2004 225X ProMax - too much fuel pressure

[bb21xd]

I have a 225X with 43 hours on it. It makes 40 psi when you turn the key on. If you start it the pressure jumps up to 48 psi. Factory Service Manual says 39 psi +- 2 psi. We have replaced the regulator in the top of the VST - still have 48 psi idling. Any ideas?

[TheRickster]

Try removing the vacuum index line off the top of the reg and crank it and see what the pressure does.. Normally the vacuum reference will drop fuel pressure 3-5psi when running... Do not know why the psi would increase when you crank it..

PS> What is your Voltage when at rest Vs. Running? IF you have a regulator over Voltaging the system it could be running the pump in overspeed and the bypass regulator can't return enough volume....

Dunno...

Rick

[bb21xd]

No vacuum index line attached to the top of the reg.

Voltage at rest is 12.2, voltage running is 14.4-14.5.

Factory service manual says pump is capable of 90 psi, pressure reg. takes it to 39 psi +- 2 psi.

Is is possible that the float valve inside the VST is not working? This would allow too high a level in the VST resulting in a too small an volume for the regulator to relief into. This would create back pressure on the relief side of the regulator keeping me up at 48 psi when runnng.

[TheRickster]

I would take a pair of pinch pliers and squeeze the pressure side fuel line of the pulse pump when it is running and that will tell you if you have a VST float issue . IF it is running at 48psi and you pinch the pressure line out of the pulse pump and the 48PSI goes down to 40 within a a few seconds then it must be the float assembly..

Rick

[bb21xd]

That sounds very good! Let me ask this: Is it possible that if I had a hole in the diaphragm on the pulse pump that the pressure pulses would pump fuel but also make the pressure in the VST too high? The check valves is the hand pump bulb would stop the flow to the fuel tank so the 'excess pressure' would have to go to the VST. That is the next step - I'll go to the dealership and tell them to try that.

Thanks!
:D

[TheRickster]

Generally if you have a hole in the diaphragm it will flood the eninge rather than pressurize the pump..

Rick

[bb21xd]

10-4. I'll get my friend the mechanic at the dealership to try that. He spend almost the entire day on 3/23 on the phone with Mercury and then they had him on hold and just hung up. I guess it must have been time to go home for the long holiday weekend.

[bb21xd]

Been working with the dealership and now have a new pressure regulator and still have 44 psi of fuel pressure at idle. Engine still occasionally stumbles and/or coughs. Here is my issue: My engine never has had a vacuum line running from the barb on the VST's fuel pressure regulator to anywhere. I have been told that there should be a hose running from the fuel pressure regulator to a fitting on the intake plenum. My manual shows this hose also.

[props4u2]

Does the engine stumble and cough on the hose or in the water at idle? Every 225x I've ever ran on a hose lean sneeze's and sounds like you know what, put it in the water with back pressure and all is well. The fuel gauge used may be off some also. If it runs fine in the water you're hunting a ghost and paying for a lot of extra time. Have you mechanic check the tpi setting, we have seen them off many times also. I don't ever remember seeing a vacum line on the 225x regulators, they've all been open like you're's. I also disconnect the vacum line on all of our race motor regulators so the fuel psi stay's a constant pressure, never had a problem from idle to wide open.


Lee

[bb21xd]

Thanks for the info. I picked it up yesterday and tried it out. It ran fine on the lake for about 2 miles at 4000 rpm and then I picked up the pace to turning around 6500. Then it slowed to 5800 even though I had my foot to the floor. I slowed to 3000 rpm for a mile and then put it too the floor. It turned up to only 55-5800 and that was it. A couple of times it would feel like it wanted to pick up the rpms and it would jump up to 6000-6100 then back to 5800. All the filters are clean, fuel pressure at idle is too high but I am starting to think I have a bad coil - I'm going to look at the ignition coil ohms test next.

On the hose it runs fine except for coughing every 30 seconds to two minutes. If you slow to an idle when the engine was only making 5500 rpm then it sounds really strange when idling, smooth but strange. Almost like the timing is screwy.

[whipper]

your the 4th person this week with this same problem! Myself included. I thought timming also. It wasnt. Plugs and wires. changed both. Fuel? i think so! Fuel Pump. I think my fuel pump has had it or is on the verg of going. I can take her up to 6100 but should go to 6800. From 6100 after a few seconds with foot to floor starts looseing out to 5800-5900. The pump just cant supply that much fuel any more at WOT is what I think. Idle is OK not as good as it once was. On acceleration at the mid way point theres some times a studder also as the demand increases to the higher levels. Thats my take on it. Im going to put a new fuel pump in and see. I changed the little diafram spring and diaphram on the side of the motor by the VS also. That seemed to help just a little. Problems still the same but noticed the differance. thats why I think its the main pump. The little one made a super small differance that tells me that the big one just isnt doing its job very well any more. The tanks 8 years old so sounds about time.