Installed reman vp44 on a customers vehicle that came in not running - customer stated blowing a bunch of white smoke and would not go over 1400 rpm. Codes showed dead pump. Installed new reman. pump (i supplied) and a holley blue (customer supplied). Great pressure and flow. On idle after motor starts to warm up vehicle will idle with a lope from 500rpm to 1000rpm. I reset apps before starting and had batteries unhooked during job. CANT FIGURE OUT THIS LOPE!!!!! Please help. Customer does not like it, but I do. Sounds like it has a huge cam when its doing it.

 

I presume you have verified the CKP, or if one of the last of the VP trucks the CMP instead of the CKP, and the ECT, MAP and IAT sensors are good. Also, check the bypass valve on the banjo for the fuel return line to be sure it is holding specified pressure. If the bypass and sensors are good the symptoms would lead me to suspect the front bypass diaphragm is blown on the rebuilt pump, or the rear pump housing is seriously eroded and the timing shuttle is hanging up.

If the front pump diaphragm is bad the Holley Blue will provide sufficient volume to bind the timing shuttle until the internal pump computer senses the engine rpms are above around 1050.