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Discussion Starter #1
i bought this used truck.. previous owner said it needs a new pcm to run.. got a used one but no much happens... the dash turns on , wait to start, oil light... no crank from ignition but i can get the motor to turn over from starter solenoid. what should i check? batterys are at 12.2 volts.. i got power to starter solenoid and glow plug solenoid.. im new to diesel motors
 

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Welcome! We'll need some more information. Year, Auto or Manual trans, any modifications that you know of, any other recent work? Do you know if you got a correct used PCM for your particular truck? Cheers!
 

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It should be good. My truck is a 96 with a manual and the PCM is a ALF4.

Have you checked the neutral safety switch on the clutch?

Are you getting any smoke out of the tailpipe when the engine is turning over?

On the top of the high pressure oil pump on the top front of the engine is a plug that you can remove with a allen key. Take it out and see what the oil level is in it. It should be within 1/2" of the top. If it is low fill it with the same oil that you put into the engine. Then try to start.
 
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Discussion Starter #7
It should be good. My truck is a 96 with a manual and the PCM is a ALF4.

Have you checked the neutral safety switch on the clutch?

Are you getting any smoke out of the tailpipe when the engine is turning over?

On the top of the high pressure oil pump on the top front of the engine is a plug that you can remove with a allen key. Take it out and see what the oil level is in it. It should be within 1/2" of the top. If it is low fill it with the same oil that you put into the engine. Then try to start.
No I didn’t see any smoke in tailpipe.. I’ve only had tried jumping the starter solenoid... I noticed no fuel in the filter bowl... I’ll check the neutral safety switch
 

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Kind of along the same lines as bugman was going, if you clutch pedal/linkage has an excessive amount of play (which is common on these trucks), the clutch pedal switch won't close when the pedal is pushed in causing a no-crank situation. Check the bushing where the clutch master cylinder rod attaches to the pedal. If there is a lot of play there, it could be your problem (at least with the no-crank). Cheers!
 

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On the fuel bowl, this engine has a mechanical two stage fuel pump. It draws fuel from the tanks on the low pressure side and sends it through the filter, then back to the fuel pump high pressure side and then to the injectors. The unused fuel then returns to the filter housing where it goes through the fuel pressure regulator before returning to the tank that it was drawn from. Providing that everything is working properly.

So no fuel in the filter housing could mean a number of things. No fuel in the tank it is drawing from, a blocked fuel line, bad pickup tube and or foot in the fuel tank, or a bad fuel pump.

I know that you said that you have voltage to the glow plug relay, is that to just to one large lug or both, and do you have voltage to the small terminals.

Check for voltage in the under hood fuse box. Mainly fuse #22 and #9.
 

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Discussion Starter #10
Kind of along the same lines as bugman was going, if you clutch pedal/linkage has an excessive amount of play (which is common on these trucks), the clutch pedal switch won't close when the pedal is pushed in causing a no-crank situation. Check the bushing where the clutch master cylinder rod attaches to the pedal. If there is a lot of play there, it could be your problem (at least with the no-crank). Cheers!
So I looked and found that the pedal is hooked with a wire instead of a clip.. has some play.. you think I should buy a clutch switch? Will need to buy the clip and maybe the plastic grommet
 

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I've never really heard of problems with the switch itself. It's mostly the excess play causing it not to function. Normally the clutch master rod is held on the linkage only by the infamous bushing (no clip). Some folks will do the "Heim Joint Fix" if the rod hole has been damaged, while some others have trimmed the bushing and used a "drill stop/shaft collar" to keep the rod from popping off. Cheers!
 

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Discussion Starter #12
I've never really heard of problems with the switch itself. It's mostly the excess play causing it not to function. Normally the clutch master rod is held on the linkage only by the infamous bushing (no clip). Some folks will do the "Heim Joint Fix" if the rod hole has been damaged, while some others have trimmed the bushing and used a "drill stop/shaft collar" to keep the rod from popping off. Cheers!
I order a bushing and a clutch switch.. I wanna try and hook up a fuel line inlet side to a jug of diesel.. just to see if it would start... is it ok to fill the filter bowl with fuel? Mine is empty.. I can see wetness in the bottom of the bowl
 

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You can fill the bowl, but have the filter in there when you add fuel (you will have a mess if you try to insert the filter after filling the bowl). Cheers!
 

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Discussion Starter #14
You can fill the bowl, but have the filter in there when you add fuel (you will have a mess if you try to insert the filter after filling the bowl). Cheers!
Thanks for advice!! I plan on hooking a fuel line into the inlet side of the fuel pump to a jug of diesel to see if it would pump that and fire up my truck.. waiting on my clutch switch and bushing in the mail.
 

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Discussion Starter #17
I got someone to diagnose my truck.. he hooked a scanner up.. he says there is no oil pressure.. it may be hpop or lpop.. the oil pan is dented and my have a bent oil pick up tube.. we may pull the motor.. just wondering what you guys think I should do
 

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If the pan is dented enough, the pickup tube could have cracked causing it to ingest air and not pickup oil. You may want to put a mechanical oil pressure gauge on it to see what LP oil pressure is doing. Cheers!
 

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Discussion Starter #19
If the pan is dented enough, the pickup tube could have cracked causing it to ingest air and not pickup oil. You may want to put a mechanical oil pressure gauge on it to see what LP oil pressure is doing. Cheers!
I had someone hook up a scanner he said there was no oil pressure in either hpop or lpop
 

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Just a note: A scanner can tell you HP oil system pressure (or lack of), but the PCM does not monitor the LP oil system. The dash gauge is really only a glorified idiot light as it uses a pressure switch instead of an actual sending unit. Cheers!
 
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