Engine/Transmission (1994 - 1998) 1994 12V Need Help

[Twisted Shifter]

First let me say Hello to all ... I am new to TDR but not a toatal noob at diesels ... I have owned a 24V for a while but I just bought my first 12 v and its like starting all over again I will paste a few threads that I posted on another site to speed things up a bit... .....



Quick history …. I just bought a 1994 12v with 84,000 miles. When I picked it up I drove it for about 2-3 miles and it started acting rally rough. I managed to get it home but it would die if I didn’t have my foot in it. l



The idle was/is at 500 rpm so I tried to stretch the spring in the overflow banjo… no help. While I was tinkering with it the Water in Fuel light came on so I drained the fuel from the bottom of the fuel filter and all seemed to be well ……. .



I took it out tonight and went for a ride … (it was prob 20 degrees cooler tonight than it was Saturday) after the truck got up to operating temp it started running rough again and then it wouldn’t run unless I had my foot halfway to the floor and my foot on the brake to control speed.



Thinking it might be water again I drained more fuel … negative results.



I can get it to start if I hold the fuel pedal at ¾ throttle and it will run at 2k rpm for about 10 seconds and then start loosing power until it dies.



Thoughts comments?



BTW the fuel has a very DIFFERENT when its burning than my 2003 24v and lots of white smoke.





05/04/2005



Well I went in the rain and cleaned the Prescreen out …… I did not find what I thought I would …… very little junk at all but some junk non the less. I cleaned the filter with starter fluid rinsed with clean fuel and put it back together.



As before the truck ran but ran sluggish. The one thing that I can say is common between all three times that the truck has died on me is that it does the “staling” “dieing” what ever you want to call it after it has been run for a while and up to operating temp then shut off and restarted with in 20-30 min.



The white smoke drops drastically after the truck is up to full operating temp, but still pretty heavy smoke.

 

[WDimig]

im not expert but it sounds as if you have either a timing problem, or something is wrong internally with the pump.



wes

 

[Twisted Shifter]

I am pretty sure that I have a timing issue ... . that will be fixed by the stupid pump... . will that keep it from continuing to run at idle afer its warm?

 

[Forrest Nearing]

why not just bump the timing on the current pump? just to see if that's the problem...



a good used pump is worth more than one that's just considered a "core"

 

[Twisted Shifter]

I will try to adjust it if I get time ... This pump is going to Piers to be converted into a race pump.

 

[Smokin Ram]

Aside from the timing, check the fuel heater electrical prongs(the black puck above the fuel bowl), i had a 98 and own a 94, both and i mean both have experienced this problem, took me a week tro figure it out, going through all the fuel system, it ended up that the prongs had heated and melted teh plastic and was sucking air, it experienced the same "dieing" as more air was getting it. The white smoke sounds like timing, also check the fuel tank level sender unit, on the 94's the lines are steal, ive seen them rust out and suck air, also check your lines inside the fuel tank, the ones that spiral down (black) i had a sender unit fixed, and it worked great when the tank was above half, but below that the lines had cracks and sucked air. I know this may be off, but i had the same symptoms and did it ever frustrate me, spending all the time to find it. Hope this helps. You mentioned stretching the over flowspring, be careful with that, its sensetive, to adjust the throtle, its on the back of the pump, its a set screw it should run at 850rpm according to cummins. that 500rpm definately wont be helping.

 

[Twisted Shifter]

I have an electrical issue also ... . I noticed that the lights would flicker when I would hit the fuel pedal hard ..... now the radio works when it wants to

 

[Kirwin]

Have you changed the fuel filter?

First things first. Start with the simple things. Clogged fuel filter can do this. Possible fuel restriction on the suction side of the lift pump. Does the fuel pump solenoid pull up properly when the starter engages? Does it remain in the full up position? Is the lift pump putting out required pressure/volume? Why did you go right to the overflow valve? What were your indications that you had a problem there? Any chance that you can install a temporary fuel pressure gage on the fuel filter to see what you are running? This is where I would start. Ken Irwin

 

[Twisted Shifter]

Yea I am going to pick up a gauge I can put in line to test PSI. I went to the overflow on a hunch from another post .....



Fuel Filter is new, I cleaned the prescreen so I will check PSI

 

[Twisted Shifter]

Update but not much new …….



Ok I have confirmed that it only does this when its at operating temp. The white smoke all but goes away at operating temp (forgive me on my stupidity about the white smoke, never owned a 12v before)



I ran the truck for a long time after it was up to operating temp and it ran fine other than a slight lobe at idle, this would go away if I barley touched the pedal. I shut the truck off and tried to restart it and bingo it wouldn’t stay running. The idle is only at 400-500 in gear with the AC on so I would assume the idle needs to be turned up, but I couldn’t find the screw before I lost light outside.



I have checked all the fuel lines I can find none look to bee cracked.

I have replaced the fuel filter and cleaned the pre screen.



I have not checked the pressure ( need to find a gauge)

I could not figure out exactly what the Pre-heater was so I will look at it closer Saturday.





Thanks again to everyone that has helped me out so far.



Twisted.

 

[dieselworld]

The idle screw is very hard to see, you have to just feel the stop that the linkage rest on. My 12v was stalling out and running rough because of the low idle. I think a 10 or 11mm wrench is the size for the screw.

 

[wcjp]

The fuel lines can dryrot. They look ok, don't leak fuel but suck air. If the fuel lines are original they may need to be replaced. In addition to the supply/return don't forget the liftpump softline.

 

[Twisted Shifter]

I thank everyone for the help ...



I spoke with the shop thats going to build the race pump and they are positvie that the timing has slipped and thats the problem. So with that info the rebuild begins.....



I will remove the head and pump and prep them for shipping to the machine shop.



I will keep everyone updated as we go.



Thanks again.



Twisted

 

[Twisted Shifter]

Well I think I might have got her licked ... . bumped the idle up to about 850 running and 700 with AC on in gear. It seems to have fixed the not wanting to run issue. But the timing is way out.

 

[Twisted Shifter]

I know we have all scratched our heads on this but I ask that everyone do this one more time please.



The issue with the 94 and not wanting to run once its warm, I have some more info lets see if this helps.



I thought that the idle fixed the issue but it didn’t. It still does it if you run it longer than 5 miles.



Something that I noticed is that the fuel gauge starts moving erratically and goes closer and closer to Empty. I thought that it was simple an issue of the timing being out and I was using large amounts of fuel but that’s not the case because if you let the truck sit overnight and then start it, it will read normal until it does it little trick again.



The Fuel shutoff solenoid is fine it tests out OK

I bought a fuel gauge test kit but it wont work on the older fuel systems; I am looking for fittings to make something work.

I thought that it might be the fact that the fuel tank was vapor locking due to a blocked vent so I unscrewed the fill cap but that didn’t have any effect on the system while it was acting up.





Thanks again guys for all the help





Twisted

 

[Forrest Nearing]

replace the rubber fuel lines between the body and engine... 2:1 that's your problem