2002 MerCruiser mx 6.2 mpi wont idle

[davedeman]

Just had engine rebuilt to standard specs < sent off fuel injectors had them cleaned and flow tested ,reinstalled engine with new plugs now it will idle till warm then cuts off . engine seems to be loading up. it has a black fuel line on the back of the hull it runs better when i disconnect the 2 wire temp sender . the fuel pressure is at 42 psi with key on then drops to 30psi with key off and holds , but when running at idle the fuel pressure gauge pulses from 45 to 35 rapidly ? any advice ?

 

[alldodge]

Welcome
Could use motor serial number to make sure what you have

when running at idle the fuel pressure gauge pulses from 45 to 35 rapidly

Pulsing fuel pressure may be the regulator on the fuel rail

Disconnecting temp sender will throw a code and can also supply more fuel. Sounds a bit like a vacuum leak, maybe the intake gasket

Need to put a scanner on the motor to determine what is happening

 

[davedeman]

i have a mercrusier mx6.2mpi serial # 0m324897 just rebuilt after melting # 6 piston
injectors have been cleaned and flow tested new plugs no codes and i have swapped map sensor and tested coolant sensor fuel pressure is 43 psi tps is in range at 056 at idle and opens smoothly to about 6.5 iac has been changed . engine runs good till it warms up to about 130degrees then it runs excessively rich . if i try to run it below 1000 rpm it will load up and cut off and will not or is very hard to restart with throttle almost halfway open . all spark plugs look the same very black but not wet i have rechecked all fuel injectors , none of them are leaking help ?!!

 

[Fun Times]

Some things to consider checking over!

Will the engine reach 160+ degrees? as it should.

How did you set (phase in) the distributor in place as there is a procedure or two to make it right..., https://manualzz.com/doc/23430314/service-bulletin---marinemechanic.com

The cap is not loose or the distributor base is not cracked where the cap bolts down to anywhere.... Rotor is not cricket.

Didn't miss a black ground wire during reinstallation such as a small one from the wiring harness (ECM) to the rear engine.

Fuel return line between pump/regulator to fuel filter base is not kinked as a blocked fuel regulator could cause a rich condition such as the screen under the regulator being contaminated.

Make sure the fuel pressure damper appears in good condition on top of the fuel rail, item number 13, https://www.mercruiserparts.com/bam/subassembly/31747/7585/90

Yours shouldn't have an inline fuel booster pump mounted near the fuel filter base assembly that might cause an odd issue.

Fuel Filter And Boost Pump(S/N 0M336102 And Up)

Fuel Filter And Boost Pump(S/N 0M336102 And Up)

www.mercruiserparts.com

The following is some fuel pump studding for you if desired, https://www.crowleymarine.com/sb/2/10858

350 MAG MPI ALPHA/BRAVO - 0M300000 THRU 0M599999

350 MAG MPI ALPHA/BRAVO - 0M300000 THRU 0M599999

www.mercruiserparts.com

 

[alldodge]

Merged threads, thanks for the SN

Symptoms look to be changing some between post.

 

[davedeman]

i will check these i have checked fuel rail pressure dampener, i did have a faulty fuel gauge
now i have constant 40 psi when running, engine runs well until it warms to about 130 degrees then loads up it does get to 160 degrees if i can keep it running

 

[dubs283]

There is too little information about symptoms to glean anything but speculation at this point

Like dodge mentioned early on you will need to connect a proper diagnostic tool and have the appropriate service manual to correctly troubleshoot your issue

It's in your best interest to look at data items with a diagnostic tool along with (WAG) 5 volt sensors, specifically ones that share a circuit with the temp sender

 

[davedeman]

does anyone know what compression # this engine should produce?

 

[Scott06]

does anyone know what compression # this engine should produce?

150 lbs relatively even among the cylinders

 

[QBhoy]

Second the idea of making sure that distributor is perfect.