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Discussion Starter #1
So my dad has a 90 7.3 IDI. He recently replacement the injection pump with a new one. Well ever since he did that the truck will not shut off when you turn off the key. You have to put it in 4th and kill the engine. We've messed around with the wiring and timing on the pump and nothing is helping. Any thoughts?
 

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So my dad has a 90 7.3 IDI. He recently replacement the injection pump with a new one. Well ever since he did that the truck will not shut off when you turn off the key. You have to put it in 4th and kill the engine. We've messed around with the wiring and timing on the pump and nothing is helping. Any thoughts?
So, when you turn your key off in the truck, it sends an electrical signal to the injection pump telling it to stop pumping. So you have one of a few issues. Your ignition switch is bad, there is a interruption from the ignition switch to the pump, or the pump itself has a defect. All these pumps are rebuilt so its possible it may have a defect that was never fixed during the rebuild. I would look into the ignition switch, they are easy and cheap to replace, if thats not it i would check the wiring for the turn-off portion. If all that looks good, it only leaves one thing, the pump. Hopes this helps!
 

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I imagine its the wiring going from the ignition to pump. It's just weird how it starts and runs normal but won't shut off. The truck didn't run for a couple years and mice tore the wiring to s***. Example: high beams don't shut off, theres no more radio wiring harness, etc. Since we switched all the wires around several time we figured it was either completely gelled and jelly-like fuel (which was found in both tanks) got into the pump, or the wiring. Just going to live with the issue. Thanks for the reply.
 

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That's something I need to check.. It has to be wiring. When it warms up I'm going to work on it more and probably run all new wires to it. Thanks for the reply man
 

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There are two plugs that go into the injection pump on the right facing the engine compartment. One of them (I think the back one) goes to the fuel solenoid. That's the one that when energized lets the engine run. When you turn the key off, the power is cut and a spring retracts it and the mechanical link reduces fueling to zero. If you pull the plug and it continues to run, the solenoid is stuck ($100 part I think). If it dies when you pull the plug, it's probably a bad ignition switch, which is common, cheap and easy to fix.
 

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Discussion Starter #9
Thanks for the input, that will be the first thing I check since its the cheapest. This truck was an Ameren dump truck and only has 30,000 original miles so it is a gem. It just sucks that freakin mice are chewing everything out.
 

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My money is on this fix.

There are two plugs that go into the injection pump on the right facing the engine compartment. One of them (I think the back one) goes to the fuel solenoid. That's the one that when energized lets the engine run. When you turn the key off, the power is cut and a spring retracts it and the mechanical link reduces fueling to zero. If you pull the plug and it continues to run, the solenoid is stuck ($100 part I think). If it dies when you pull the plug, it's probably a bad ignition switch, which is common, cheap and easy to fix.
I had this same issue only it shut of going down the road and would not start. Once I replaced the shut of solenoid everything was fine. Just be very careful when you replace it because it is in the governor system. You might want to start it the first time with the air cleaner off and a board ready to cover it to stop it in case you get the solenoid in wrong because it may want to "run-a-way" and the only way to stop/shut it down is to smother it by blocking off the air to the engine.

Good luck sorry I can't seem to find the video I had showing just how to replace it.
 

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Im glad you posted this. Dad finished the wiring yesterday and he called me and said it didnt make a difference. Ill call him and tell him its the shut off solenoid. Ill just look up where it is. Thanks man and yeah ill tell him to have a board or something handy in case it runs away

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Im glad you posted this. Dad finished the wiring yesterday and he called me and said it didnt make a difference. Ill call him and tell him its the shut off solenoid. Ill just look up where it is. Thanks man and yeah ill tell him to have a board or something handy in case it runs away

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In case you or anyone else is wondering. Mine stopped on the road because it went bad in the extended position. I wired it in the retracted position to get it started and get it home. So I surmise yours might have went bad in the retracted position. You can test it once you take it out by just putting power to it and see if it extends and contracts. It should contract with power and extend without power. Thus when power is pulled it extended via a spring inside and shuts of the fuel. Put power to it, it retracts to open the fuel.
 

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Discussion Starter #13
Just for reference the shut off solenoid was the reason. We replaced it earlier today and now it shuts off like normal. Thank you totalloser and Debreke for this, we wouldve dumped a lot of time into useless wiring.

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Glad you got it worked out. I guess you found that I was pointing to the wrong solenoid. :)

I think the only hitch in replacement is that the kill solenoid must be removed to replace the cold start solenoid, and that the kill solenoid looks like the hook part is supposed to go around the lever- it's not. It's only a "push" lever. I just replaced a bad CS solenoid on my buddy's truck yesterday and got a more recent look at it.
 
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