Archived 96 12v wont start

[EBottema]

Hey guys



Drove my truck 100 miles today and then about 6 hours later i got in it to start it up but it cranks and doesnt start. When i get home in an hour im going to add fuel since i was low. hopefully im just out of it... What else could be the problem? Lift pump?? how much do they cost? Ive had any diesel fuel system experiance so please give me instructions on what i should do in the morning to start checking into the problem...

Thanks!



Erik

 

[Forrest Nearing]

even with a bad lift pump it should still start up or at least try to start...



put some fuel in it, crack a few injector lines, crank for 5-10 sec, let it cool for 20-30sec, repeat, etc. and look for fuel. if no fuel, check the fuel shutoff solenoid (might go ahead and check that first)



you might also check the rubber lines to/from the pump. if they're old you might want to replace them as they'll draw in air.



Forrest

 

[EBottema]

Just put about 4 gallons of fuel in the tank and tried to start it... Still cranking and no starting



Anyways, i will do what you said, do i crack the injection lines off the pump or off the injectors?



Also, how do you check the fuel shutoff solenoid?



erik

 

[Got Smoke?]

make sure the fuel shutoff solenoid is coming up when you hit the key.



If its not its one of two things.



1) Relay on the firewall

2) Blue fuseable link on the D-side battery.

 

[Joe G.]

You don't have to crack injection lines on a 12 valve. If you have fuel to the pump with enough pressure it will start. In addition to what Mark suggests, you should check for an air leak. The lift pump is pretty reliable. Air leaks and bad overflow valves have caused a lot of lift pumps to be replaced that were really ok.



If the fuel solenoid is working correctly, loosen the bleed screw on the output side of the fuel filter. Then prime it with the push button on the lift pump. Watch for bubble in the fuel at the bleed screw. If you can't get rid of the bubbles with the push button then you probably have an air leak.

 

[JoshPeters]

The solonoid they are talking about is on the drivers side of the injection pump. standing there you will see a cylinder with a rod going towards the bottom of the injeciton pump. Turn the key on, lift up on that rod(towards the top of the pump) and try to start. I've had mine stick a few times.



Josh

 

[EBottema]

UPDATE:



As Josh and the rest said, I turned the key on and pushed up of the Fuel solenoid rod and it locked into the upper position. Tried to start it and still doesnt start... . Whats next



If anyone can give me detailed instructions/pictures since this is my first time id appricate it





thanks

erik

 

[Joe G.]

Originally posted by Joe G.

If the fuel solenoid is working correctly, loosen the bleed screw on the output side of the fuel filter. Then prime it with the push button on the lift pump. Watch for bubble in the fuel at the bleed screw. If you can't get rid of the bubbles with the push button then you probably have an air leak.

Did you try that?

 

[EBottema]

I'm gonna try that right now but i have to figure out where the prime button is and the output screw..... any pics anyone have?



erik

 

[EBottema]

UPDATE #2:



Just cracked the output fuel screw and pushed the prime button about 25 times and i kept getting small air bubbles. Now what?



i also noticed some amount of fuel dripping on top of the starter (specifically the cable) when i had the fuel cracked and pushing the prime button. I dont know if anything has to do with that. .

 

[Joe G.]

The next thing to try is to remove the fuel heater. It's the black plastic thing that looks like a hockey puck in the fuel heater/pre-filter assembly. You need a 17mm socket and an 8mm allen wrench. Remove the pre-filter from the bottom of the assembly with the 17mm socket. Be careful of the gasket. Then remove the fuel heater by using the 8mm allen wrench on the shiny screw that holds the fuel heater in place. You will need to remove the wiring harness that is attached to the fuel heater. Also remove the gasket. It is the same as the gasket that is used for the pre-heater. The pre-heater will fit where the fuel heater was. Use one of the gaskets. Make sure that the connector for the input line to the fuel heater/pre-filter assembly is ok. It may be leaking some air. The most common air leak is the electrical connection on the fuel heater. After putting it back together without the fuel heater, prime the system with the push button and try to start. It may take more than 25 pushes to prime it.

 

[EBottema]

The thing is being a PITA right now. I pulled the fuel pre filter off and everything looks fine, small amount of crud but i cleaned it. I dont see how im gonna get the pre heater off... do i need to remove that, do you do it from the top or bottom? where is the allen screw located at? Sorry guys bear with me. i think i should replace all the rubber lines since it might be causing a leak since they look original on a 160k mile truck. can anyone tell me what i need before i go down to the truck center to get a new fuel filter also... . erik

 

[Joe G.]

Hang on a few minutes and I will have some pictures of the screw and fuel heater put in my album so I can post them.

 

[Joe G.]

For some reason I can't get into Reader's Rigs right now. Look at the bottom of the fuel heater with the pre-filter removed. There is a large round shiny screw in the bottom of it that the pre-filter screws into. Stick an 8mm allen wrench in the hole in the center. It is an 8mm hole clear thru the screw.

 

[Joe G.]

I finally figured out what was wrong with accessing Reader's Rigs.



The first picture is from the service manual and shows the fuel heater. Note the large screw thru the heater element.



#ad




The next two pictures are the screw that holds the fuel heater in the assembly. Note the hex shaped hole in the end view.



#ad




#ad

 

[EBottema]

Okay, thanks a bunch... . I just changed the fuel filter (was not so bad only took 30 minutes or so) Tomorrow i'm gonna pull the heater out. What leaks on it and what is the reason for pulling it out? To replace it?



Let me know

erik

 

[Joe G.]

The fuel heater overheats for some reason, probably a bad fuel heater relay. I haven't looked into it yet. The overheating causes a crack in the electrical connector so it leaks.



The reason for removing it is to test. The shiny screw is just an adapter to allow the fuel heater to be placed between the fuel input and the pre-filter. If you remove the heater, the adapter screw, and the gasket above it the pre-filter will bolt right up the top assembly. The truck will run fine without it. You can probably remove it permanently since you live in Glendale. So if you remove it and the truck runs fine without it then it probably leaks. Remember to check the fuel input fitting. It can leak too.



I have some pictures around here somewhere (??) that show the fuel heater/pre-filter assembly with and without the fuel heater. If I can find them I will post them.



I like to find what the problem really is before I fix it instead of throwing expensive parts at it until the problem goes away.

 

[EBottema]

Okay i will do this tomorrow morning. I prob will not need it for now so i will remove it and see what happens... How should i check the fuel inlet fitting? Is it on the top on the fuel pre filter housing?



I know i have heard about the rubber fuel hoses leaking but its hard to believe that could be the problem. Should i replace all of them? Does anyone have a list of what i need? Thanks for your help Joe! Hope it all works out before the weekend



Erik

 

[bighammer]

I would guess that pushing the primer button with bleeder on top of filter housing open would get fuel coming out with each push. (making a mess) Does it sound like air going back in after each push? (like each push sends a bit of fuel and bubbles out, then it sort of sucks back in?)



My truck worked until I replaced the fuel filter one day. Then there was NO WAY to re-prime. I could feel the primer moving fuel, but the open bleeder did as described above. I finally got a new left pump and found it had a bad check valve. The fuel was just going back & forth in there.

 

[Joe G.]

The inlet fitting to the fuel heater/pre-filter assembly is kind of different. Just make sure that it is tight and there is no wiggle in the steel line. There is some sort of soft washer in it that gets kind of ratty and can leak.



The fuel supply hose can get bad and leak air.



The lift pump can fail because of bad check valves but that is pretty rare. It has three O-rings in it that can get bad and leak. Cheap to replace those. The O-ring the fails most often is the one for the push button. It's easy to replace with the pump on the engine.



I don't know where to get the check valves if there is a bad one.