Archived No power following lift pump replacement

[KCramer]

This weekend, I noted a fuel pressure drop, after initially coming up fine. Following replacement of the pump, I have intermittent low power. The truck 'feels' like the turbo isn't spooling - won't pick up a load. I have no starting issues, and the engine runs smoothly. Fuel feed pressure runs 10-12 psi. I checked the air delivery tubing from the turbo to the intake, and don't find any leaks.



I have heard the vp44 failure results in a dead truck - may the loss of power also be a symptom?



This has got me baffled, since sometimes the motor pulls fine running through the gears, sometimes not.



Thanks for your thoughts... .

 

[KCramer]

Sorry - I meant to list the hardware details in the signature - obviously failed. Is a '99, 4x4, 6sp, 4:10s - stock, but for straight exhaust

 

[blacksheepdiesel]

Are you measuring fuel pressure before or after filter?

Godspeed,
Trent

 

[FourBarR]

you should get the codes read. need code reader for a 99. if its the vp- 44 code most common is 0216. all the best with it .

 

[KCramer]

Thanks all -

The fuel pressure guage is plumbed into the port closest to the driver's side fender on the top of the filter can, but I'm not sure if thats pre/post filter - the filter has been changed. The installation is temporary, until I can get the 'real' meter done.



I got the OBDII codes read and reset yesterday, there were two instances of 0236, MAP too high too long. The gentleman at AutoZone was very helpfull, and read/erased the codes even though there was no check engine light... . Following the reset, I haven't been able to note the lost power.



Does the OBDII code stored have any effect on the ECM?

Is it reasonable that the 0236 code might affect the wastegate?



thanks again,

klc

 

[mberry]

Yes, a bad MAP sensor would definitely affect performance.

 

[TheWolf]

would a bad map sensor possibly be my problem?? truck starts fine will idle fine, but you go to give it any pedal and it will act like it's going to stall. If you hold down on the pedal a little bit then it will eventually take some fuel for a second(rev up) then go right back down.

I just bought a gdp 392 to install. thought it might be a fuel pump problem. Happened almost 2 weeks ago and I haven't had time to mess with it yet. truck has 128K miles. this is 3rd gen truck and no I do not have a fuel pressure gauge yet.



Where is the Map sensor located ? is it the one on the air intake?



by the way can't remember the code it threw, but it was a low voltage something

 

[KCramer]

Limped the truck down to the shop, where they used a snap-on code reader - again, over boost codes (236 and another) were logged - still havent seen a check engine light.



With the snap-on reader, the indicated boost level in the manifold was 50psi (engine off), and the voltage on the MAP ~ 5V. Throttle position sensor read fine, and ran smooth from 0%-100% throttle. Disconnecting the MAP, the read voltage dropped to 0V.



New MAP on order (dealer part) to be installed on Monday - BTW Wolf - the sensor is on the intake manifold, rear of the engine, just in front of the firewall on my '99.



Thanks for the suggestions - I'll post final results Monday.

 

[KCramer]

The MAP seems to have been the root cause - may have preceeded the LP failure, as well. Seems to be running fine, now.



Thanks to all,

klc