Engine/Transmission (1994 - 1998) Engine dies on freeway, under load (not new, right?)

[BFurton]

My first post because I've been able to glean the needed info from all the threads previously.

The truck; `96 long bed 3500 dually. 12 valve.
What's lead me to this very knowledgeable forum:

Back in July; engine died...side of the road. Truck on hook. diagnosis; lift pump failed. Replaced lift pump and fuel filter.
August; engine died...side of the road. Truck on hook. diagnosis; electrical, replaced auto shut down module and fuel cutoff relay along with fuel shut off relay.
October; engine died...side of the road. Truck on hook. diagnosis; Replace ignition switch, Fuel shut off solenoid
December 1st; engine died...side of the road. Truck on hook. diagnosis; Fuel over flow valve replaced. I tested the old one, and it was whistling @ 8PSI.
December 6th; received and installed 4 new gauges, including fuel pressure.
January 7th; ; engine died...side of the road. Got out, primed the fuel pump and the engine started. Drove to the TA truck stop about 1/2 mile off the freeway, when it died this time I had ~22 PSI to the P Pump. This could have been residual as I was towing and needed to get to the side safely and quickly and wasn't paying that close attention...

Looking under the hood, before priming; noticed that the fuel shutoff solenoid was in the correct locked position because I hadn't turned the key off yet. Then I cycled the key to see if it operated as intended, it did correctly. Then I primed it and it started. We spent the night in the truck stop and the truck started in the morning.

Because it is intermittent, I'm tending toward an electrical issue? poor ground? poor hot lead somewhere..???

Any thought will be much appreciated. We made it home safe about 80 miles, but reliability is now in question....

 

[BigPapa]

I doubt it's electrical. There's not much electrical on your '96 to give this problem.

From your descriptions, especially the "prime the lift pump and it goes" remark, it's bound to be fuel related. I would suggest you read the best 12V Fuel System write up written by Joe G. and see if you can't find your problem:

http://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html

 

[GAmes]

Although more common with the '94 & '95 injection pumps you could be experiencing warped plunger(s). The next time it dies douse the IP with cold water. If it starts right up you need a pump.

 

[BFurton]

Thanks Big Papa. I was rereading that greater than ever post on the 12V fuel system. I went out and "pinched the return line" and the pressure went up from ~18PSI to ~27PSI (was looking through a mirror positioned on the dash) and the idle increased maybe 200~300 RPM's.
Because this was the first haul after all the repairs, and now had a fuel pressure gauge to watch, I recall noticing that when I would take off from a start, the pressure would decrease to say around 13PSI, then ascend on up to the aforementioned ~22PSI. Kind of assumed that that would be normal???

 

[BFurton]

Thanks GAmes. I will carry some water with me Assuming that I'd dose it prior to priming it...??

 

[GAmes]

Yes. What happens is the heat build up in the pump keeps the plungers from moving freely. From what I have read, cooling the pump down frees them up and the engine easily restarts, then runs until the IP gets hot again.

 

[BFurton]

Yes. What happens is the heat build up in the pump keeps the plungers from moving freely. From what I have read, cooling the pump down frees them up and the engine easily restarts, then runs until the IP gets hot again.

Interesting, thank you!

 

[MLee]

Maybe a collapsed hose interior, restricting fuel flow, or the fuel screen needs cleaning because of a deteriorating fuel float. all causing fuel restriction.

 

[BFurton]

Maybe a collapsed hose interior, restricting fuel flow, or the fuel screen needs cleaning because of a deteriorating fuel float. all causing fuel restriction.

Thanks MLee. Some of the hoses got replaced during a couple of the other diagnostics/services - not sure which ones, but the 90* one between the lift pump and pre-filter for sure and the return fuel line from the P7100 looks new because I pinched it yesterday (as mentioned above). I'll check the records and do a creeper tour underneath and do the visual. Also, the heater was deleted and the screen was cleaned then - maybe about 1-1.5K miles ago? It wasn't very debris ridden then.

 

[BigPapa]

Do you know what your fuel tank level was when this happened?

 

[BFurton]

Do you know what your fuel tank level was when this happened?

BigPapa, the tank was @ 3/4 full. Flat and level travel w/39' 5th Wheel in tow. Speed was 61~63 MPH, light rain and about 58* ambient outside.
EGT ~950* Boost ~5-8PSI (that's why I say flat travel, not pulling a grade at all).
Engine temp ~160
transmission Temp ~150
Fuel Pressure ~22PSI (but that was just before I was ditching to the right safely, can't say that it stayed there the whole time). transmission was still locked up, so it kept the engine turning. When the transmission unlocked at about 35 MPH, the oil light came on and the engine quit turning altogether.

 

[BigPapa]

Just thought you may have a pick up tube issue at low fuel levels.

 

[BFurton]

Just thought you may have a pick up tube issue at low fuel levels.

Thank you again BigPapa! Not ruling anything out at this point. Could still be an in-tank module issue, I guess. The previous service guy had smoke tested the lines from the tank to the lift pump and from the P7100 return to the tank. Looks like the rubber portion of the return line got replaced, I haven't checked the supply side line to the lift pump yet, been busy and it's pretty wet outside right now. I did tow my 5th wheel back to storage, albeit only being a couple miles away - and no issues. I did notice that this trip, leaving a stop sign the fuel pressure drops to about 11PSI @ moderate throttle, 1,500 RPM's as I'm gaining speed and before the transmission locks up. It comes back up to about 18PSI after I back out of it at say 35-40 MPH (still 3rd).

 

[Missouri Mule]

Your Idle is 18 psi and when you squeeze the line your pressure goes to 27 psi. Pressure at idle should be 25 psi. As you push down on the go pedal psi should go up.
As I recall if pressure goes up when you squeeze the line your lift pump is the problem. If remains the same it is your overflow valve.

 

[BigPapa]

As I recall if pressure goes up when you squeeze the line your lift pump is the problem. If remains the same it is your overflow valve.

I think you have that backwards, Bill.

 

[BFurton]

Your Idle is 18 psi and when you squeeze the line your pressure goes to 27 psi. Pressure at idle should be 25 psi. As you push down on the go pedal psi should go up.
As I recall if pressure goes up when you squeeze the line your lift pump is the problem. If remains the same it is your overflow valve.

From Joe G's fuel system post: "The overflow valve looks like a banjo fitting, but it contains a pressure valve. The type shown in the picture has a spring, a steel ball, and a washer shaped like a tiny derby hat to regulate pressure in the injection pump. This is essential so there will be adequate fuel flow into the injection pump plungers when the fill ports open. The line from this valve goes to the rubber return line discussed in “Fuel supply and return lines” above. If there is low fuel pressure that is caused by a weak or defective overflow valve it is easy to check. While the
engine is running have someone watch the fuel pressure gauge. Clamp the rubber return line closed with some pliers. If the low pressure is caused by this valve the pressure read by the pressure gauge will increase very quickly. Do not hold the return line closed very long to prevent damage to the fuel system."

Since the OFV was replaced (Bosch P/N: 3165143426210 [2 417 413 101]) at the December 1st service, I hadn't focused on it. Now, because they installed it, I didn't get to verify it's release pressure in the jig that I created to measure the old one. The old one whistled at 8PSI. The fact that the pressure increases tells me that the lift pump must be OK? Right?

Thank you all again for your inputs!!!

I got the truck to the guru's on Thursday morining. They probably won't be able to get a look at it until Monday (9th) as they had a couple dead pony's in the shop as it was.....

 

[Missouri Mule]

Your right Big Papa I found old post (2008) when my brain had less files in it and found out I had back words (lucky tdr has search function. This time I put in black and white stored in a tdr file on my computer.

B Furton fuel pressure at idle should be 25 psi. Some where in the fsm it seems 20 psi lowest it should be as you increase rpm in neutral pressure go up to about 30 psi.

Your running 18 psi and when you squeeze the return line it goes to 27 psi.

So I'll get this statement right. When you squeeze the return fuel line if pressure rises its the overflow valve, if it stays the same or goes up slowly its the lift pump.

You are correct the overflow valve is quite simple, spring and ball. The spring tension is set at 22 psi. A round metal ball sits above the inlet to the overflow valve. The fuel in the pump presses against the ball when fuel reaches 22 psi the spring will contract because ball is pushing against and allows fuel to go into return fuel line. The spring can get weak and open up before it is supposed to.

On Mule a month after replacing lift pump Mule started up and died (lucky it was in my driveway). Had it towed to my mechanic. He said the ball was getting stuck in the inlet from the pump to the overflow valve. With 300,000 miles of fuel pushing up the ball I guess it got worn down a little. A new overflow valve (mainly new spring and ball got me back on the road).

 

[BFurton]

Thanks Bill. I will ask the shop to specifically check the (new) OFV out. Something gong on in that arena, for sure. I mentioned earlier that, not every time but several times anyway, when the foot is on the GO pedal a little hard - the pressure drop to ~11-13 PSI. So, I guess that is the only weak link as the pressure is being measured right at the input banjo connection to the IP and the OFV is at the opposite side and forward and if the fuel doesn't get used it gets returned.

 

[MLee]

As was posted years ago with the 12 valves fuel pressures, was Idle 20-22 psi at 2,000 rpm 30 psi. I got my replacement from www.Torkteknology.com these are adjustable pressure wise and a good price. They get there product out very fast.

 

[BFurton]

As was posted years ago with the 12 valves fuel pressures, was Idle 20-22 psi at 2,000 rpm 30 psi. I got my replacement from www.Torkteknology.com these are adjustable pressure wise and a good price. They get there product out very fast.

Thank you Mlee!