7.3 dies at full throttle

Cheesy

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Howdy. I need a little bit of help here. Hope y’all have some suggestions as to what this might be. To start I recently got my injection pump rebuilt. Just got it put back in and took it for a drive last Saturday. Drove it around a little while. And after I had drivin for a few miles and everything seemed fine I got on a flat stretch and floored it to see what it would do. Got it up to about 3300 rpm and it just flat out died. And would not start back. So I start lookin to make sure I’m getting fuel. Lift pump is pumping it real good into the injection pump. But when I turn it over no fuel is coming out of my injection lines themselves. It’s just getting pushed through the return lines. My shut off sylinoid is workin far as I know. I can hear it click like it aught to. Anyway. Got her back runnin. Drove her for a cupple more days ran great. Then floored it again yesterday and same thing happened. Gets about 3300 or so and it dies. If my lift pump is pumpin good fuel. And my shut off sylinoid is open What could be keeping my injection pump from pumping? It was rebuilt by a reputable local guy that I trust. And when it runs it runs better than ever except for that. My truck threw a code saying my throttle position sensor was not calibrated correctly. Could this effect it. Could it be that the even though my lift pump is pumpin a lot of fuel just sittin that when I get it under load like that it quits? Don’t think it’s air. Just put on RnD return rails. No fuel seepage so I’m kinda doubtful that it’s air intrusion. Any body else run into a similar problem?
 

Austin86250

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any white smoke indicating air? perhaps its a sticky metering rod in the injection pump try some atf or your preferred additive. i wouldn't completely rule out shut off solenoid yet perhaps there is a loose connection and flooring it rattles it loose
 

Cheesy

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No white smoke Some more info. After doing nothing to it but letting it sit for a day it starts up. So after it dies it won’t start fuel goes into pump but does not come out injection lines. After just sitting it will pump and start up and run seemingly flawless
 

IDIBRONCO

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First, air intrusion is when air gets drawn into your fuel system while the engine is running. You can't get air intrusion from the return caps, lines, or your rails. That is all after the injectors and can't let air get into your fuel system while the engine is running. Second, I recommend calling the rebuilder and getting him to give you suggestions as what to do. If this wasn't happening before the rebuild, then it's the responsibility of the rebuilder to sort this out. That's not to say that you shouldn't ask here, but your first move should be to call the rebuilder. If you buy a new car and it's not performing right, you take it back to the dealer. This is the same thing, just with different objects.
 

IDIBRONCO

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If you buy a new car and it's not performing right, you take it back to the dealer.
Of course I say this and then do a little bit of remembering. While I was working at the Good Year store, I lost track of how many new vehicles came through to get four new tires and an alignment with 12,000-15,000 miles. One had less than 8000 miles. It was all types of vehicles, not just one or two brands. I must not think like most people do these days. If it was me, I'd be taking that vehicle right back to the dealer and telling them to FIX IT! It has a warranty for a reason! I'd even threaten to drive that vehicle up someplace that it couldn't possibly fix if it didn't get taken care of. The way I see it is that if I spent the money for a new vehicle (injector pump in this case) and it's not right WHILE it's still in warranty, then I shouldn't have to pay to get it fixed.
 

Cheesy

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I’ll give a call tomorrow. If it’s the pump I have no doubts he’ll make it right. Just was weird to me that a fresh rebuild would do that. Also strange how after sitting for a spell it will work no problem. But I’m not familiar with the inner workings of the pump.
 

IDIBRONCO

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Me neither but I feel that's the best thing to do. I'm not blaming the guy for anything. He's human and sometimes thing just happen. Years ago, we put three engines, two sets of injectors, and a few individual injectors in a truck because we had installed a complete rebuilt (overhauled not remanned) engine and it had a knock. Finally, we replaced the IP and the knock went away. It was sent back to the rebuilder and he fixed it. He wouldn't say what happened, but he made it right. A complete engine was one that was ready to install complete with the fuel system.
 

IDIDIDIhoDhoDhoDO

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If you leave it in park so you can rev it to 3300 rpm with only partial throttle does it still stall out or does it need to be floored? My guess is a problem with housing pressure inside the pump, or possibly some funny business going on with the governor inside the injection pump.

Inside the pump, the housing pressure is controlled by both an internal calibrated vent wire and a ball and spring regulator fuel return valve (you can see the return valve screwed into the top of the injection pump, it has the fuel return line come off of it). If the housing pressure inside the injection pump gets too high it will shut down the pump's injection event.

I wonder if the fuel return valve is sticking and making the IP housing pressure too high and shutting down the pump, then that pressure bleeds down over time and allows the pump to function again several hours later.

Let us know what you find.

EDIT: I just checked on mine and that return valve on the top of the pump is just a fitting and not a ball and spring valve. I thought it had a ball and spring as a check valve but it does not. The principle is still the same though, if that return fitting gets blocked in some way and allows pump housing pressure to get too high, it shuts down the injection pump.
 
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Cheesy

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After it starting back up yesterday I tried to recreate the situation near (near my house so I wouldn’t need a tow haha) to no avail. Seemed to run fine no issues Still gunna call and get some ideas here in a few minutes. Cause what your describing sounds like it would make sense. First time it happened I was in 3 gear 3300. Second time was over drive probably 2800. Both times pretty much petal to the floor. I’ll see what I can’t find out
 

Black dawg

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Many years ago I installed a used pump that I bought. Truck started and acted normal. Drove for a bit and at speed the engine suddenly quit. No fuel to injector, but fuel pressure to pump. After sitting for a couple hours, started up and drove normal until it did it again. found a piece of stuff blocking the vent wire (acts just like blocked return line). Cleaned it out and used that pump for many years.
 

Cheesy

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Many years ago I installed a used pump that I bought. Truck started and acted normal. Drove for a bit and at speed the engine suddenly quit. No fuel to injector, but fuel pressure to pump. After sitting for a couple hours, started up and drove normal until it did it again. found a piece of stuff blocking the vent wire (acts just like blocked return line). Cleaned it out and used that pump for many years.
After talking to the guy I’m thinking the exact same thing What I hadn’t thaught about is the new return rails I put on I really greased em up good so as not to ruin the new O rings. But I’m thinking that grease has clogged the lines and when it gets under that pressure it kills the pump and then bleeds off over time. Or I have another clog. I’ll try an isolate the clog later
 

Cheesy

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Could be that it’s worked itself through now too. Since I’ve run it for a while and it seems like it’s good
 

Cheesy

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Just an update. I took the return line off the ip and blew through it with my mouth. Seemed real hard at first but with continued blowing it was easy. I believe I read some where recently in a previous thread on how to diognose where a clog could be in the line but can’t find the thread. Anybody have protocol for doing this?
 

IDIBRONCO

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I'm not going to say that this isn't your problem, but if there was still some fuel in that line, I would have given some resistance until it was cleared out. Just food for thought.
 

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