Reckless32

I've been fighting a crappy fuel problem and even had to recently replace my port engine boost pump after it wouldn't even idle without dying. Fuel pressure gauge pretty much told the story after nothing showed up on the scan-tool. Now it runs great.

Running up river on Sunday, the starboard eninge seems to go into guardian mode at around 3000 rpm I swapped the fuel separator just eliminate another fuel issue, but it diod no good. Idles great and gets up on plane pretty sniffy, it's just around 3000 it gets crappy unless iback it off and let it run at around 2800. If I trim up both drives it'll go as far as 3200 maybe before it starts choking out.

I weould think if it were another boost pump it wouldn't want to run at all like the other before. Could it possibly be ne of the the MAP, IAC etc.? Anyone else have this aggravation?

mr mercruiser

you said it went into guardian-didnt you get an alarm??scan the motor for codes and check available power when scanning -at the end you said i weould think-DONT THINK-SCAN THE MOTOR AND WHILE YOUR AT IT CHECK THE FUEL PRESSURE UNDER A LOAD-if you find no codes-check the inlt screen on your lift pump-

speedygonzalez

about a month ago my brothers 496ho went into safe mode because his fuel was to old it spurred and would not rev over 3k. flushed fuel, new fuel filter,just like new now.

Reckless32

No alarms, just didn't want to run above 3k. It would just start choking out. When troubleshoting my other motor, wouldn't even idle, we checked the fuel inlet screen on that boost pump and it was as clean as new. That one turned out to be of course the boost pump itself. We suspect because it was choking thru big gulps of water from my tank (showing up in separator samples in a glass bowl reddish color with water) that the water burned the pump up. We suspect it's ethanol related since we went to ethanol here in VA back in May.

I did change the separator and strangely enough afterwards it didn't want to start at all until after several attempts. Then it went back to not wanting to get it above 3k w/ no alarms. Yes we'll get the scan tool back over and the fuel pressure gauge to try and identify the problem but that won't be for a few days, so I was trying to see if anyone else had experienced a similar problem and what it turned out to be for them.

Ted G

iTrader: (1)

Disconnect your neutral switch at the shift bracket and try it., It might think it's in neutral.

Reckless32

Well that's an interesting thought? Doesn't hurt to try I guess.

osen007

I just had the same problem in my 26 cat with a 502 the the cam timing was off 3 teeth I dont know if the chain jumped or what it was weird it cost me 4k to figure it out.

Island Hopper

If you had fuel problems in the past, and the boost pump inlet screen is clean, it may have worked its way into the injector screens. Check your spark plugs. If there is an abnormal amount of carbon build up, have them cleaned, or replaced.

Knot 4 Me

I had a bad boost pump that wouldn't show up until about 3,000 RPM. Also, check the in-line filter between the tank and the boost pump to make sure it isn't clogged.

MillerLite88

I just went through the same thing with my 496ho's. The neutral thing is great advice. That plug is right behind the shift cable bracket.

That didnt work for me........mine ended up being a temperature issue. Not really running hot but around 185+ degrees. I checked the impeller and I had a blade and a half missing off of it.

-Shoe