350 mag idle problems

[mfreez]

Yesterday it took several attempts to start my boat, starter engaged and boat immediately started then stalled approximately 5 times. It ran fine above 1500 RPM's. At idle it surged, stalled, and shut down.

A local mechanic was available, he connected the computer to the motor and found no error codes, all cylinders were firing normally, and fuel injectors are fine. He connected a fuel pressure gauge and found slight variations in pressure. He called merc, who suggested replacement of the fuel pumps, this module is 860 bucks:smt100


The boat has 65 hours and fuel is valvetech from the marina, no other boats with problmes that we know about so I am not suspecting wter in the gas??

Please let me know your thoughts.

I did search on idle problems and on 350 mag and did not find any recurring problems with the fuel pumps???? One suggestion in another post is the idle air valve? Is it worth trying this before the fuel pump module? How much does it cost, where is it located.

If you agree with the fuel pumps, where are they located on the boat/motor. Is replacement a DIY project, can I get the module from a alternate supplier for less?????

Posted this in sport boats, try again here, thanks for the advice.

 

[chuck1]

Just a side note, is it still under warranty with it being a 2007?

 

[mfreez]

??? I don't know, I bought it with 6 hours from a SR dealer in the southern part of VA, but it was originally put in service in May of 07. I purchased it in Dec of 07, so I guess it depends on the date of service in merc's database. If its under warranty, I am not so worried about the repair, just let merc pay for it, but if its not, I would like to minimize the expense (while doing it right)

 

[flflatrate]

if you pm me with your serial number I can see tomorrow if it has warranty. also you can get parts for those modules, you don't have to buy the whole thing. And what was the variation in fuel pressure? and if you need those fuel pumps I can sell you a complete module that was a take off due to corrosion where the water inlets are. ( meaning the fuel pumps are fine) for a fraction of a new one.

If you say you are starting it and it will run fine if you throttle it up but when you come to idle it stalls it could be the iac or even a very clogged iac muffler.

If the mechanic is telling you that you should try the module to see if it fixes the problem, I would try another mechanic. Doesn't seem like he knows whats going on. You don't want to waste $1000 if he isn't sure

 

[FamilyTime]

I had some problems with my fuel filters being bad, even though nobody else in the marina had problems. They cost like 9 bucks and the motor started fine after replacement. Just a note, take a little clean fuel and fill the filter before installing. Then let the fuel pump run a minute or two before trying to turn the engine over. If that doesn't work I would try the IAC. Spend the 100 bucks and if it doesn't fix it you have a good one for the day it does go out. The most you're out by doing this is 110 bucks, not 1000. Please respond with what fixes the problem. Good luck!

 

[gattlenn1]

IAC valve may need replacing !! On the 7.4 L, it's located in and behind the fuel intake manifold (just behind the flame arrester) . The price at m-max is $89.00 + tax. It took me
about 1-hr. to replace it, and it sure makes a difference!!

Hope this helps !

Ed.

Note: Ask the parts rep to copy you the Plenum and Fuel
Manifold section. You'll quickly see it's location.

 

[mfreez]

Thanks for all of the advice, and I will let you know what the problem turns out to be.

Found out today the warranty is in effect and should cover the problem. Now just to get the mechanic to have it ready for the weekend.

 

[mfreez]

Ok, The problem is supposed to be fixed. Mechanic called to say its ready. The problem was the IAC not the fuel pumps. He replaced the fuel pump module first on the advice of merc since it did not generate an error code on the computer. The fuel pumps did not fix the problem and he the replaced the IAC.

So? what do you think, overwhelmingly the consensus on CSR was IAC? Did the IAC failure cause smartcraft errors on your boats, was the mechanic wrong to not try the IAC first?

Ready to boat tomorrow:smt001,

Mike