When do I worry about runaway?

[Begle1]

When do I need to start worrying about my engine running away?

In preperation for my Goerend's, I turned my full power screw 1 turn, turned the starwheel 180 degrees, turned the fuel pin close to the deepest setting, put two turns on the smoke screw and adjusted the idle back to normal.


So, um, anyways... When do I worry about runaway?


And, on a tangent, when do I worry about the solenoid giving out?

Thanks.

[PToombs]

If you turn the fuel screw in too far it can run away. Some trucks will, some won't. When you turn it in if it kinda floats when you blip the throttle, it's on the edge.
The solenoid won't really go, it's the plunger. When you push alot of fuel, it will "chip" the rubber on the end. Then you are back to the manual shut off option!

[Begle1]

Well, I installed a cable shut off today. Think I need to modify it a bit later, but it's functional.


From what I gather, pumps can turn anywhere from 2 to 6 turns before bottoming out... Runaway can likewise occur anywhere from 2 to 6 turns. If runaway occurs at 2 to 3 turns, there's a good chance the manual shut-off will kill it, but if you are only seeing runaway at 4-6 turns then you'll probably require the 2x4 over the turbo.

To determine if you're about to see runway, take the RPM's in neutral to around 2400 RPM and hold the fuel pedal; if it creeps up on it's own, then you're close. Another test is to drop the fuel pedal from 2400 RPM; if the RPM's decrease only slowly, then you're close.

Accurate information, marginal or left field?

With one turn on the power screw I saw my WOT boost increase from 20 PSI to 24 PSI. My EGT's went from crappy-Autometer-position 1 to to crappy-Autometer-position 2.
This average or anemic?

[gman07]

From what I've read, runaways usually can't be stopped with the shutdown. You'll need a board or piece of metal to block off the turbo.

It sounds like you got pretty good results with only one turn on the screw. (well, without knowing EGT's, anyway)

The runaway-testing procedure sounds accurate to me.

[dpuckett]

Begle1- your bost numbers sound about right for one turn on the screw.

As for the runaway, my last 2 pumps (along with Bill Gilbert's 89) have taken off on their own in neutral from about 18-1850rpm, and gone fast to the governor. But, when I let off, RPM came right back down. On a side note, the 290 BCIII I drove on the farm did the same thing in the lower gears when empty- got to a certain point and ran up on its own when holding pedal steady. Going 25mph through town took a lot of attention and pedal feathering. I think it is just the nature of the beast, esp when fuelled above stock.

Daniel

[Falcon]

I only have 1 turn on the screw and I get 30 lbs of boost, but I do have a fuel pin installed would that give me the extra boost #'s. Before I installed the 366 spring and the fuel pin I got 20lbs of boost after I installed them and setting the guv., turning the fuel screw 1 turn I get 30 lbs easy. With the hx-35 I only see 800* on the pyro.on a good romp and climbing long grades. I also want to turn in the screw 1 more turn, But will remove the intake and have a clean 2x4 ready just in case.

Greg

[swank]

you can start worrying about a runaway whenever you want!! it didn't even cross my mind until i was holding a broken shutoff cable in my hand while i was sitting in the driver seat with the truck on the dyno and about 20 guys standing around. thought A LOT more about it while i was standing with my head about 3 feet from the engine, holding the shutoff lever to keep rpm's at about 3000 while everybody else was running around the shop trying to find a way to get the filter off. once that happened, it took another 30+ seconds for everybody to NOT find something big enough to cover the big turbo inlet. once that failed, somebody cut the cold pipe boots and put something over the little turbo. one guy said he was looking in the window and saw the 4000 rpm tach get BURIED.

[Begle1]

If you were to manually shut off the fuel during a runaway, by cutting off the fuel line before the injection pump, how long would the fuel in the pump and lines last before running out?

Or would running the fuel out like that be too hard on the injection pump?


Ever see the spring loaded guillotines that the sled puller guys have to run? I might just have an industrial source for those; could end up installing one on an ole' smokey BHAF mount some time soon.

[swank]

i have heard of those and would love to install one. i personally don't think that sucking the pump dry would be doing it any favors, but i really have no idea as to what would actually happen. i think kta has seen the inside of a pump or two that had that happen though. maybe he can tell ya more.