Thread: 951 Max RPM loss
03-18-2009, 05:40 PM #1
951 Max RPM loss
What would be the most probable cause for this? I know the question was asked a while ago but I am still chasing this problem. I have perfect compression(135 psi) and fuel system is new. I've cleaned my raves a couple times now, also inspected and cleaned my water regulator. Only turning about 6450 max. I know it's not a huge deal but it's something i'd like to figure out. Any ideas? Thanks in advance.
03-18-2009, 09:36 PM #2
That comp is a little low (stock 150) but if the cylinders are even it is likely ok.
Around 6500 is where a 951 will turn without RAVE valves. The RAVEs are opened by that solonoid just above the head and the solonoid is commanded by the MPEM and powered via a hose from the rear case (right beside the pulse hose) with a check valve inline to only allow pressure, but not vacuum from the case.
If the solonoid does not work, or the supply line to it is cracked/clogged, or the check valve is bad, you will not have RAVEs.
A simple check is to pull the electrical connector off the solonoid. If you do not lose any rpm the RAVEs are not working. If you do lose rpm, they are, and you have something else dragging you down (an issue in the pump, perhaps).
03-19-2009, 03:30 AM #3
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03-19-2009, 05:41 AM #4
03-19-2009, 10:41 AM #5
I found one of the easiest ways to check was to pull the springs out of the raves. If you gained your RPMs back then go backwards from there. The line to the raves the check vlave then to the selenoid. My wire fell off one time out on the lake and I found it right away liike that
03-19-2009, 01:24 PM #6
I have never seen a stock 951 have 150psi stock, 145 max from factory is the most i have seen.
03-19-2009, 02:47 PM #7
Awesome thanks for the many replies, you guys are great. I'll do these checks as soon as the weather gets nice. I was told that OEM compression on a 951 was 135 psi at sea level.
03-19-2009, 03:44 PM #8
Compression guages vary. If both your cylinders read 135, i doubt that has anything to do with your problem. I would pay close attention to the raves and the water reg.
03-19-2009, 04:58 PM #9
I got an '02 GTX carbed sitting in the carport right now with 165hrs on it that will pump 150psi till you kill the battery. It is bone stock with the original Canadan silver paint on it. It has the same reading on three different guages (with two different types between them).
Perhaps it just has a really good starter.
Guages vary, as well as engines.
Let us check with the studio audience...
In the end it does not matter since that is not his problem.
03-20-2009, 01:04 PM #10
So last night i started to inspect everything in general. I looked at that solenoid above the raves, disconected it and looked at the contacts and it looks brand new still. Still has fresh factory silicone grease in there.
I also took the rave caps off. Here's my question: With those rave caps off, should the rave valve springs push the rave up all by itself? When I took the caps off and pushed the raves in manually, they only pushed back up halfway. I had to pull on them to get them to come back up all the way. Could that be a problem? Do the inner springs inside there wear out? Thanks again.
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