Engine/Transmission (1998.5 - 2002) Air Dog Pressures

[Wyomingcowboy]

I have a question for all the Air Dog Pros... .

I am trying to show my students how to check fuel pressure today and using my truck as an example.

1. I had to remove a banjo bolt to replace with the schrader valve and I lost no fuel when I pulled it out of the pump. I have always lost fuel out of the VP44 when I did this before. Anyway, the motor didn't hesitate or choke when I restarted it as it has ALWAYS done before.

2. After attaching gauge, the fuel pressure fluctuates between 10 and 14 constantly. Is this normal? Sometimes it crawls slowly up to 14 and then immediatley drops to 10 but usually it is very fast that this happens. Does the Air Dog have a factory relief spring set at 14 psi?

 

[Bob Cochran]

I will take a shot at this at least from what I have seen. My fuel pressure is pretty solid at 15 PSi at idle. I don't connect at the IP though I disconnect and connect the mechanical gauge before trucks sending unit for the trucks electric fuel pressure I installed years ago.

Years ago a lot of people was destroying the fuel sending unit when first installed. At that time I think everyone was connecting the sender directly to the IP like you had the mechanical gauge. Most was getting I guess you would call it a hammering of pressure from the IP so everybody was adding a snubber to protect the sending unit. You might consider adding a snubber and see if that helps.

Most every ones solution later was to add a couple of feet of flexible fuel line to the sender mounted on the firewall. Remote mounting of the sender helped prevent sender damage do to engine vibration/heat and lessened the hammering of fuel pressure. As a belt and suspenders kind of deal some added the snubber and flexible line.

I added flex line and snubber on initial installation so never experienced this personally. I am sure others can add to this information and hope it helps a little.