Fuel pressure problem

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kenworth7985

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Joined
Jul 19, 2009
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65
I installed a raptor 150 quick connect with the draw straw v and big line kit to the vp44. At first the fp was real chattery and would randomly drop 10-15psi but never exceed 20psi at idle but driveing it was fine. Ive changed the quick connect fittings at the pump with the pushlock jic fittings. Its still chattery but not as fast, ive dropped the regulated psi to 16 at idle and it will drop to 12 ang go right back up. It still randomly dropes 10-15 psi although not as often and driving it does fine. Ive got an electric fp gauge in cab and mechanical under the hood both show the same. Any input is appreciated.
 
Did you put in the draw straw or did it use the factory pickup tube???

Chattering sounds like it is getting air on the suction side.
 
I just did away with all the quick connect fittings still no change, i pulled the module thinking it was running the fuel out of the bowl faster then it was taking it in i drilled four holes 2 half inch and 2 three eights. As before it will run set psi for a few seconds or a min maybe it will drop down to a lower psi it might go to 10,15,or 12 psi its very random. The truck does have a 1/4 tank of fuel but thought the holes would take care of that. Any thoughts would be appreciated.
 
Agreed, fill the tank and see what happens, if the problem goes away you are pulling air from somewhere in the tank.
 
I had the same problem and turned out it was the sending unit. But that's what I get for not goin with mechanical gauge.
 
Well i put fuel in and still no change, only thing ive noticed is it does not do it while driving, the pressure holds steady, but continues fluxuation at idle. Can anyone tell me what the difference is with the airdog kit? Ive also checked fuel psi with a manual gauge because ive had trouble with the sending unit as well. Ive talked to erick at vulcan and he thinks its in the plastic flex tube.
 
i have the exact same problem only with the airdog with filters. key on it holds 16psi, as soon as i start it, it fluctuates all over the place. haven't checked anything yet, but was thinking the draw straw is shot
 
I beleave to have fixed my problem, it was the flex line that comes with the drawstraw v. I had two drawstraw kits and used the other flex tube, there is a consdierable difference in there flexability. With the first one when the module would colapse in the the tank the line would leak when pressure tested. Thanks again for the input.
 
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