FL 120 shutdown solenoid

[RFA]

I started my 1972 Ford Lehman (Simms fuel pump) today after the winter layup. As usual it started in seconds and ran with no problems at the dock.
After 30 minutes I pushed the stop button and nothing happened, the engine just kept running at idle.
I checked the stop solenoid and it was operating with each push of the stop button and I even pushed the solenoid in by hand and the engine still kept running at idle.
I closed the fuel shut off taps at my primary fuel filters and after a few minutes the engine stopped.
I started the engine again and had the same problem.
Does anybody have any ideas? your advice would be most welcome.
Thank you
Roger

 

[alfamike]

FL - diesel won't shut off

FL-120 - Keep running after STOP button pressed.


Quick question ? - when did you last change your injection pump oil ? If it is more than 50 hours - this can be your source of the issue as the rack will stick. That said we can also look at a couple other things.

I am no Ford Lehman expert, But I do own one, but Sounds like you need to check a couple things. The rest of you FL-120 experts please chime in as to what they think this issue is.

I believe the "STOP" button your pressing sends a 12 volt signal to turn off the fuel. However you said the solenoid was moving, however it still did not stop. Even when pushed by hand. So probably not electrical issue.

The shut off solenoid operates a shut off valve or in some cases moves the fuel inj. pump control rack to the off position, others shut off fuel with it's own special fuel shut off valve.

It sounds like that valve is not closing probably due to some mechanical reason or more likely the FI rack is not moving fully to the shut off position & is sticking to such a point that the shut off solenoid can't move it. May have gone to long with out changing the INJ pump oil.

In either case, it sounds like it is an "on engine" fuel injection pump or fuel shut off valve issue.

So start there first.

Good luck.


Alfa Mike

 

[RFA]

Alfi,

I removed the side cover from the injector pump and inspected the rack inside the pump.
It is moving freely, right and left without friction when moved by hand.
When the stop solenoid is activated the rack only moves about 1/8th of an inch to the left, still leaving a 1/4" of play.
I did remove the stop lever arm from its splined shaft and added a few degrees of rotation to gain a bit more of travel of the rack. After starting the engine again the stop button could almost shutdown the engine but by giving the stop solenoid a finger push it would work.
So my question is, how much movement of the rack is required to initiate shutdown?
Also I would like to know if anyone has an idea as to why my Simms injector pump would suddenly be out of adjustment. All external mechanical connection look correct.

Thanks,
Roger

 

[Mkeller]

Alfi,

I removed the side cover from the injector pump and inspected the rack inside the pump.
It is moving freely, right and left without friction when moved by hand.
When the stop solenoid is activated the rack only moves about 1/8th of an inch to the left, still leaving a 1/4" of play.
I did remove the stop lever arm from its splined shaft and added a few degrees of rotation to gain a bit more of travel of the rack. After starting the engine again the stop button could almost shutdown the engine but by giving the stop solenoid a finger push it would work.
So my question is, how much movement of the rack is required to initiate shutdown?
Also I would like to know if anyone has an idea as to why my Simms injector pump would suddenly be out of adjustment. All external mechanical connection look correct.

Thanks,
Roger

You might try cleaning the solenoid. Both of mine were inoperable. Lots of rust dust interfering with operation. I Cleaned them with an electronics cleaner and lubed all moving parts. One now works perfect. The other is still too weak to function. I will replace it with a $25 Generic solenoid off Ebay.

 

[RFA]

First, apologies to Alfa Mike (not Alfi)

After much frustrating trial and error I finally had to drill new holes for the solenoid mounting bracket to get the required travel to initiate shutdown.
I still don't know how it got out of adjustment over the winter, those little boat gremlins perhaps?
Thanks
Roger

 

[Mischief]

You might want to check available voltage at the solenoid. The solenoids should never go out of adjustment. Sounds more like the solenoid is not traveling it's full stroke. Also check current draw of solenoid when activated, and check resistance. If windings are shorted together, they will have less magnetic field generated, and be weaker, not able to pull solenoid plunger to full stroke. You can remove to clean, and bench test operation. Test before and after cleaning, to verify difference.