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Discussion Starter #1
so im still in the process of bleeding fuel lines...:banghead:

i read the entire fuel article by joe g. but still no luck with this damn thing haha :doh:

as of right now i can get a good stream of fuel of out of both bleeders on top of the big fuel filter, and i can get the injection pump full. now the reason im scared is because i cant get any fuel out of the injection pump.

so tonight i took off the intake horn to get a good access point to the pump. i cracked all six lines off the pump, bled the air out at the fuel filter and had my wife crank the engine over while i hit the thumb primer and no fuel would come out of any them.

the last time the truck ran it had bad fuel lines but it ran like a top, but when i would slow down i had to put it in neutral and give it some throttle. but it started back up everytime. the last time it ran it sputtered pretty hard (in park) so i revved it up and she sputtered out on me, and now here i sit.

did the legedary p7100 fail on me? :confused013:

any help? pleasssse
 

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hey this might not help much and may infact be an insult, but i replaced my p-pump a while back and after putting it all back together i could not get the truck to fire.

Finally i came across my problem which was the connection on the inlet fuel line at the pump. on mine this is a metal line and it has a sort of rubber seal on it. i had this back together and tight but after i took it apart i disconnected the bracket that this line sits in and then put the line together and it slide in probably another half inch from where it was before and fixed my problem. after that i could get straight fuel at my injectors.

that line is also suction because it is before the pump, so if it isnt tight you may not see fuel which i didnt.

simple and probably not it but you might check it, good luck
 

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have the injector lines tight on the pump and loose on the injectors.... like finger tight, if that..... crank the engine over for 45 seconds or so, then crack each injector slowly, u should hear the air escaping as u crack them.... tighten them all up except #1 (front) put ur foot to the floor and crank, it should fire up and run rough, tighten #1 and let it idle for a bit....
 

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Discussion Starter #4
thanks fellas ill try that stuff tomorrow after work and then post back, im hoping its not the pump because im already way over budget on this truck and another 2 grand would'nt fly with the wife haha
 

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ya i just crack the lines at the injectors.
 

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make sure the shutoff solenoid is pulling up all the way (and make sure the pump shaft is actually turning when it does!)
 

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also i ment the lift pump im still confused... i thought the p-pump was the lift pump, but i think that is actually the injection pump?? dono :confused013:- not much of a mechanic and very new to the diesel world:stirpot:
 

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also i ment the lift pump im still confused... i thought the p-pump was the lift pump, but i think that is actually the injection pump?? dono - not much of a mechanic and very new to the diesel world
 

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:doh::banghead:


so what are u actually wanting to know ?:confused013:
 

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fuel basics

you suck fuel from the tank with the lift pump. the fuel lines are a and run up to a bracket on top of tranny wich is hidden behind the fuel filter.:S: The lines are braided steel and are probably frayed and use quick ( fn itch) pich connectors. one line is return and connects to the fuel return line under the p-7100, the other line transits from flex to hose and then to the rubber thingy ( washer) to the fuel heater, from the fuel heater it goes to the lift pump through the 90degree hose.:shock: Now the lift pump pushes fuel up through the fuel filter, then to the p7100, this is pressurized fuel and as long as you have good lines from the fuel tank to the p7100 you will positively feed it.:stirpot: However, if you have collapsed or frayed lines like i did, you will have problems. My truck sat for 7 weeks as i rebuilt all the accesories, fuel lines etc, and I simply primed my lift pump about 50 times waiting on fuel to fill new filter, fuel heater, hoses, etc.:thumbsup: when fuel spilled out of new filter, i tightened it up and primed it another 20 strokes, ensuring prsurization. When i finally started it 2 weeks later, it started after the third 20 seconds of cranking. I did not bleed any lines at injectors. I believe ( not positive) that they are self bleeding injectors, thats why they have the small line returning to the fuel filter. I think the excess fuel returns to the p pump.:blues:

So, if you have a NO Start, your solenoid is probably not lifting up and allowing the rack in the p7100 to travel, IE fuel is cut. No Fuel = No Start. Diesel is actually simpler than gas as t/s involves ONLY Fuel. Fuel supply controls power output as there is no throttle plate to control air. Fuel controls ignition event as ther is no spark to time. Fuel contols engine start and stop other than starter circuit through the fuel shutoff solenoid.:rof
 
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Discussion Starter #11
my celenoid is junk but i have it completely unhooked (has been since i bought the truck) the lever is up, is it possible to clog the p7100?
 

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Sorry if I missed something, but did you replace fuel lines? Mine did the same thing and I ended up replacing overflow valve, took out pre heater, and finally replaced my return line, and please take Joe G.'s advice and just get enough rubber line to run from inj. pump back to tank, it is so much easier that way. Anyway now mine fires up like new, no more throttle to the floor after it fires, no more having to put it in neutral when I stop either. Hope you get it going!!!
 

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grndodge,
yes i did replace all the the lines (supply and return from the tank) i got it running tonight by running a line from a gallon jug with diesel in it to the lift pump, bled the air at the injectors and she took right off.

if i take out the fuel heater will the pre-filter screw back in?
 

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Yep if I remember correctly there is an adapter that attaches it to the bowl just leave that adapter out and the pre filter bowl will bolt right back up. Ithink joe G.'s artticle gives a lot better instructions, but thats it in a nutshell, be sure to clean the pre filter screen while you are in there and make sure the gaskets are in good shape. Glad you got it goin.
 

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well i have good news, i was certain that i had a bad pump because i just replaced it, thought it was bum pump. anyhow after reading all your advice i decided to check some things, redneck style.

i dont have much tools with me here so i took that pump off and took it apart it seemed fine, and as many of you have said they rerley go out and i can see why there isnt much to them to go out. anyhow once i had that pump off i tried to siphion fuel through the feed line and was able to with out much effort, so it elimated the tank and any lines up until that pump.

i reattached the pump just above the motor with the feed line on and it primed and pumped fuel so i then took a look at that heater. i had read you have to drill out rivets to get it off but mine just has a inner bolt that holds it on and then the strainer goes in to that.

i removed that piece of crap (should off the first time) i checked all my connections and put the pump on and the truck runs great, so here is where i must admit stupididy, the first time i replaced that pump many of you said it probably wasnt the pump and i think you were right.

my wife had taken the truck in on student days at wyotech when she first started and had cleaned the pre filter/strainer and it was shortly after that my problems started, i think breaking all that lose started the problem and when i replaced my pump everything got tightened up good on that heater up until now.

so i should of listened:doh: i didnt remove that heater because i figured the designers put that there for a reason:rof anyways its in the trash now and my problems solved:thumbsup:

thanks for all your help:thumbsup: should of listened:spank: the first time couldnt have done it with out all of you:blues:
 

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they did put it there for a reason.... but think about it....

how much fuel is between the heater, and the injectors... all those fuel lines, ur fuel filter, the IP.... it was a nice thought, but really... on a cold morning.... your grid heaters are doing all the work.... the fuel heater is just wasting precious battery power...
 
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