Another fuel pressure question....

I checked my fuel pressure today after changing the fuel filter, at idle it was between 32-34psi. When I would rev it the gauge went no higher than 38-39 psi @ 9 pounds of boost at 5000rpm.

The max boost I'm seeing currently is 10psi but thats only with an actual load on the engine.

I didn't check the static pressure yet, I'm assuming from the other threads I read that it should be 39.5psi.

So, I guess my question is, is it normal to see that low of a pressure increase without a load or should I start looking for an issue.

BTW, I do have midly ported heads and intake, CMRE Stage 1 cam, stock bottom end, conical filter, ported manifolds and stock exhaust. So not to much done yet. Not sure if the cam might be an issue or not with the regulator.

Let me know what you all think, I get the static pressure tonight and post it.

Later,
Hock

Ok, key on engine off its at 0psi.

I squeezed the return line as tight as I could and it slowly went up to 22psi. Now I know that I didn't get it all the way pinched but what I did manage brought the fuel pressure up.

SO, I'm thinking bad fuel pressure regulator. What do you guys think?

Just in case the issue is a borked fuel injector, you might want to take a quick sniff of the oil dipstick so you can eliminate that random possibility.

KMT said:

Just in case the issue is a borked fuel injector, you might want to take a quick sniff of the oil dipstick so you can eliminate that random possibility.

Click to expand...

Ok, I'll do that since I just changed it last week it'll give a more accurate smell.

Static pressure should be 39 psi. Fuel pressure should raise equally to boost but doesn't drop equally to vacuum. As I remember, a driveway rev was useless for fuel pressure monitoring.

My fuel pressure guage is mounted in the cabin and, with it's peak hold feature, I can confidently calculate peak boost in the last run.