Most owners complain of low fuel pressure, but I have just the opposite problem. At start up the pressure reads 15psi. At shutdown the guage reads 10psi. I have to use the screw on the sender to bleed off the pressure to get the gauge back to zero. After some hard aceleration the pressure built up to 27psi before I stopped to bleed it off. Initially I thought this was a sender or gauge problem and replaced both. Same problem with new parts. (Now I have spares.) This is a mechanical diprocal gauge and sender. A flex hose connects the fuel pump schrader valve to the sender. I have the Vulcan Big Line relocation kit with a carter fuel pump mounted on the frame rail.
Does anyone have any ideas what would cause the pressure in the flex hose line to remain high and not drop down to zero at engine shut down? There are no codes or check engine light. Is this a sign that the VP44 is failing?

 

I thought the VP44s didn't like more than 20 psi?

 

I don't know what the max. pressure they will run to but according to the guage it had built up to 27psi. I made several hard runs dropping pressures to about 7. Immediately after each time backing off the throttle the guage read higher than the last. Since both guages and senders did this I believe something is wrong with the pump. The pressure does not go over about 15psi under normal driving but won't drop below about 7psi after shutdown. Could it be that both senders have failed or is there something in the pump that should bleed down but isn't? Thanks for any suggestions offered.

 

around 15 is the norm for idle 7 wot is fine, above 15 could be bad for the vp(so iv read), i would run a diferent pres. guage to make sure you have an accurate reading, then i would get it looked at

 

I ran 45psi for 3.5 years and had no problems with the pump, I don't know why it would be staying up though

 

This thing has me stumped. Would running the Injection pump without the schrader valve cause harm? Since I have replaced the gauge and sender without a change the problem must be in the pump. Hasn't anyone had these high pressure readings and no bleed off?

 

does the pump have a way to adjust the pressure? i've heard some do. as far as the pressure dropping back to zero with a mechanical gauge personally i would think something was wrong with the pump if it did that. someone will correct me if i'm wrong i'm sure but i think theres a check valve in the pumps that will not allow pressure to bleed off so you always have fuel when you go to start it. and to prevent air from being in the line.

 

Thats the highest I've heard someone admit to on a 2nd gen Lets just say I have a 0-100 guage that was sitting at 12:00 I've heard of a couple guys blowing seals on the vp, but also know several who don't have any problems with 30+ psi.

When I ran a carter pump on the frame I couldn't make 20 psi so I'm thinking this is still a guage problem =\

 

The truck has sat for three days. The guage read 9 PSI until I bleed it off at the sender to get it to read zero. I don't believe it is a guage problem since both guage and sender have been replaced and the same condition exists. The plan is pull the valve stem out of the schrader valve and replace the flex hose with a plain grease gun hose. If this doesn't stop the system from building high pressures incrementally and holding pressure after shutdown my next step will be our local pump/injector builder. Fortunately they have a good reputation and don't mind sharing their knowledge with plain folks.