cuda72

Hi all,

I have a weird fuel pressure gauge problem. I have an Isspro mechanical gauge with a needle valve and a snubber, plus the Vulcan big fuel line kit. The gauge is plumbed in the hose between the fuel filter and the VP44. I've always had 14 psi at idle and like 12-13 psi even at WOT (I only have an EZ). This Monday I replaced the fuel filter and when driving home from work on Tuesday I noticed that the fuel pressure would be 14 at idle but as soon as you touched the throttle it would quickly drop down to zero (I don't know if I looked at the gauge closely while driving to work on Tuesday).

So I thought it's either the lift pump or the fuel filter is bad. I had another brand new Fleetguard fuel filter, so I put that in when I got home, but no change. So I got a new lift pump (Carter 4601HP) and installed that tonight. After I got it installed I bumped the key and got 14 psi, however as soon as I start the engine it would drop down to zero at idle.

So now I'm thinking both lift pumps are fine and it's the gauge???? The gauge has been on there a year. Any thoughts? Anyone seen anything similar? Tomorrow I'll try removing the snubber and see if that works. I don't have another fuel pressure gauge, but I do have a big Sears vacuum gauge/pressure, but it only reads 10 psi. I'll see if I can rig that up to get a reading.....

Thanks for any advice or help.

Travis

Rauschbo

I wonder if the LP is continuing to run after the initial bump? Sounds like you get solid pressure with the initial bump, then nothing.....

Your idea to pull the snubber might be good, drain the line to the gauge, perhaps something is intermittently plugging that line (that's a WAG, of course)...

cuda72

Well... I figured it out after trying a different gauge...

I remembered back to what else I did that night I changed the fuel filter. I had also changed the oil and in doing so I had noticed that the fuel line that runs from the fuel filter to the VP44 was rubbing on the steering shaft, so I had wire tied it up off the steering shaft.

Turns out in doing so, I caused a major kink in the fuel line, so it really was drawing down the fuel pressure to zero So after fixing that, everything is fine again. So turns out the lift pump was fine.... I guess I have a spare lift pump now....... Wow, good thing I caught that stupid mistake before it burned up the VP44.

Thanks for the help.

Travis