Another fuel pressure gremlin.

Jonas Nordstrom · May 10, 2021

Put the motor (413) back into the car with everything new from the tank to the carb.

Now when starting the car the fuel pressure gauge fluctuates between 12-13 psi.
The pump is a Edelbrock 1723 (Rated at 6 psi.).
The filter is a 30 micron Hyperfuel 80113 (Also works for EFI.).
The gauge is a Summit G3122.
The carb is a classic Holley 650cfm with the two brass filters at the inlets.

Engine runs good, a bit rich but that could be that Im not finished with the tuning.
I can not see any flooding in the carb and I can kill the engine by screwing in the idle mixture screws.

Faulty gauge?

steve340 · May 10, 2021

Most likely. I have a little test rig and check calibration with air pressure.
I have never seen a mechanical pump produce twice the rated pressure.
One PSI maybe 2 but no more.
You could try taking out those horrible Holley sintered filters. I throw them away in any case.

451Mopar · May 10, 2021

Check the fuel gauge calibration. If it checks good, something like pressure relief in the pump is bad.

69a100 · May 10, 2021

Sounds more like you need a pressure regulator install after the filter and before the gauge. Good Luck

Jonas Nordstrom · May 10, 2021

69a100 said:
Sounds more like you need a pressure regulator install after the filter and before the gauge. Good Luck

Thanks. Really dont want to install a regulator so will try other things first.

451Mopar · May 10, 2021

I think the part description for the pump says it is 6psi. If it is double that, then I would think the pump has a pressure relief problem.
On the other hand, at 12psi, I would expect the carb to be flooding too?

steve340 · May 10, 2021

In a mechanical pump the pressure it can deliver is determined by the strength of the diaphragm spring.
I have fitted several Holley and Edelbrock pumps over the years - never had the problem you describe. They are very close to there rated pressure.
I do not think you need a regulator there is something else wrong.
Try taking out those filters like I suggested earlier - it is not hard and can be put back if you want them. It may be all that restriction in front of the pump.
Also check your gauge they are not that accurate usually.

451Mopar · May 10, 2021

steve340 said:
Also check your gauge they are not that accurate usually.

That is what I'm thinking? I have wasted money on junk fuel pressure gauges that don't read correctly, and seems engine heat really can mess some of them up even more.

Fran Blacker · May 10, 2021

This thread has info on excess fuel pressure .
https://www.forbbodiesonly.com/moparforum/threads/mechanical-fuel-pump-101.194336/

Another fuel pressure gremlin.

Jonas Nordstrom

Well-Known Member

steve340

Well-Known Member

451Mopar

Well-Known Member

69a100

Well-Known Member

Jonas Nordstrom

Well-Known Member

451Mopar

Well-Known Member

steve340

Well-Known Member

451Mopar

Well-Known Member

Fran Blacker

FBBO Gold Member

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