Stalling condition

[79GLIDE]

Hope you guys can help me sort out a stalling condition that started suddenly a few days ago. My '90 stalls consistently during deceleration while braking. Many times it will stall under deceleration from 1500 RPMs, braking or not. It also seems to surge after a slight dead spot when I initially push the accelerator. It will also stall in park if I open the accelerator up to more than 1500 RPMs, then release it quickly back to idle. It tends to drop RPMs to just below 500, and then die. Last Saturday I replaced the glow plug relay and tach sensor. Running condition was normal for 2 days, but the trouble developed a day after driving through a hell of a wind and rain storm. It seemed to be idling a little low, so I adjusted it to 650RPMs idling in park. The stalling condition did not change. Operation is normal under all other circumstances, and it runs down the road with normal power. Any ideas??

 

[Black dawg]

When this happens, a good overdose of diesel kleen usually will clear it up. I would turn up the idle speed for a bit till it clears up though.

 

[gandalf]

Hope you guys can help me sort out a stalling condition that started suddenly a few days ago. My '90 stalls consistently during deceleration while braking. Many times it will stall under deceleration from 1500 RPMs, braking or not. It also seems to surge after a slight dead spot when I initially push the accelerator. It will also stall in park if I open the accelerator up to more than 1500 RPMs, then release it quickly back to idle. It tends to drop RPMs to just below 500, and then die. Last Saturday I replaced the glow plug relay and tach sensor. Running condition was normal for 2 days, but the trouble developed a day after driving through a hell of a wind and rain storm. It seemed to be idling a little low, so I adjusted it to 650RPMs idling in park. The stalling condition did not change. Operation is normal under all other circumstances, and it runs down the road with normal power. Any ideas??

The stalling on decel is a classic sign that the metering valve in the injection pump is sticking. That's not a good thing. The surging is also not good. I think that either a bit of air is getting into the system, or simply that the IP is getting old and wanting to be replaced. How many miles on the truck, and on the IP?

For the time being, fill your fuel filter with ATF, start the engine, and listen. As soon as the engine sound changes, shut it off and let it sit overnight. This allows the ATF to sit in the IP overnight. In the morning take the truck out and drive it hard, like you stole it. This will frequently clear the metering valve. When you fill the fuel filter with ATF, pour it slowly into the outer ring of holes. That way it will be filtered before it goes to the IP.

Let us know the results.

 

[icanfixall]

The filter fill with atf is a good idea. Can you tell us how many miles are on he injection pump and do you use any fuel additive.

 

[79GLIDE]

Mileage on the truck is 145,840, and the pump has never been touched as far as I know. I replaced the injector return lines 2 years ago, but recently it appears the cap and line on the driver rear injector might be leaking again. I ran ATF through it 3 or 4 years ago, and when I use fuel additive, I use Diesel Kleen or 911. It's been a while.

 

[icanfixall]

Thanks for the update on miles and fuel additives. My best idea is your pump is worn out but it can still be a stuck metering valve too. thats the simple easy fix if thats whats wrong. I sure would be looking at a rebuilt pump in the near future too. May as well do the injectors and return lines too. then you have a new fuel system worthy of another 25+ years of faithful service. Do have it timed after any injetion work.

 

[ToughOldFord]

My '92 did that when I got it. Come to find out the PO didn't believe in draining the water separator. The filter was completely full of water. Replaced the filter, no more problem.