My L29 Laundry List

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John B

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If you go from step 10 on, it mentions that the fuel pump should still run at operating temperature and in nominal oil pressure even if the fuel pump relay is removed... It even states in another section of the book that the VCM controls the fuel pump and takes input from the key switch, relay and oil pressure switch to power the fuel pump, and apparently those systems are redundant to each other.

That could very well be correct. Could be a safety thing when the truck is underway. When I remove/replace my fuel filters, I pull the relay to relieve pressure. It kills the engine..BUT I have only done this to engines that were cold and not warmed up.
 

Black_cirrus

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I've pulled the relay on a couple s-10s and they will run, had one I was troubleshooting and unhooked both sensor and relay and it struggled for 10 seconds before I shut it down.
I've done the relay on a tbi truck and it ran.

More on topic I saw one fuel pump that the hose was pinched on the sender. Shouldn't be your problem but, food for thought.

I was told at a class the redundant fuel pump system came from a car stalling on a draw bridge and the person dieing.
 

Tom P

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You're probably correct that it's some sort of a safety issue. Perhaps it is a vehicle in motion deal. Where's Skylark at? This seems like something he would know the answer to... haha
 

someotherguy

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*ahem*

Rearmost bolts were left threaded in just enough to keep the bed from sliding off. That ugly buckle in the side was from a goosneck accident by previous owner...not my shady fuel pump replacement job :)

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Richard
 

someotherguy

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And for what it's worth on the fuel pump relay, I've not had any that would continue to run with the relay pulled. I've not studied the issue enough to make a determination on exactly why; it may be that the redundant oil pressure sending unit circuit will keep it running if the relay fails - but is still in circuit. Pulling the relay completely out may be defeating the circuit entirely. I've seen similar behavior with cooked relay/relay socket - once it quits making proper contact, fuel pump slows and stops. The pump on my '98 crew cab 7.4 was so loud I could literally hear the pump slowing down and the engine would begin stumbling.

Richard
 

Tom P

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I was able to drop the tank part of the way to access the top, and once I figured out the logistics of it, doing it a second time would be a breeze. If I'm pulling the bed off, Its gonna come all of the way off and I'll be doing new leaf spring mounts and rust mitigation while I'm at it. Some of the metal under my truck is now layered like pie crust. I wont be able to go much longer, safely. Had I known some of it was as bad as It was, I probably shouldn't have done my 400 mile camping trips. I should have taken some pictures to show, but I always leave my phone on the bench and get a little one track minded when I'm underneath the truck and crap is falling on me.
 

John B

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Yes, on Sunday, I did pull the relay after I came home when the engine was fully warmed up. It killed the engine in less than a minute.
 
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