Having an issue. My truck is pulsing at an idle. everyone said it was my fpr. So i Took it to a diesel shop. They replaced the fpr , fuel filter, and its still doing it. They hooked it up to the computer, tested the injectors, good, tested the vacuum on the pump, good, but it shows that at an idle my rail pressure should be at 5000psi. It's jumping around any were between 4700 and 5200. Could it be a bad one right out of the box? Or is there something else I could look at? The problem is I will have to pay for labor again to reinstall a new one but the fpr I can return to the dealership. The weird part is that it only does it in drive at an idle. If I put it in neutral it goes away. And while I'm driving its fine and has good pressure. 02 2500 lb7
Pulsing
- Thread starter jhimes196
- Start date
I'm guessing they did a bottle test to check your return rates.... High return rates can cause a surge.
Tried it morning. It did it with heater controls on and off. Even switched to inside air, outside air, and ac. Just out of curiosity, would would the difference be and what would it tell you?
My LB7 used to have a up and down idle, by about 50rpm. when it did it, I would add a quart of 2 stroke oil to the fuel for a couple tanks and it would clear it up. I think it was the cp3.
Mine pulses when i'm driving by about 50 rpm and the transmission bucks under light throttle like the converter doesn't know whether to lock or unlock. It did it when my truck was stock 75K miles ago and does it today even after having all of the mods in my sig.
Any mods to pump truck like a lift pump? How many miles? The heater controls were probably mentioned because the truck will intermittently run the AC compressor while on defrost putting a momentary load on the engine.
No mods to the truck besides 5" exaughst with cat delete and a drop in k&n filter. Truck has 102 k miles. I'll try the 2 stroke oil and see if that clears up. What kind and ratio would you recommend? Can you test the cp3 pump without taking it apart? They tested the vacuum on it and it was fine.
IF your making good rail pressure 23k or so under hard acceleration I doubt the pump is bad. I have one in my area that does this at idle in neutral and in drive not moving as well as going down the hiway. haven't gotten a chance to do much troubleshooting on it yet though.
Mine does it in idle and a constant speed in drive but goes away when I hit the throttle. Mine is because I just put a modded pump in with the lbz regulator and its not tuned for the regulator. Are you sure the dealership didnt put a lbz regulator in by chance instead of a lb7 regulator?