Glug glug after new IP, what's causing it?

[Mishka]

Motor hesitates after letting off throttle after installing a new IP pump and I can't figure out why.

Also how does the timing sound?

Glug glug - https://vm.tiktok.com/ZTdDwPJKk/

Sound after installing new IP - https://vm.tiktok.com/ZTdDwR3aG/

 

[franklin2]

How much have you experimented with the IP timing? If you don't have a meter, it's going to be trial and error.

 

[Black dawg]

are you talking about the idle stability after it comes down to idle?

 

[Mishka]

Yeah I'm talking about the instability right after letting off the throttle. It's like it wants to die but instantly goes back to idling fine

 

[Mishka]

Turning it towards driverside seemed to help some but still did it. It drives fine outside of transmission but that's a whole different issue I'm trying to get fixed with a new TPS sensor (worked fine before IP swap)

 

[Cubey]

Yeah I'm talking about the instability right after letting off the throttle. It's like it wants to die but instantly goes back to idling fine

That can be the metering valve. My RV had very questionable old diesel when I bought it. It had weak idle when in gear and sometimes stall when I let off the throttle at low speed but otherwise was drivable. Once I put in fresh fuel and drove it a hundred or more miles, it was fine again. In my case it was a sticky metering valve that was probably gummed up. Fresh fuel was enough to clean it up thankfully. In your case, maybe the metering valve is slightly borked on your new IP.

 

[Black dawg]

Metering valve might be a little tight, or something else in the gov assembly......I would give it some time. On the tps for some reason I didnt see that you had replaced the pump. I would disregard your old voltage setting, as pumps can be slightly different pump to pump (throttle lever position vs Engine rpm).

 

[gandalf]

Tell us about your new IP. Is it a "new to you" IP or is it a freshly rebuilt IP? If it is freshly rebuilt, what shop did the rebuild?

You're aware, I'm sure, that all rebuilders are not equal. They range from "clean off the outside" to excellent. The quality of the rebuild is critical.

I'll agree with the opinions stated above--it sounds as though the metering valve is sticking.

 

[Brian VT]

Maybe a fuel filter full of ATF might loosen it up?
Just brainstorming based on things I've learned here.

 

[Mishka]

I got the pump from classic diesel design, it's their stock N/A rebuild so it should be good. My diesel is clean, fresh fuel filter and I run hotshot secret EDT diesel treatment, however every 6 months I run their diesel extreme for a deep clean and that's currently what's in the tanks right now.

I'll try messing with the timing again.

 

[Mishka]

My lift pump was replaced 6-8 months ago with a duralift 40222. Truck ran amazing till the FSS failed open and I had to suffocate the motor to get it to turn off forcing me to get a new IP pump.

 

[Cubey]

My lift pump was replaced 6-8 months ago with a duralift 40222. Truck ran amazing till the FSS failed open and I had to suffocate the motor to get it to turn off forcing me to get a new IP pump.

An easier way to kill it in that situation is to cut or otherwise disconnect a fuel supply hose before or after the lift pump, and let it run out of fuel. With an electric pump, pull the fuse or turn off the ignition switch first so it won't keep trying to pump when dry. With mechanical, just disconnect the supply. YEah you'll have to air purge next time but eh, that's still easier than suffocating it. Or at least it would be on my RV with it's open/exposed ATS 085 (~1980 Porsche 911) air filter that they had to rig up with a retaining wrong instead of the air box lid to fit on the engine compartment.

 

[Mishka]

Yeah unscrewing the fuel filter probably would have been best but I panicked. I first turned off the pump (on a switch) that didn't work so I unplugged the IP but that didn't work either so I was in panic mode

 

[Mishka]

I really hope I don't have to deal with a warranty issue on the pump, trucks been sitting for far to long I've only got to drive it once since getting pump back in December

 

[Cubey]

I really hope I don't have to deal with a warranty issue on the pump, trucks been sitting for far to long I've only got to drive it once since getting pump back in December

You might just need to take it out on the highway for a couple hours to fix it. That with fresh diesel sure solved it with my RV when it sat for who knows how long before I bought it. In fact it couldn't even be started, much less driven at first, the seller had to go buy a piece of 5/16" hose for me to stick on the return line on the rear of the engine. The hose was rotten and had a split. Once that was replaced and the air was purged, it started up.

The weak idle and stall it had:

xc_hide_links_from_guests_guests_error_hide_media