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-   -   Mrercury 700 dropping boost (https://www.offshoreonly.com/forums/general-q/342013-mrercury-700-dropping-boost.html)

Cash Bar 10-19-2016 04:21 PM


Originally Posted by easyrider1340 (Post 4492302)
...and just another reason to not run your boat with battery switches on both!! It makes your boat faster! :-)

I'll add that to my list of reasons when the battery switches thread comes back again. LOL!

Yeah, it would've been helpful to know the EXACT reason but since it seemed to work I wasn't re-fixing it. LOL

MER Performance 10-19-2016 04:30 PM

Even if you have a isolator you can't run batteries on both...it will still overvoltage the system causing ECM problems.

getrdunn 10-19-2016 05:36 PM

Assuming your feeling and seeing the diff in that one engine. Rpm loss coincides with boost gauge?

bblythe 10-20-2016 02:58 PM


Originally Posted by getrdunn (Post 4492923)
Assuming your feeling and seeing the diff in that one engine. Rpm loss coincides with boost gauge?

yes it is map sensor is good so is iac

Got Freedom? 10-20-2016 04:09 PM

Have you tried swapping the PCM with another engine?

GF?

bblythe 10-20-2016 04:23 PM


Originally Posted by Got Freedom? (Post 4493200)
Have you tried swapping the PCM with another engine?

GF?

yep no change

dunnitagain 10-20-2016 06:35 PM

That is a Bad Idea running batteries on Both , seen that melt an Altenator on the Port Engine smoke the wiring harness . Then burned the whole back off the boat!
The transients that the combined Charging systems setup, when combined, will wreak havoc on the ECMs. New Belt , New Tensioner then Id swap the ECMs and Boost controllers between Engines and see if the problem follows it

bblythe 10-21-2016 07:02 AM

did ecm swap new boost had it no the computer to check map sensor all good .

Got Freedom? 10-21-2016 09:13 AM

The PCM uses inputs from the MAP sensor, crank sensor (RPM) and the Throttle Position Sensor to calculate the signal it sends to the boost controller. Barring any mechanical issues with the engine you might want to try a new TPS. The TPS is a potentiometer and it might have a bad spot that is causing the output to fluctuate, which might explain why it works sometimes. BTW, the TPS is AC Delco part #213-911

GF?

bblythe 10-21-2016 02:08 PM

did compesstion check on all cylinders there fine tps cheap enough will try . would that throw a code . I got a race vision smartcraft display nothing


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