch shop. The control rack was stuck from sitting too long but nothing else seemed to be wrong. Installed the GSK with one engagement and then 4 harder clicks. Revved smooth and idled fine.

After installing it I took it for a test drive and everything seemed okay with an easy pedal but when I punched it hard the thing just took off and kept revving. It shut down with the key (luckily) but when I tried to start it again (after working the throttle linkage back and forth) it free revved to way North of 3500.

I took the AFC off and when I pull up on the fuel shut off solenoid, the control rack and throttle linkage move forward. The fuel shut off will move it back but it is under tension.

If a plunger were stuck or one of the ball bearings that keeps the control rack in place were dislodged I would think that the rack would not move at all. I haven't had time to check the GSK to see if one of them is hanging up or not.

Is the having the barrels turned up and the Mack plug too much rack travel and something is binding up? Or, has something bound up the governor weights or springs.

It almost seems as if the rack is moving into a "cold start" position full forward. It scares me to try it for fear of it not shutting off.

Any help and ideas please send em in. Just glad it didn't happen at a pull!
 
If you do start it, just keep a garbage bag by you so you can throw it over the air filter.

I cant give you any ideas, except to take it to the shop who benched it.
 
The only use for a plastic bag woould be to clean up after I c**p myself. This thing took off so fast when I tried to restart it that as soon as the starter engaged and I could get it shut off it had already hit 3500. Time for an air and fuel shut off in the cab.
 
Sounds like somebody slipped you a VE pump by mistake. :lolly:
 
There is some movement of the rack. The fuel shut-off lever will pull it back on it's own. But when I manually lift up the shut off, the control rack and throttle lever will move forward as if it's under some tension. Am I correct in thinking that if the rack where completely stuck the thing wouldn't shut down on it's own?

It's going to have to come off one way or the other. I'd just like to have a better idea what's up with it in case so when I do take it off I don't undo what is binding and they can't find out what's wrong.

I'm thinking there may have been too much rack travel with the Mack plug and the barrels having been turned up. It's timed at 26* now.
 
Who's GSK? I thought the 5k's didn't need that many clicks after initiation. Maybe try backing it off a click or two to see if it quits hanging.
 
Tate said:
Who's GSK? I thought the 5k's didn't need that many clicks after initiation. Maybe try backing it off a click or two to see if it quits hanging.
Click to expand...

Good point tate.

Now that you mentioned that. Most of the 5ks are 1 soft 3 hard clicks.
Did you remove the seats? What shims are in there?
 
bubba_pa said:
Am I correct in thinking that if the rack where completely stuck the thing wouldn't shut down on it's own?

I'm thinking there may have been too much rack travel with the Mack plug and the barrels having been turned up. It's timed at 26* now.
Click to expand...

You are correct in thinking on the first comment, but not the second.

If the rack is stuck (b&p), you''ll have to kill air to the engine to shut it off.

The only way there could be too much rack travel is if the pump shop slotted the rack for even more forward movement (I highly doubt this was done). If this was done, the rack would go full forward and not come back because the control units would rotate out of place in the rack.

Sounds like a governor problem to me $.02
 
tony597fitter said:
Good point tate.

Now that you mentioned that. Most of the 5ks are 1 soft 3 hard clicks.
Did you remove the seats? What shims are in there?
Click to expand...

If I remember they are Haisley's 5 K's (which ever Pure Diesel Power sold a two years ago).

There are no shims under the inner three springs. Not sure if any under the large idle spring. When you say "seats" do you mean the post that the smallest inner spring sits on or the shims under the inner three springs?

CTDYoungGun I'm agreeing with the thought on the governor as well since there is still movement with the rack and I could shut it down with the fuel solenoid. I suppose there could be a small part hung up in the governor assembly too.

But did it run nice for a few moments!
 
from what i kno when you do a gsk you dont wanna go by clicks on the studs, do it by check the stud protrustion with a set of calipers. try like .050 and work from there cause i know if there too tight it will cause the rpm to rise at idle cause the idle spring is the same i think on the gsk kits (correct me if im wrong) so you should have the same amount of tention on the as stock. with it free revving like that i would say your rack is either stuck or maybe your springs are hanging up or something.


again correct me if im wrong but thats what ive learned

hope this helps
 
My 5 k in a 215 pump has given me a high idle a couple of times. But it seems To hang up around 2300. I have just driven it a bit and it freed up.
 
Timebomb - not in PA, I am a Physician Assistant (PA). I'm west coast of Wisconsin.

I havent' gotten out to do anything more but after looking at posts and a Bosch tech manual I'm more confident that the governor weights and/or springs are hanging up. It is definitely not drivable.

Since the pump was just rebuilt I don't want to take it back off, but if there is a small washer or clip left behind that could bind again I'd like to know. I'm going to take the GSK out and see if the weights move freelly and then go from there. I think it should probably come back off and be rechecked again ($$$). I'll post up results. Thanks for all help.

Paul
 
Final outcome - the throttle linkage was hanging up on the outside of the pump case. Never noticied that it was in backwards (needs adjustment threads at rear of pump). The truck had the throttle rod recall done 10 years ago and I never changed how it came on the truck.

So far pump seems to be running better than ever. Thanks for all help.

Paul
 
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