Mercury 350 magnum problems please help

[tpenfield]

Usually the fuel lines past the tank pump are under pressure, not vacuum. So it would spit fuel, and you would certainly know about it.

Which Mercruiser manual is the right one for this engine?

You could try a full purge/cleaning of the fuel system from the tank to the injectors :noidea:

 

[alldodge]

What was the part number of the regulator you replaced and was it purchased from a Mercruiser dealer?

 

[tpenfield]

FWIW - I just replace the fuel pressure regulator on my 7.4 MPI (1996). Previously it was 28-30 psi versus a 34-38 psi spec. The new regulator brought the pressure into spec, but the but performance was not dramatically altered . . . as it as not running that badly with the out of spec pressure. I believe you had 30 psi vs the 36 psi spec. So, very similar to the condition that I was seeing on my engine. Not a day/night difference by any means, but nice to have back in spec.

 

[alldodge]

Just to clarify what I believe we are working on. In the first few post we were told it is a 1997 350 mag 300 HP MPI. Being that setup it should be the motor listed in the first column and the pressure should be 43 psi. If someone installed a different regulator the psi will be held at 30 psi.

Things that do not add up if one is 43 psi and the other is 30 psi:
Regulator for all TBI and MPI models are showing the same part number 807952A1

 

[badbowtie]

807952a 1 is the regulator that I bought from a merc dealer and the fuel cool assembly both from the dealer that is still working on the boat. Know they are thinking the electric circuit board and are trying to borrow one from someone. Yes you are correct it is a 97 350 mpi engine.

 

[badbowtie]

Okay yes it is also the first column and you are saying the 30 psi and 43 psi both call for the same regulator part number. Which I dont understand how that would work.

 

[badbowtie]

On another site I was just looking up regulator and it looks like I think I should of had 861126A 1 not the one I got.

 

[Fun Times]

S/N 0K163560 = 1997 MERCRUISER MPI, W/PS, TWO-PC-EX, WORO, GEN+ 350 MPI BRAVO Model number 4350118KS which uses the Intake Plenum And Flame Arrestor system. Here's is the complete parts guide through iboats, http://www.iboats.com/350-MAG-BRAVO-...iew_id.1692173

The service manual is confusing for sure showing the 350 MAG to be a 43 psi fuel regulator while all the parts guides show a 30 psi regulator.. Also looking up the regulators used in a service tech handbook, yours show it to be a 30 psi system. Below are all the ones close to your engine but you have to read them very closely as some are VST while others are Cool Fuel which you have the cool fuel system and GEN+.

• MEFI-1, -2, -3 ECM Fuel Regulator Identification - Contd. Engine Color, System Regulator, Model, Code, psi (kPa), P/N, Comments,
V8 5.7L, MEFI-1, (MPI, Cool Fuel on Port side, Gen+ engines, Keihin injectors). 350 Mag MPI Pink = 30 psi (207) 807952A 1 Regulator on fuel cooler. No ring on hose, Bravo, Inbrd, Ski, fitting. Black Scorpion Ski.

V8 5.7L, 6.2L, MEFI-2, -3, (MPI, Cool Fuel on Port side, Gen+ engines, Magneti-Marelli injectors). 350 Mag MPI Pink 30 psi (207) 807952A 1 Regulator on fuel cooler. No ring on hose Alpha, Bravo, fitting. Inbrd, Ski, and MX 6.2 MPI Bravo, Inbrd.

V8 5.7L, MEFI-1, (MPI, VST, Non-Gen+ engines, Keihin injectors). 350 Mag MPI Unknown color, 43 psi (296) 806808A 2 Regulator on the fuel rail. Bravo, Ski.

V8 5.7L, MEFI-1, (MPI, VST, Gen+ engines, Keihin injectors). 350 Mag MPI Unknown color 43 psi (296) 806808A 2 Regulator on fuel rail. Bravo.

Fuel Injector Identification (Revised Aug. 6, 2004)
V8 5.7L, MEFI-1, (MPI, VST, Non-Gen+). 350 Mag MPI Orange Tip 43 psi (296) 806807A 1 [Keihin]. Bravo, Ski.
V8 5.7L, MEFI-1, (MPI, VST, Gen+). 350 Mag MPI Orange Tip 43 psi (296) 806807A 1 [Keihin]. Bravo.
V8 5.7L, 6.2L, MEFI-1, -3, (MPI, Cool Fuel on Port side, Gen+). 350 Mag MPI White Tip 30 psi (207) 805225A 1 [Keihin]. Bravo, Inbrd, Ski, Black Scorpion Ski (5.7L & 6.2L), 377 Scorpion Bravo & Ski.
V8 5.7L, 6.2L, MEFI-2, -3, (MPI, Cool Fuel on Port side, Gen+). 350 Mag MPI None 30 psi (207) 861260T [Magneti-Marelli]. Alpha, Bravo, Inbrd, Ski, and MX 6.2 MPI Bravo, Inboard.

And while I'm in there tpenfield, here was yours too,
7.4L, 8.2L, MEFI-1, (MPI, VST and Cool Fuel, MerCruiser MPI intake). All 7.4L & 8.2L White Tip 36 psi (248) 805225A 1 [Keihin injector brand]. MPI models.

SB 97-20: Required fuel line replacement on Cool Fuel models. This effects a massive number of 1997 and 1998 models. The fuel lines may fail, causing a high pressure fuel leak or may collapse internally causing low fuel pressure above approximately 2800-3500 rpm. EFI and MPI Fuel Line Replacement

Sorry, guess I should have mentioned earlier that if the engine is running then the pickup coil under the rotor is working as the pickup coil wouldn't reduce power to 3500 RPM....The engine wouldn't flat out run at all....But yes the EST control module just under the dizzy cap could hold you down from full throttle as it could/may not allow full ignition timing to advance fully so yes that was for sure worth a try specially being a MEFI 1 or possibly 2. MEFI 3 is a bit different for timing control.

 

[tpenfield]

:thumb: Fun Times

So, 807952A1 is the correct regulator for the OP's (friend's) engine. . . and it regulates at 30 psi. Which Merc manual is the one for this engine?

 

[badbowtie]

I am heading to the marine shop in a couple minutes with the owner because everything that chart shows it couple post ago shows I need the 43 psi regulator and the part number they gave me was the 30.

 

[tpenfield]

I am heading to the marine shop in a couple minutes with the owner because everything that chart shows it couple post ago shows I need the 43 psi regulator and the part number they gave me was the 30.

Based on the info that Fun Times posted, it looks like your engine IS the 30 psi, because it is Gen+ and Cool Fuel (not the VST) that is noted. The chart in the manual that is a few posts back seems to contradict other info in the manual as well as the parts diagram for your engine. :noidea:

 

[badbowtie]

Yea if you look up part by serial number it calls for the 30 psi one but then if you look at that chart it says 43 and if you look up both regulators from another site it says this. So that description tells me we need the second one. So do what info do they have wrong I am thinking if you look up serial number is were they have it listed wrong but not sure.

REGULATOR MOUNTED ON FUEL COOLER. PINK COLOR MARK. FITS MCM/MIE GM V-6 & V-8 (305, 350, 377) EFI ENGINES & MCM 575 SCi. 807952A 1

REGULATOR MOUNTED ON FUEL COOLER. BROWN AND BLUE/GREEN COLOR MARK ON BASE OF TUBE. FITS MCM/MIE 4.3L MPI, 5.0L MPI, 350 MAG MPI & MX 6.2L MPI ENGINES WITH ECM 555 AND MCM/MIE 7.4L MPI (L29), 454 MAG MPI, 496 MAG & HO, 500 EFI AND MIE 8.1S & HO. 861126A 1

 

[tpenfield]

No harm ( that I am aware of) in trying the other regulator to see if the higher pressure.

I still would run a very high concentrate of injector cleaner thru the fuel system.

 

[Fun Times]

REGULATOR MOUNTED ON FUEL COOLER. BROWN AND BLUE/GREEN COLOR MARK ON BASE OF TUBE. FITS MCM/MIE 4.3L MPI, 5.0L MPI, 350 MAG MPI & MX 6.2L MPI ENGINES WITH ECM 555 AND MCM/MIE 7.4L MPI (L29), 454 MAG MPI, 496 MAG & HO, 500 EFI AND MIE 8.1S & HO. 861126A 1 [/COLOR][/FONT][/FONT]

That's where you have to read them carefully....The 43 psi regulator is said to be for the newer engine models that uses a 555 ECM...Your ECM is MEFI 1 or possibly 2.

AD has the correct manual shown 90‑823225‑190‑823225‑1

Found some info covering the 1998 350 MAG MPI engine model and is said to run 30 psi as well...List below.

Engine Specification
Models: 1998 MCM 350 Mag MPI Alpha and Bravo, MIE 350 Mag MPI Ski, MIE 350 Mag MPI Inboard.
Engine Propshaft Power 300 hp (224 Kw) Displacement 350 cid (5.7L) Engine Type / Rotation V8 Gen+ / LH Bore x Stroke 4.00 in. x 3.48 in. (101.6 mm x 88.4 mm) Compression Ratio 9.4:1 Compression Pressure Minimum 100 psi (690 kPa) Oil Pressure @ 2000 RPM Minimum 30 psi ( 207 kPa) Oil Pressure @ idle RPM Minimum 4 psi (30 kPa) Valve Adjustment/Lifter 1 Turn Down From ?0? Lash / Roller Thermostat 160? F (71? C)
Ignition Type of Ignition System Delco EST Firing Order 1-8-4-3-6-5-7-2 Spark Plug Type Original: AC-MR43LTS Others: NGK BPR6EFS, Champion RS12YC Spark Plug Gap .045 in. (1.1 mm) Initial Ignition Timing 8? BTDC at Idle RPM
Electrical Alternator 65 amps Battery Required Minimum 550 cca or 700 mca (120 Ah), 12v Negative (-) Ground
Fuel Type of Fuel System Multi Port Fuel Injection with Electric Fuel Pump Fuel Required Minimum 87 Octane [R+M/2] / (90 RON) Fuel Pressure 30 psi (207 kPa)
RPM Idle RPM 600 RPM Full Throttle RPM Alpha, Bravo, Ski: 4600-5000 RPM, Inboard: 4400-4800 RPM
Carburetor Preliminary Idle Mixture N/A Float Level N/A Float Drop N/A Choke Unloader/Pull-Off N/A Choke Setting N/A
Capacities Oil Change with Filter Approx. 5-1/2 US Qts. (5.2L) Closed Cooling System 14-1/2 US Qts. (13.7L) Sterndrive Gear Lube Same as Before MIE Transmission Same as Before MCM BlackTrac Approx. 2 US Qts. (1.9L)
Torques Exhaust Manifold or Elbow 25 lb. ft. (34 N?m) Intake Manifold 132 lb. in. (15 N?m) Cylinder Head See Service Manual #17 Flywheel 75 lb. ft. (100 N?m) Flywheel Coupler/Driveplate 35 lb. ft. (48 N?m)

 

[tpenfield]

badbowtie - any updates on this? I'd be interested to know how it turned out?