Mercruiser 350mag mpi Stall problem 2003/04

Hi Guys, i fitted this brand new unit into a 2000 235 chaparall in 2005, i haven't a any problems until the back end of the last boating season (oct 09) when i went to run it out of the water for winterization, it started okay and ran for approx 5 to 10 minutes then stalled. anyway i did winterize it and thought it was a blocked fuel filter, anyway come this spring changed fuel filter checked fuel in tank, fuel was low but i did do a visual inspection of the inboard tank and it was very clean and replenished fuel , ran again for five mins then stalled again , got local dealer to check iac valve and that was okay, now it does start but inmmediately stalls. i also checked fuel line from tank to fuel filter and that was clear too , this engine has only done 60hrs use , there was fuel on the top rail of engine block runninig to injectors by purging the valve ,the fuel pump does make the sound of priming itself upon turning the ignition on , so where do i go next ? do i change the fuel pump and has this been a familiar problem to other 350 mag mpi's ? thanks guys, from across the pond .

Re: Mercruiser 350mag mpi Stall problem 2003/04

fuel pressure regulator?

Re: Mercruiser 350mag mpi Stall problem 2003/04

I stripped off the fuel pump and took it to local fuel injection specialist, came back as pumping fuel at 43psi which is standard, if you take the vacuum pipe off it goes to 45psi, i put the fuel pump back on the engine and fitted a temporary fuel pressure gauge on the fuel rail which when running the gauge stood at 43psi but the engine still stalled. i've now sent the boat back to local dealer to re check iac valve. at least i've saved money on a fuel pump and fuel pump regulator, gone further away now, checked plugs, leads, dizzy and rotor arm, all okay too , have you guys got any comments or ideas ??????

Re: Mercruiser 350mag mpi Stall problem 2003/04

now it does start but inmmediately stalls.

Click to expand...

Ayuh,... So is it loosing Fuel,..?? Or Fire at that moment,..??
If Fuel, is it electrical, or lack of the fuel,..??

Even bein' a 'puter motor, visual observation,+ a Test Light can answer that question...

'course, a scan 'puter makes it Easier...

Re: Mercruiser 350mag mpi Stall problem 2003/04

I believe they are supposed to run at 30 psi, but I could be mistaken. You'd have to check the book. If its above spec, replace the fuel pressure regulator.

Re: Mercruiser 350mag mpi Stall problem 2003/04

Done that guys, when i took the fuel pump off , its says on it 'v8 alpha 43psi', when i ran it with the temporary gauge on the fuel rail , it came back at the correct pressure (43psi, 45psi with the vac pipe off), with original the simptoms we would think fuel pump/fuel reg. so where to go next ?

Re: Mercruiser 350mag mpi Stall problem 2003/04

Got sorted today guys, went through the engine , iac valve, coil, dizzy etc, turned out to be the tmap sensor , part number 885165, runs like a dream now, can anyone tell me the cheapest place to buy one of these ?

Re: Mercruiser 350mag mpi Stall problem 2003/04

Got one sorted now $175 dollars plus postage back to blighty , i'm posting this for any future problems for anyone else not just me, have fun this summer. Scouse Boater