2002 hammerhead 350 help and info please

[Woodski]

@ubugarrity:  That engine in good health will provide 400 hp, why are you indicating you need 400 hp?  I suggest you determine at least closer to the root cause as to why it is not running well.  Whether it is a 350 or 383 short block, the fuel delivery and spark are tuned to the cylinder heads and camshaft they don't care much about the actual difference in displacement at least in the macro sense.  There is a reasonable probability your issue is spark or fuel related which has nothing to do with the long block parts.  As noted previously, I would do a compression and leak down test to see if there is an issue with those components.  I would also rotate the engine to verify the cam lobes are in good shape, make sure the distributor spins and is oriented correctly.  Cleaning the fuel system is also a good step.  My comments are directed at basic troubleshooting without any real understanding to what the problem is as you only indicate it runs terrible which is not much to go by, a detailed description would be helpful for any productive advice.  All the items I have noted are cheap to do, just trying to save you from buying or doing something expensive you may not need.

 

[ubugarrity]

UPDATE: I finally got this boat at my garage to check it out first hand. This is on the trailer:

Turned key and it started right up and ran smoothly. After about 10 seconds just stopped. Turned key, starts right back up and smooth. Did this several times. I installed a fuel pressure gauge just to rule out fuel supply at rails. I think pressure was 40-50 and steady, no leak down. 

So I started checking sensors and wire connections. While engine is getting warmer, it wasn't stalling but the idle was all over the place. (Tach not working so I'll have to fool with Medallion at a later time). I checked TPS  and seamed good. Started Engine and with it idling all over the place I disconnected TPS. The fault beeping started and idle smoothed out. I'm assuming the MEFI sensed a fault and went into a default value mode. Engine ran for a while very smooth, even at acceleration. As soon as you plug TPS back in idle goes all over again. Also, when I say the idle varies, that's all that is happening. The engine never runs "rough" like a sputter or backfire. 

If anyone has any ideas what I can check, please let me know. I'm gonna fool with it again this afternoon. 

If the MEFI is for a 5.7 liter with different cam and heads, and you switch the block out to a Standard 5.7, would the MEFI cause this problem?

Thanks for help!

 

[Woodski]

@ubugarrity:  Sounds like an IAC (idle air control) issue.

[boardjnky4]

38 minutes ago, Woodski said:

@ubugarrity:  Sounds like an IAC (idle air control) issue.

agreed

[ubugarrity]

The IAC was next on my list to check.

I had opened engine cover this morning. The engine was baking in the sun for a couple hours before I got to work on it. I started the engine to warm it up as per diagnostics and it ran smooth for 20 minutes. Figures. I still suspect the IAC. I wish I could confirm the part number but I might just go get one anyway. It would be too good to be true if this works.

 

[williemon]

Just throwing 2 cents into the mixture. Wouldn't the mefi be basically standard from motor to motor, and the ECM control the pulse width and duty cycle of the injectors? At any rate, Im glad you are working on diagnosing the actual issue. Im going to assume that neither the IAC nor the TPS has been changed. I would not know how to check them,  but the troubleshooting you have just done sounds better than saying the engine needs to be changed. I will also assume that any computer related controls, sensors, timing, EFI need to be tuned to what ever heads and cam you are using for max efficiency. 

[ubugarrity]

This morning, I just keeps stalling. I've changed nothing. It will start right back up. I've checked the IAC as per diagnostic test and it shows fine. I replaced the TPS and it seems to have no effect. (engine runs good or bad regardless of which TPS is in) Again, If I disconnect the TPS engine shows DTC and runs fine. I reconnect the TPS and as soon as the DTC clears, engine will surge and stall. 

It was cooler out this morning so I figured I'd check the ECT. As per diagnostics, ohms in sensor are normal and voltage to sensor are normal. I disconnected it while running to cause a DTC. No noticeable difference in engine running. Now I can't clear DTC 14. Any ideas on this? I tried normal service mode, throttle up and back, normal mode, engine off 20 sec. When I check it still has DTC 14. I even disconnected battery for 10 minutes. no different. Very frustrated

[ubugarrity]

I changed TPS and IAC. No luck. actually just keeps stalling now. I've gone through everything I can. To recap, the engine is supposed to be a Hammerhead 365. This is a standard GM 350 block with GM Performance "Fast Burn" aluminum heads and the cam is a GM P/N 10185071. IF a regular 350 block was put in, should the MEFI 4 run the engine or are they that specific?

What is this boat worth as is? make offer!

I'm voting  to pulling this engine out and replacing it with https://blueprintengines.com/collections/marine-engines/products/marine-383-1

Desperate to get a boat on the water. 

[Woodski]

@ubugarrity:  I am not exactly sure on the MEFI matchup as I am not sure on the fueling system you have. 

I have pretty much that same setup, although carbureted, on my Echelon and it is a rocket and in that Flightcraft it should amazing.  I don't think your block or heads are an issue it is probably all in the FI unit and the signals to from ignition and fuel system to the MEFI or a sensor issue.  What distributor setup do you have?  Mine is a Merc Thundervolt IV.  If mine, and I could not diagnose the ignition / fuel issues, you might consider going simple and installing an Edelbrock Performance RPM intake manifold coupled to an Edelbrock 1410 carb if you are considering a complete engine swap unless there is something else amiss with the long block.  Edit:  I see from the link you are considering a carbed solution, doing from intake up would be much cheaper than a complete swap.

Edited June 18, 2018 by Woodski

[boardjnky4]

I'd probably try replacing the MEFI computer before messing with swapping the entire engine out.

[Gary Pelletier]

I have a 2002 Response Barefooter with the “350” Hammerhead. Motor failed 2 yrs ago - heads corroded out, aluminum heads on cast block with no closed cooling is a ad design.  Anyway - replaced with a brand new GM Marine Long Block, kept all the bolts ons,  reprogramed the ECU and the boat has run awesome since.  PM me if you’d like more info...

[ubugarrity]

Vacuum gauge would be in the green, then start to wobble, then drop. The engine seemed to be following the gauge and not the other way around. (Vacuum would drop and engine will follow till stall). Took intake manifold off. 4 center bolts where loose. I'm guessing they didn't remove fuel rail to torque them. So new gaskets. Also read to seal around t-stat housing bolts as this would cause vacuum leak. I didn't think that was done but already had the parts cleaned. I did seal around them. Put everything back together and does the exact same thing. I'm completely frustrated and have to give up. Bringing it back to the team tomorrow morning. I would love to run into the dealer that sold us this crap. Anyway, I think the boat will be for sale. Northern NJ. Thanks for all the help. 

[Charlotte2]

On 23/06/2018 at 20:36, Gary Pelletier said:

J'ai un 2002 Response Barefooter avec le "350" Hammerhead. Le moteur est tombé en panne il y a 2 ans - têtes corrodées, têtes en aluminium sur bloc moulé sans refroidissement fermé est une conception publicitaire. Quoi qu'il en soit - remplacé par un tout nouveau bloc long GM Marine, gardé tous les boulons, reprogrammé l'ECU et le bateau a fonctionné à merveille depuis. MP moi si tu veux plus d'infos...

hello Gary, I am unhappy with my engine hammerhead...have told me that my ECM is not for a Hammerhead but for a monsoon2...
Can you confirm that hammerhead ECM is particular different from the other 350 Monsoon?
My ECM is an ECFI I have the delphi 16237019 below the bar code 867019KA00005989.

Thank you in advance for an answer that will help me a lot!!

[COOP]

@Engine Nut Is an Indmar tech. He should be able to shed some light on this.