Stall at high rpm

chrishelakdo110

Well-known member
Went for a ride this morning in woods, about 40miles from home via 2lane road, 55mph. On way home, at cruising speed, engine stalled, had very low power. Didn’t shut down. Was able to pull over, engine idled fine, and able to drive home without further issue. In effort to re-create scenario, I went for a short drive on hwy close to home. After about a mile driving at 55-60mph, engine again lost power, this time shut off as I slowed to stop. Was able to restart. No further issues to home, but ran st lower rpm, maybe 50mph. 1985 2.5L NAD. Any suggestions? No evidence of leaking fuel. Fresh diesel this am.
 

rocky

NAS-ROW Addict
Right about now, Professor Robert Davis is typing a suggestion that you need to add an electric pump near the tank.....
 

chrishelakdo110

Well-known member
That’s interesting. There was an electric pump in the cab that wasn’t attached to anything when I bought truck. Removed it cause I didn’t know what it was for, and it wasn’t hooked up
 

Uncle Douglas

Well-known member
Callsign: delete
Filter or air in fuel system.
Always start troubleshooting by changing in a fresh filter.
A single tank of diesel can clog multiple filters. Keep spares in your truck.

The injection pump can pull fuel through from the tank if the lift pump has died but will not enough to do high rpm.
Once drove a 110 with a failed lift pump from Burlington Vt back to Annapolis, just had to lug it rpm wise. That was a tdi though.
Looking @ your leaks thread, think you have already answered your own question, pump is knackered.
 
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chrishelakdo110

Well-known member
Filter or air in fuel system.
Always start troubleshooting by changing in a fresh filter.
A single tank of diesel can clog multiple filters. Keep spares in your truck.

The injection pump can pull fuel through from the tank if the lift pump has died but will not enough to do high rpm.
Once drove a 110 with a failed lift pump from Burlington Vt back to Annapolis, just had to lug it rpm wise. That was a tdi though.
Looking @ your leaks thread, think you have already answered your own question, pump is knackered.

Thanks a lot for the input Doug.
 

Northwind

Well-known member
Filter or air in fuel system.
Always start troubleshooting by changing in a fresh filter.
A single tank of diesel can clog multiple filters. Keep spares in your truck.

The injection pump can pull fuel through from the tank if the lift pump has died but will not enough to do high rpm.
Once drove a 110 with a failed lift pump from Burlington Vt back to Annapolis, just had to lug it rpm wise. That was a tdi though.
Looking @ your leaks thread, think you have already answered your own question, pump is knackered.

Uncle Doug,
 

Northwind

Well-known member
Weird, i was trying to copy and paste and add some comments. Anyhow, Uncle Doug you are the Defender God !!!
 

RDavisinVA

Technical Excellence Contributor
The fuel routing on the 2.5 is terrible because it traps air and then recirculates it around the IP filter loop.
Close off the banjo return to the filter with a solid bolt and install a sedimenter and 12V fuel pump to expose the air and or fuel leaks.
Better still. remove the 2.5 and replace it with something not dangerously slow.
 

chrishelakdo110

Well-known member
several questions today...

I changed my lift pump, and set out to change fuel filter. Turns out, my 2.5NA is running 200/300 TDI fuel filters. I bought the ones for the 2.5.
Fuel in the current filter looked clean though, no sediment in bottom. Not really sure what I'm looking for, but it really didn't look bad. Unfortunately, after changing lift pump, vehicle having trouble starting. Started fine at first, then died. I went through the priming sequence to get air out of system, and started again, but died again. Several rounds of this, but at end of day, I've got a truck that's not running, where as before it was.
- I noted some diesel leaking from fuel inlet port on lift pump with priming that I couldn't get to stop despite multiple attempts at re-threading. Didn't notice any fuel leakage when running for short periods. Could this be a source of air leak?
- Is it ok to keep running the TDI filters? i can return the several 2.5 ones and order some TDIs, or I can replace the TDI fitting and change out for the 2.5.
- Any suggestions about why won't start now, and how to trouble shoot? I think I must have air in the system? Seems like I"m not getting fuel. Tried priming it out, but limited success. fuel does pump out the banjo bolt, but only got a few air bubble out the air vent screw, no fuel.
 

rocky

NAS-ROW Addict
Wondering if the time has come to drop the tank and check the pick up for dirt/gunk/clogs. If that's clogged, nothing you do upstream is going to make a difference and would definitely trigger these fuel starvation type issues.
 

Uncle Douglas

Well-known member
Callsign: delete
several questions today...

I changed my lift pump, and set out to change fuel filter. Turns out, my 2.5NA is running 200/300 TDI fuel filters. I bought the ones for the 2.5.
Fuel in the current filter looked clean though, no sediment in bottom. Not really sure what I'm looking for, but it really didn't look bad. Unfortunately, after changing lift pump, vehicle having trouble starting. Started fine at first, then died. I went through the priming sequence to get air out of system, and started again, but died again. Several rounds of this, but at end of day, I've got a truck that's not running, where as before it was.
- I noted some diesel leaking from fuel inlet port on lift pump with priming that I couldn't get to stop despite multiple attempts at re-threading. Didn't notice any fuel leakage when running for short periods. Could this be a source of air leak?
- Is it ok to keep running the TDI filters? i can return the several 2.5 ones and order some TDIs, or I can replace the TDI fitting and change out for the 2.5.
- Any suggestions about why won't start now, and how to trouble shoot? I think I must have air in the system? Seems like I"m not getting fuel. Tried priming it out, but limited success. fuel does pump out the banjo bolt, but only got a few air bubble out the air vent screw, no fuel.

A couple things. The tdi filter head is an upgrade because the 2.5 and 19j setup recirculated air trapped in the system back into the filter head making bleeding very difficult.
2nd, diesel fuel is filtered down to microns- ie anything that makes it through to the injectors ruins them. If you see anything other than uber clean fuel you're effed. The smallest particle a human eye can see is around 40 microns which is a particle size that would ruin your diesel system. Cleanliness is imperative when working on a diesel fuel system.

You have already answered your own question,any fuel leak is a huge problem on a lift pump diesel system.
Air doesnt compress like fuel. The system is reliant on the injection pump creating very high pressure with the fuel that forces the injectors to pop open. The result is your injectors are not opening because the required pressure isn't being reached.

Stop cranking it until you fix the leak.
 
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RDavisinVA

Technical Excellence Contributor
It is almost impossible to bleed the air out of a 2.5 N/A using the lift pump.
Read post 11. It provides you with a solution to your problem.
Ignore the last sentence if you're keeping the 2.5 N/A.
 
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chrishelakdo110

Well-known member
Got everything bled and running strong. Put some transmission fluid in new fuel filter before i bled everything though. Started right up. When I was bleeding before, had no resistance on lift pump, so turned engine a couple times to get oriented correctly. 👍
 

chrishelakdo110

Well-known member
Bad news this evening. After getting all running strong.. seemingly... had s total shut down today. Truck just died 2 miles from home. Thought I ran out of diesel, so went and got some. Then looked st fuel filter... was full. Bled all for bubbles. No avail. Couldn’t get to start. Wouldn’t even try to start. Had to get a tow home. Clogged filter again?
 

Napalm00

Technical Excellence Contributor
Or bad fuel stop solenoid , or bad stop solenoid circuit .

With the key in the on position check the fuel stop solenoid spade for 12v.
 
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