Will old gas clogg a fuel pressure regulator

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Nov 29, 2009
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I have a fuel injected mpi marine 350gm engine in my boat. Tested the fuel pressure and it goes to 80psi when running. That's pretty much the max psi of the high pressure pump I believe. Funny thing is if you add some injector cleaner to the tank and add some fresh fuel it usually runs good, so I bet that screen gets clogged with old fuel. I'm not sure if it's before or after the fuel filter though. Pretty sure it's after. Any merit to my theory. The people who built my crate motor said the regulators last a long time except in boats typically because they sit a lot usually. The regulator was like $35 so I decided to order it and throw it on before removing the old one. Didn't feel like making the whole garage smell like gasoline while waiting for parts.
 
The regulator keeps the pressure from going too high. Did the new reg. fix your problem?
 
The regulator keeps the pressure from going too high. Did the new reg. fix your problem?
It's now running in the specified range, yes. The misfire and stumbling issue is worse than ever now though, so it didn't fix the drivability issue
 
Well, if old gas was suspected of clogging the regulator, even more I'd wonder about the injector(s) despite adding the injector cleaner, or have you not ran it long with the cleaner in the fuel so it may take longer to do the job?

What about pulling the plugs to look for symptoms, does it seem like it's multiple cylinders or only one that you might find by pulling the plug wires one at a time to check for running/misfire differences?

I know nothing about that specific boat-implemented motor. Does it have O2 sensors and an OBD2 code recording setup that you could use a scan tool on?
 
Well, if old gas was suspected of clogging the regulator, even more I'd wonder about the injector(s) despite adding the injector cleaner, or have you not ran it long with the cleaner in the fuel so it may take longer to do the job?

What about pulling the plugs to look for symptoms, does it seem like it's multiple cylinders or only one that you might find by pulling the plug wires one at a time to check for running/misfire differences?

I know nothing about that specific boat-implemented motor. Does it have O2 sensors and an OBD2 code recording setup that you could use a scan tool on?
It's got the 555 ecm i believe. Fuel injected it's a gm350 no o2 sensors. Usually if I add some fresh fuel and berryman injector cleaner it will run good, but then the next time I take it out it runs poorly again. I'm trying to take put the plugs, but the marine exhaust manifold makes it very difficult. The manifolds need to come off which I'll do this weekend.
 
If It was my boat, I would install a new gas filter, over dose it with fuel injector cleaner, maybe pull some old gas out of the tank, and add new gas. Then really run the boat to burn up as much of the old gas as possible. Old gas in a boat besides going stale, will absorb moisture just from sitting. Getting rid of old gas is the best thing you can do for it. That's probably all it needs to stay running good.,,
 
If It was my boat, I would install a new gas filter, over dose it with fuel injector cleaner, maybe pull some old gas out of the tank, and add new gas. Then really run the boat to burn up as much of the old gas as possible. Old gas in a boat besides going stale, will absorb moisture just from sitting. Getting rid of old gas is the best thing you can do for it. That's probably all it needs to stay running good.,,
 
It did run great when I filled it up with about 20 gallons and added a couple cans of injector cleaner and changed the fuel filter. Not sure which one did the trick though. It didn't stay that way though. The boat holds 120 gallons of gas
 
Ouch! That's a lot of gas to just dispose of it Sounds like you need to use your boat a lot more often.
Will old gas clogg a fuel filter quickly? I thought that was mainly a diesel fuel thing. It has a shchraeder valve on the fuel rail, and the fuel pressure is within spec, although I didn't test it under a load
 
Ouch! That's a lot of gas to just dispose of it Sounds like you need to use your boat a lot more often.
I wonder if the issue is more obvious in a boat motor, due to the heavy load? I run run stuff with gas that's 2 years old all the time and never have an issue. That side by side of mine sits in the garage most of the time. That gas is probably 2 years old now. It barely burns any fuel at all, so it's hard to use it up.
 
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