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View Full Version : '94 22 classic 454 mercruiser engine trouble



jeffaf
07-26-2005, 06:19 PM
Well the Mercruiser dealer has tried everything except taking the engine apart. The engine starts and goes into gear but does fire on all cylinders. 2 on each side do not fire. Tried fuel pump, distributor, throttle cables, etc. Nothing.

The mechanic now wants to get into the engine and try the cams.

This is the strangest thing. Could it have been caused by the gear lube running low or out while at high RPMs? Anyone else run into this?

Anyone had to replace any engine before? Lot's of questions but we've only owned the boat since last October.

Any advice would be greatly appreciated.

Thank you.

gold-n-rod
07-26-2005, 07:04 PM
Wait.. Your saying two cylinders on each bank go dead when it is put into gear, but they are fine in neutral??

Here's a SWAG: bad shift interrupter?

mphatc
07-26-2005, 07:13 PM
We need some more info here after an
answer to Poodle's question and to Gold-n-rod's . . .



compression on all cylinders

condition of plug wires, spark plugs, distributor cap, all items in secondary circuit for those two cylinders

Before going into the engine . . alot can be learned from the above

Mario

gold-n-rod
07-26-2005, 07:19 PM
Here's a SWAG: bad shift interrupter?

On second thought, a '94 454 should come with a Bravo drive. Bravos don't have a shift interrupter, do they? Only Alphas, IIRC.

Can't really fix a problem by throwing parts at it. $$$$$$$$$$$$$$$$ :eek!:

gold-n-rod
07-26-2005, 07:21 PM
More thoughts: Has the ignition been completely checked out? Yes, you said new distributor, but what about the amplifier and its ground. Plug wires???? I've been through both in a similar powertrain of similar age.

Me thinks you need a different mechanic.

gold-n-rod
07-26-2005, 07:24 PM
"cams" is scary :eek: :eek:

Maybe it's one of those rare DOHC big blocks!!!!!!!!!!!!!!!!!!!

BUIZILLA
07-26-2005, 07:53 PM
'bout the next thing to replace, would be the mechanic.

JH

Rootsy
07-27-2005, 12:59 PM
the word "mechanic" shouldn't even be associated with a hack like that http://www.donzi.net/forums/images/smilies/puke.gif

gee wonder if he checked to see if the throttle cable was moving with the throttle lever stroke and if it was moving the throttle shaft in the carb?

blackhawk
07-27-2005, 01:53 PM
Figured I'd reply to both of your posts.

Talking out my azz here BUT it's a thought!

You said this happened the same day you noticed the drive reservoir was empty. There is a "float" inside there hooked to a sensor. When the reservoir gets low your boat will go into limp mode. It is very possible that this float stuck even though you filled the reservoir.

I would check that asap!!!

gold-n-rod
07-27-2005, 04:55 PM
When :confused: did he say the drive reservoir was mt?

1st post: "This is the strangest thing. Could it have been caused by the gear lube running low or out while at high RPMs? Anyone else run into this?"

I'll be the first to admit that I didn't know about the safety feature referred to by Blackhawk. I honestly don't think the engine management system on a '94 is that sophisticated, but I've been wrong before......... just ask my wife! :biggrin:

jeffaf
07-27-2005, 09:14 PM
Wait.. Your saying two cylinders on each bank go dead when it is put into gear, but they are fine in neutral??

The cylinders don't fire at all. The boat starts but only fires on 4 cylinders.

We're picking the boat up tommorrow and taking it to a different marina. I'll give more details tomorrow afer we meet with the "mechanic". I'l be able to tell you exactly what they tried.

Does anyone know if the '94 mercruiser bravo one has the "float" sensor in the reservoir that blackhawk is referring to?

Thanks for all the responses. Every time I come to this web-site and see the photos of all of your boats I get jelous and pissed-off. I want to get back on the water!

blackhawk
07-27-2005, 10:08 PM
Is it only idling on 4 cylinders as well? :confused:

Unhook the reservior and clean it out(good idea anyway) and make sure the float is sliding up and down.

I have no idea how the limp mode works, if it cuts out cylinders or not. But I know it limits the rpm to 2500(or close). Like I said, I'd be checking that ASAP.

Remember, always start off with the simple chit first! :yes:

Pismo
07-31-2005, 05:47 PM
Limp home mode limits RPMs, it doesn't turn off random cylinders. Electrical. Compression test would be nice to eliminate many major problems.

BUIZILLA
07-31-2005, 07:41 PM
Is this a carbed engine or EFI/MPI ?? why did the guy change the fuel pump ?? if it's carbed, did he change the coil ??

Dave_N
07-31-2005, 08:11 PM
As a few others mentioned, pre 1996 models have a "Power Reduction Mode" that cuts out half of the fuel injectors when one of the "discrete switchs" (gear lube level being one of them) detects a problem.

Seems very likely that you are in Power Reduction Mode due to stuck or bad gear lube level switch.

However, a bad injector driver circuit will have the same effect (lose two cylinders on either side).

Dave