broken inner spring hydraulic head

[marcel 01]

hi
the last time I started my m35 the engine went full trottle , I switched of with the engine stop and after that the engine would not start again. searching for the problem I dissambled the hydraulic head and found out that the plunger inner spring was broken. my question is this : did the Engine go full trottle because of the broken spring or did the spring break because the engine went full trottle and do I need to look for another problem in the fuel injection pump?

 

[rustystud]

The spring broke due to the full throttle. The springs function is to "pull" the plunger down against the cam roller. If the plunger is not held tight to the cam then it cannot build up fuel pressure. It would just "float" and do nothing. No pressure, no run.
The usual cause of a full throttle situation is the control sleave sticking on the shaft. That is usually caused by old fuel which gets "gummy" over time.

 

[FloridaAKM]

I bought a deuce from GP that had that HH problem, but the button was damaged also. Replacing the spring (good luck finding one) after inspecting the button for damage should put your truck back on the road. Good luck with your repairs.

 

[marcel 01]

ok thx rustystud and floridaAKM for the response .luckely I did find another old fuel injection pump whit the same p/n HH and used the spring from that one. where can I find the control valve?, couldnt find it in the t.m.(maybe I read over it)

 

[FloridaAKM]

"Control Valve" I'm not sure what you are referencing as a "control valve". Are you talking about the button on the head under the retainer? That should be in the HH head that you took apart to get the spring, or in your old head if it is not damaged.

 

[doghead]

I think he means the fuel shutoff valve in the HH.

 

[Squirt-Truck]

Fuel control sleeve

 

[Floridianson]

Fuel control assembly under the shut down cover on the side of the IP. You had to remove it to get the head out. Fuel control assembly stuck in the wide open position as said because tarnish on fuel control assembly shaft. Also you did not leave the engine cable shut down cable pulled out and locked when you left the truck. If you would have left it pulled out it would have been stuck in the shut down position and it would not have started. Then you would have just fixed / cleaned the fuel control assembly and it would have been working correct and you would not need to fix the Head or change your under ware.

 

[marcel 01]

ok, thx. the fuel control sleeve isnt sticky, when I turned the HH upside down and back the sleeve slides also up and down on the plunger. and when stopping the engine always pushing the engine stop back. I think I give everything a good check and reassemble the HH and try it again.

 

[rustystud]

"Control Valve" I'm not sure what you are referencing as a "control valve". Are you talking about the button on the head under the retainer? That should be in the HH head that you took apart to get the spring, or in your old head if it is not damaged.

I wrote "control valve" instead of "sleave" in my last post. I corrected it. My bad.

 

[Floridianson]

Plunger collar /sleeve Yes the plunger collar should float free and yes that is how you check it by turning the head up side down. The most common cause of wide open throttle is operator did not leave the shut down cable pulled out and left it pulled out when he was done with the truck. Now shut down cable not left pulled out plus sticking fuel control assembly the truck will go to wide open throttle.
The plunger collar can move free on the plunger and it still go to wide open throttle as said if fuel control assembly is sticking / stuck. Every one I have worked on it was the fuel control assembly.

 

[TGP (IL)]

My shut down control will not stay out.
So I cut a piece of small hose to length, then slit it lengthwise.
After stopping I hold the control out and slide the hose on.


Also protects the cable shaft from rusting while out.


Hopefully this will save me a headache.
Been doing that a long time.


Is it supposed to stay out on it's own?


Tom

 

[doghead]

Yes it is.

 

[FloridaAKM]

I have seen where guys have made a metal locking collar that goes over the cable shaft while it is pulled out. While this is locked out, no one can start the truck unless they know to disconnect the cable on the HH on the engine. Even better than locking the steering wheel as a theft deterrent.

 

[TGP (IL)]

Yes it is.

OK.
Any idea why it won't?
Bad cable control. something amiss under the cover?
Thanks
Tom

 

[rustystud]

OK.
Any idea why it won't?
Bad cable control. something amiss under the cover?
Thanks
Tom

If you look at the cable you will see what looks like grooves or teeth cut into the rod. They basically "ratchet" against the collar which is on the dash. What you normally have to do to "release" the rod is to give it a slight "twist" and then it slides back in. That is to release the "teeth" from the collar. What happens over time is the teeth get worn out and no longer catch. So if yours no longer holds that means you need a new pull/lock assembly.

 

[Floridianson]

The spring broke due to the full throttle.

The problem I have with that thought is it might not be the only way a spring can break. Lets take the case of Allen's truck. Here he had a broken spring but the fuel control assembly was working free and the plunger sleeve was not sticking on the plunger. I do not believe his truck ever went to full throttle. Replacing the spring and cleaning the delivery valve is all it took to have it running again.

Corrected post to read what I wanted to say.

 

[rustystud]

Well the problem I have with that theory is the case of Allen's truck. Here he had a broken spring but the fuel control assembly was working free and the plunger collar was not sticking on the plunger. I do not believe his truck ever went to full throttle. Replacing the spring and cleaning the delivery valve is all it took to have it running again.

If the spring is broken then what would hold the plunger down against the "Tappet" ? You do realize that spring is just like a valve spring on an engine head. If it is broken then it just flops around. Nothing there to "hold" it against the valve seat. Same thing here. That plunger spring is needed to "hold" that plunger against the Tappet which rides on the cam. Without it, it will just flop around in there never building up pressure. After all, why would it build pressure if it's not being pushed up and "forced" down by the spring. It would just stay up and never come back down. Really James, look at it.
Of course if the spring is broken at the top or very bottom, then there might be enough pressure to make it work half-ass. So your saying your head was half-ass ?
Oh, about the delivery valve needing cleaning. Glad I could help there leading you to the problem. Your welcome.

 

[Floridianson]

Ok I had to do like you do correct a post. Yes I know how and why the IP works. I am in Virginia and not on my computer and this can be disused when I returned next week. As far as your answer to the OP broken spring yea you were 100% correct. Wide open throttle broke his spring. As far as you having the correct answer on Allen's delivery valve problem you did say it could be the plunger also so here you had a 50/50 chance. We already had plans to check the delivery valve before you posted. But yea you guessed it. I already said it was my fault for not making Allen strip the head of everything and all ports to get a good cleaning. I just helped him take it out and put it back in as he took care of the rebuild. Not to derail this thread I will start another one on problems that happen to the IP system and broken bad parts.

 

[Floridianson]

hi
the last time I started my m35 the engine went full trottle , I switched of with the engine stop and after that the engine would not start again. searching for the problem I dissambled the hydraulic head and found out that the plunger inner spring was broken. my question is this : did the Engine go full trottle because of the broken spring or did the spring break because the engine went full trottle and do I need to look for another problem in the fuel injection pump?
View attachment 761555View attachment 761554

Sorry to derail your thread. If you could please let us know what you find that caused the wide open throttle and the problem that it caused. The wide open throttle problem has happened may times to others so don't feel to bad. I have always preached to leave the shut down cable pulled out. I have preached before you start a truck that has not run for a while or a truck that you don't know for sure the fuel control is working free is to take off the shut down cover and check. Then you can check the fuel control assembly for free movement.
Hope you can get the parts as easy as my friend. My friend had to go back and clean his delivery valve so that took us longer to get her running. You maybe should do the same thing that he had to do. Problem was he had to do it with the head already installed. That is taking out the overflow valve and the delivery valve and check /clean them.