6.2 mercruiser no power under load

[Ceboyett]

Rebuilt the motor installed ran one good time evidently the timing wasnt set properly and detonation got 3 cylinders. Rebuilt again was running rich. Never put it in water. Timing set at 8 Btdc, took to shop to run diagnostics. All sensors reading as required ( changed them all anyway) new cap ,rotor, wires and plugs. Fuel pressure 38 psi. Ahhhhhhhh so theres the prob. Mercruiser says suppose to be 26-28 and NEVER to exceed 30. Ok new regulator she fires right up purrs like a kitten and not running rich. Change plugs again no she will not run up off idle under a load? What now?!

 

[Ceboyett]

Serial # 0m078518

 

[alldodge]

Mercruiser says suppose to be 26-28 and NEVER to exceed 30.

Guess they need to change their manual 31 (5.0, 5.7, 6.2) because I'm seeing 43 psi at 1800 rpm, the V6 manual 32 shows the same

 

[Ceboyett]

Thats what i said after looking it up. Bur he said that older model 6.2 was only 26

 

[alldodge]

You have the first gen 6.2 and my manual was printed in 2000 so I'm real suspect. Hey muc or Fun Times can you verify

 

[Bt Doctur]

If a TBI 31 psi, if MPI 41 pst at the rail. For an MPI timing is not adjusible

 

[Scott Danforth]

TBI is a 2-bar system (28-30 psi), MPI is a 3-bar system (43-45 psi)

 

[Bt Doctur]

using that serial number I get 6.2 MPI Bravo presure at the fuel rail should be in the 40-43 range

 

[alldodge]

When I look up 0m078518 it comes back with MPI / Bravo

 

[Bt Doctur]

Dyslexia strikes again
Dont know how your setting the timing cause it all done by the ecm, you drop the HVS in with the rotor on its mark and go.

 

[alldodge]

I am seeing the TB-V distributor at BAM and Merc site, along with ECM part number 862904T1 which should be the MEFI 3

 

[Bt Doctur]

I confirm Dodge, so used to the newer HVS 6.2`s that I worked on

 

[Ceboyett]

As far as the timing mercruiser said using a scan tool put it in base timing mode set it at 8 then put it back in normal then let the ecm do the rest. I ordered the part number 807952A1 fuel pressure regulator per engine serial number.

 

[Fun Times]

MERCRUISER 6.2L MPI BRAVO, Engine Model Number 4R42027N1.

Fuel regulator part number 807952A1 is the correct one which is a 30 psi unit so you should be good there especially since it noticeably stopped running rich for you....What is the fuel psi swing fluctuation with the vacuum line to the regulator connected and disconnected?

ECM also looks to be MEFI 3 using TB-V distributor as AD mentioned...So those engines did use the lower 30 psi fuel regulator.

By chance with this engine model, is there any quick bouncing/fluctuation seen in the fuel pressure gauge while running?

Using a engine vacuum gauge, You may want to check what the engine vacuum is doing to see if it's within normal ranges with no real fluctuation going on....Maybe an internal valve problem.

Merc injector part number 861260T = Magneti-Marelli injectors which were used on some small blocks (and some big blocks) which is shown rated at 30 psi for the small blocks and 43 psi for some big blocks.

 

[alldodge]

FT, just tried to send you an PM and there was no send button. No secret but does side track a bit on the thread.

How can I/we get some of the info you can locate? We have the basics but all the one off differences makes it ruff to help. There is another thread going on where the guy has 1 beep per minute (cat motor) and I can find nothing which there even would be a 1 beep.

The first s/n range for 6.2 shows the FP reg in question. If we look at the second s/n range there is another p/n and does list 43 psi

Anyway a cheat sheet can be found?

 

[Ceboyett]

Guys i aprraciate ALLLLLLL the input! They problem was found! The number 6 injector was shorted! Replaced it too runs like a champ!

 

[Ceboyett]

Thanks guys for ALLLLLLLL the help! Found the problem! #6 injector was shorted messing up all the others. Changed it out runs like a new one!

 

[Ceboyett]

Thanks guys for ALLLLLL the help! I figured it out. #6 injector was shorted causing the others not to fire right. Swapped it out runs like a champ!

 

[Fun Times]

FT, just tried to send you an PM and there was no send button. No secret but does side track a bit on the thread.

How can I/we get some of the info you can locate? We have the basics but all the one off differences makes it ruff to help. There is another thread going on where the guy has 1 beep per minute (cat motor) and I can find nothing which there even would be a 1 beep.

The first s/n range for 6.2 shows the FP reg in question. If we look at the second s/n range there is another p/n and does list 43 psi

Anyway a cheat sheet can be found?

Unfortunately something's amiss with the Message system again as I can't even read them unless I use the recently discovered work around from the last time some of us couldn't open the PM's, etc..

Here's the work around link if needed, https://forums.iboats.com/privatemessage/notification

Truthfully a lot of the differences I bring up for the newer MPI stuff is just stemming from memory of the changes that were to be coming over the years before leaving the marine business professionally plus using that experience, I'll try to search things out to try and help better where possible.

For the older stuff I have an old August 2007 Merc marine tech handbook to look up things like the injector names I used above, the regulator part numbers vs what PSI they should be and what the color markings on the regulator means as in what PSI the color means...Pink = 30 psi which is the part number we all listed above.

I have noticed with Bam Marine ever since they switched their parts catalog around to a newer system a few years ago now, the serial number search feature seems to be a 60/40 spit if your going to get the right serial number range, right engine model listed for the true engine type the serial number actually belongs to such as some will show with 555 ECM type engines, the 5.0 MPI, 350 MPI, 6.2, MPI...Yes they may all use the same parts catalog but it will tell you you're looking up a 6.2 engine model but in all actuality the serial number belongs to a 5.0 when searched out someplace else.

Ceboyett, it's good to hear you located the issue being a fuel injector on number 6 cylinder...what prompted you to check the fuel injectors over?

 

[Ceboyett]

Fun Times.... i had a bad miss and fuel pressure was at 30 not at 26 as required. The 1,7, 4 and 6 injectors didnt sound right. So i started to pull them to pinpoint the miss. As soon as i pulled the #6 she started running right ( less the miss of that cylinder)