Engine/Transmission (1994 - 1998) Fuel Starvation

[SDockery]

Yesterday my "water in fuel" light came on . I drained the filter using the drain valve (water in fuel light went off and has not been back on). Later that evening, the truck acted like it ran out of fuel (no throttle response, stutters and dies). I did the manual air bleed procedure. Truck started and ran for about 10 minutes for me to get home. Changed fuel filter. Cranked truck. Started, ran, went to bed. This morning I hopped in and headed to work. Truck died about 3 minutes out of the driveway. I pulled over and cranked the engine in short bursts til it fired up. Drove home. Didn't quite get back when engine died again. Coasted into drive way. Did manual air bleed again. Cranked engine in short bursts. It fired up and idled for about 30 minutes. I figure it had air or something in the line, pull out, make it about 500 feeet past the place it died the first time this morning and it dies again. Crank in short bursts. Starts, limp home. Did manual air bleed again. It's currently idling outside. It acts like it will idle all day.



I"m stumped... .

 

[Johnstra]

Check your fuel shutoff solenoid. Since your truck cranks and idles, while it's idling, see if you can pull the lever up. It should be all the way up. If it's not, you can zip tie it up to keep you going until you can replace the solenoid. There's also a 70A relay for the FSS that can cause problems if it's not working right.

-john

 

[SDockery]

No Dice. Lever is in the run position, and feels like it won't move. With the truck off I could easily move the lever.

 

[Johnstra]

A fuel pressure gauge would help if you can get your hands on one. Sounds like you have crappy fuel or an air leak. If you have good pressure, I'd suspect bad fuel. If the pressure is low, you could go after the usual suspects for air leaks: leaky supply return lines, fuel heater, 1/2" line between fuel heater and lift pump. Also check the OF valve and the pre-filter screen if pressure is low.

-john

 

[Joe G.]

What John said. The lift pump has a hard time pumping air.

 

[Signal73]

If it was running ok before you drained the WIF sensor, then ran crappy afterwards Id look at the drain as the primary suspect. If not that, Id say ya got a load of bad fuel or maybe gasoline

 

[bmoeller]

If it was running ok before you drained the water, then ran crappy afterwards Id look at the drain as the primary suspect. If not that, Id say ya got a load of bad fuel or maybe gasoline

Second that.

 

[SDockery]

Thanks for the suggestions. I suppose I should be thankful for the oppurtunity to learn my trucks fuel system, right?



Pulled the fuel filter. checked drain operation. Not sure what to look for? If it was bad how could you tell? Put fuel filter back on (this is the new one I put on Wednesday night). Truck is still acting like it runs out of fuel.



Symptoms:



Idles fine.

When driving above 1200rpm can push on go pedal and nothing happens, after this the engine stimbles, and dies.

Engine refires after cranking for about 15 seconds. Idles rough at about 500 rpm then comes up to stock idle.



Questions:

What does a clogged injector act like?

Should I change the fuel filter again?

Where should I be checking the fuel lines for air leaks?

Would bad fuel kill my engine like this?

Should I siphon the tank and put new diesel in?

 

[SDockery]

Pulled the fuel heater and cleaned the screen. Drove about 500 feet and dead. seriously dead. Manual prime does nothing. Cranks but it's not getting any fuel. Lift Pump? Price?

 

[Joe G.]

The fuel heater does NOT have a screen. The screen is below the fuel heater in the same assembly. The fuel heater is the plastic thing above the screen that looks kind of like a hockey puck. What happens is that the heater element burns out and melts some of the plastic. This causes an air leak around one of the pins in the electrical connection. You can test by removing the fuel heater. It takes an 8mm allen wrench. Remove the screw that holds the fuel heater. Put the screw and the fuel heater aside. The pre-filter part with the screen will bolt right up to the mount without the fuel heater. Take it for a test drive and see what happens.

 

[SDockery]

Okey doke I'll give that a whirl.

 

[Vaughn MacKenzie]

Another possibility is the screen on the tank pickup assembly is plugged. When we dropped the tank on a NW Bomber's truck to replace the fuel level sending unit his screen was pretty clogged. I've never seen that on the other 3-4 trucks I've seen with the pickup assembly taken out of the tank though but if you've gotten algae or a bad tank of fuel that could potentially be it. To check disconnect the rubber hose off the hard line that goes into the prefilter assembly and see if fuel can be drawn through the line when putting a vacuum on it.



Vaughn

 

[KYOUNG]

You can disconnect fuel lines from gastank and substitute tank with 5 gal of fuel to tell if you are having tank problems!!!!!

 

[MLee]

SD;

did you change your fuel filter? when you had it off. water plugs a fuel filter, very little fuel gets through. Just a thought.

Marv.

 

[SDockery]

MLee, Yes I changed the fuel filter when I had it off on Wednesday.



Joe G. , is the allen screw located on top of the fuel heater/seperator housing right next to the pigtail connector?

 

[Joe G.]

NO! That's the AFC access to the star wheel.



Take the pre-filter off the bottom of the fuel heater/pre-filter assembly. There is a large shiny screw that the pre-filter screws into. Remove that. Then pull the black plastic fuel heater down. The screw is really an adapter. It has the same threads on both ends. Install the pre-fiter where the fuel heater was. Use one of the two ring gaskets.



This is the last easy test. If it does not solve your problem then you have to take the lift pump off and do the bucket of water test to find the leak.



Here is what the screw and the fuel heater look like.



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[SDockery]

AFter I posted this morning, I went back out and looked and found what you're talking about above. Removed the heater and put everything back together. STill causing a problem. I'm going to run fuel lines to a five gallon can to see if my problem is in the tank.

How big a deal is pulling a lift pump? THanks.

 

[Joe G.]

Pulling the lift pump is not too bad. It's kind of a PITA to put back. You an test it by removing the short curved hose. Hook up a hose from a bucket of diesel to the fitting. Remove the output steel line and install a hose there to an empty bucket. Jump the starter and see what happens. If it pumps fuel ok, then the lift pump is ok. One guy found a bad air leak in the supply fuel line on top of his tank. Another found a bad air leak in the fitting on top of the fuel heater/pre-filter assembly. Another found that the curved hose was bad.

 

[TRCM]

I found the factory line between the tank and the hardline on the frame almost crimped shut.

 

[biggy238]

Secure the return line because if you LP is still kicking, it will move ALOT of fuel.



Is all of this with a mostly filled tank of fuel? There are some pictures on here and in the last TDR issue that show where the screws on the pickup in the tank wear into place and can hold the pickup above what should be empty. I believe I had mine ran out prematurely twice because of this. This was confirmed by miles driven and gallons of fuel needed at next fillup.



Also, there are two compression fittings beside the bell housing, one supply and one return. These are where the steel lines connect to the braded lines. They are the only things I see left that haven't been mentioned.