Thread: fuel pressure
08-29-2005, 12:51 AM #1
Hey Mark, you said 1.5 psi fuel pressure at idle and 5-6 at wot. I measured 0.5 idle and 3-4 at wot. This with a 65 mikuni main in the return. If I pinch the return off totaly it is the same at idle and 4 at wot. Is something wrong?
08-29-2005, 08:49 AM #2
It sounds like the same problem I'm having right now. It is 630am and I'm in the process of taking off my Riva Power Shit carbs for inspection.
I'll let you know what I find.
08-29-2005, 09:04 AM #3
maybe your check valves have blow by..leaking.. creases? ..you're not building pressure obviously and the ck valves control the pump seal, although case vacuum is the actual vac force.... hopefully not a case leak.
jus' thinkin out loud.
08-29-2005, 09:07 AM #4
Good point. I have a vac/boost gauge buried around here somewhere. Think I'll rig it up and verify I have that pulse signal!!!
08-29-2005, 10:35 AM #5
How sure are you about those pressure numbers? Have you seen them before with stock carbs/stock fuel pumps?
08-29-2005, 10:59 AM #6
Damn sure, as long as you have your pressure gauge mounted on the carb side of the restrictor jet.
Found a double creased check valve on the number2 carb.
Pics in a moment.
08-29-2005, 11:10 AM #7
Note the pulled up areas around the pump check valves. It was giving me zero pressure at idle, and not much more than zero at WOT. The carbs were starving.
I was the problem here. I installed this checkvalve incorrectly, and fugged it up.
08-29-2005, 12:49 PM #8
Ahh, I see grasshopper. Well, mine has 4 plus at wot. Any idea what it should be with the return blocked off (deadhead pressure)?
08-29-2005, 12:53 PM #9
Don't know. I don't have any way to check stock I bodies with the return blocked off.
However, with a 60 return jets on a set of carbs jetted 110p, 125m, I was reading close to 7psi at wot, and a tad over 1 at idle.
Yours sounds really low. Is your gauge working properly.
08-29-2005, 01:39 PM #10
will try another gauge tonite. I wont have time to tear it down, wonder if I can install a low pressure electric pump?
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