Engine quits when throttle up

gene8084 · Oct 4, 2009

Mercruiser 888, I/O, Ford 302, 2 bbl Holley, 30 gallon fixed Alluminum tank

She's was running just fine last time out. Starting (usually takes 2-3 attempts to idle and warm up), accelerating fine, & WOT 3800-4000 RPMs without a skip.

Today, took a few more attempts to getting idling at the Ramp, so I was patient and let her get to 120 degrees before backing away from the ramp.

When I shifted to forward she quit.
Started an tried a few more times. (quit, quit, quit)
Started and throttled up to about 1800 RPM's in neutral and tried to hold it there to burn what ever was happening out, but she quit.
Note, all the time sounding good/normal/smooth.
Started and tried reverse, quit.
In all cases I could idle (600 RPM +/-)

Flagged down a passing sailboat under engine power that towed me up river as far as close to the ramp as he'd dare. Then I was handed off to a nice guy and his family on a Grady White. (Good samaritans!)

I rebuilt the carb two full seasons ago and had two nearly perfect seasons until today. I also drained the tank at the same time. No way to really clean it, but emptied everything I could through the sending unit opening.

I've yet to pull the bowl or fuel water separator to examine the contents. I'm guessing I'm plugged up with something from the 35 year old tank.

Before I do....

Please tell me where you'd suggest starting. I hate to do a full carb rebuild again (adjusting was not trivial), but if that's the recommendation that's what I'll do.

Thanks

Don S · Oct 4, 2009

Re: Engine quits when throttle up

You need a new lower shift cable. The one between the engine and the drive. It's binding and holding the shift interrupt system engaged for too long.
Happens all the time, those cables are a maintenance item.

gene8084 · Oct 4, 2009

Re: Engine quits when throttle up

Jeez, hadn't thought of that, but the cable was replaced just before I got the boat. I could see it was new when I replace the bellows.

How do we explain dying when in neutral at higher than idle RPMs?

Apollo75 · Oct 4, 2009

Re: Engine quits when throttle up

gene8084 said:
Jeez, hadn't thought of that, but the cable was replaced just before I got the boat. I could see it was new when I replace the bellows.

How do we explain dying when in neutral at higher than idle RPMs?

I would check the distributor out --- run a point file through the points and check the cam lube, also lube the advance weights.

Could be a lot of things --- probably one simple one.

Mine did the same thing -- once --- the same animal too --- dirty points were to blame.

OFM

gene8084 · Oct 4, 2009

Re: Engine quits when throttle up

Apollo75 said:
1. ...point file through the points
2. ...check the cam lube
3. ...lube the advance weights

1. no problem.
2. how do I check the cam lube?
3. how do I lube the advance weights (u mean in the distributor?) and what kind of lube?

Hope it's one simple thing

Apollo75 · Oct 4, 2009

Re: Engine quits when throttle up

gene8084 said:
1. no problem.
2. how do I check the cam lube?
3. how do I lube the advance weights (u mean in the distributor?) and what kind of lube?

Hope it's one simple thing

LOL

Added : At myself ; I always think I am talking to other mechanics , my son says "Pops what the 'ell are you talking about."

The cam in the distributor that opens the points ---> needs a little grease or the point rubbing block will wear and the points will not open ---> lithium or what ever you have in the grease gun.

My distributor is a Mercruiser I think ---> been a long time

---> I remove the breaker plate with two screws and the advance weights are below. A little grease on the weight pins and on the spring lugs, and under the weights where they rub. The whole upper shaft area moves to advance the cam ---> a little felt pad in the shaft under the rotor lubes this upper part and needs some oil too.

Not much to these old ones.

OFM

bruceb58 · Oct 5, 2009

Re: Engine quits when throttle up

gene8084 said:
1. no problem.
2. how do I check the cam lube?
3. how do I lube the advance weights (u mean in the distributor?) and what kind of lube?

Hope it's one simple thing

Not likely the points but not a bad idea doing a tuneup and checking your dwell and timing if this hasn't been done in awhile.

Why not go down the path and check out what DonS suggested? Its a pretty easy test. Just remove the spark interrupt switch and see if it works? You may not be able to get the boat out of gear very easy but you will know your answer right away!

gene8084 · Oct 5, 2009

Re: Engine quits when throttle up

bruceb58 said:
Not likely the points but not a bad idea doing a tuneup and checking your dwell and timing if this hasn't been done in awhile.

bruceb58 said:
Why not go down the path and check out what DonS suggested? Its a pretty easy test. Just remove the spark interrupt switch and see if it works? You may not be able to get the boat out of gear very easy but you will know your answer right away!

Will do... easy enough.

I'll setup on the muffs, watch the switch, remove if required, and run and confirm dwell and timing.

My Q remains, why would it quit at 1800 RPM in neutral? The shift interrupt is not engaged in this mode. It behaves like it's out of gas after 4-6 seconds.

Back in a day or two with test results, truck into the shop today for tuneup and can't get the boat outside without it.

Bondo · Oct 5, 2009

Re: Engine quits when throttle up

My Q remains, why would it quit at 1800 RPM in neutral? The shift interrupt is not engaged in this mode. It behaves like it's out of gas after 4-6 seconds.

Ayuh,... 1 thing at a Time is how Diagnostics work,.....
It may, or may not be related...

Don S · Oct 5, 2009

Re: Engine quits when throttle up

While you are waiting for your truck, pull the fuel filter and examine it's contents. Under no circumstances reuse the filter, when you dump it, contaminants can get on the wrong side of the filter media and then on to your carb.
If there is a lot of water in it, you may have other things to do before test running again.

ziggy · Oct 5, 2009

Re: Engine quits when throttle up

besides the fuel/water filter, i'd think ya would have regular fuel filters too. ya might check them out too... i had crap in my fuel tank and the filters would plug up and cause me grief... R&R them and i'd be hip..

I'll setup on the muffs, watch the switch,

if i'm not mistaken, the interrupt switch don't work on the muffs. ya need to have a load on the prop for the interupt mechinism to activate the cam that operates the switch..

bruceb58 · Oct 5, 2009

Re: Engine quits when throttle up

ziggy said:
if i'm not mistaken, the interrupt switch don't work on the muffs. ya need to have a load on the prop for the interupt mechinism to activate the cam that operates the switch..

Its not supposed to work but it will if the lower cable is bad.

gene8084 · Oct 5, 2009

Re: Engine quits when throttle up

Don S said:
While you are waiting for your truck, pull the fuel filter and examine it's contents. Under no circumstances reuse the filter, when you dump it, contaminants can get on the wrong side of the filter media and then on to your carb.
If there is a lot of water in it, you may have other things to do before test running again.

Setup is tank, bowl, fuel/water separator, pump, carb. (no additional fuel filters)

I dumped the fuel from the bowl into a clear jar. ok, some very fine particulate, maybe slightly murky.
Fuel/water separator into a second clear jar, pretty much the same density, but 1/4" out of 3-1/2" settling on the top (assume that's water)
Replaced with new fuel filter
While I was there I examined the points. no sign of burning or black build up, almost like new. (replaced end of the 2007 season)

gene8084 · Oct 5, 2009

Re: Engine quits when throttle up

Bond-o said:
Ayuh,... 1 thing at a Time is how Diagnostics work,.....
It may, or may not be related...

I'm with ya...
One step at a time...

gene8084 · Oct 5, 2009

Re: Engine quits when throttle up

bruceb58 said:
Its not supposed to work but it will if the lower cable is bad.

Good to know, thanks.
If all else checks out and gets resolved and the interrupt appears not to be the problem, into the lake she goes to verify the interrupt.

bruceb58 · Oct 5, 2009

Re: Engine quits when throttle up

gene8084 said:
Setup is tank, bowl, fuel/water separator, pump, carb. (no additional fuel filters)

I dumped the fuel from the bowl into a clear jar. ok, some very fine particulate, maybe slightly murky.

Fuel/water separator into a second clear jar, pretty much the same density, but 1/4" out of 3-1/2" settling on the top (assume that's water)

Replaced with new fuel filter

While I was there I examined the points. no sign of burning or black build up, almost like new. (replaced end of the 2007 season)

That's a lot of water!

Bondo · Oct 6, 2009

Re: Engine quits when throttle up

Fuel/water separator into a second clear jar, pretty much the same density, but 1/4" out of 3-1/2" settling on the top (assume that's water)

Ayuh,.. Gas floats,+ Water sinks....

gene8084 · Oct 6, 2009

Re: Engine quits when throttle up

yup, pump and dump. I was shocked. She was drained two years ago. Stored in doors. So, the only way water could get in is the vent underway or during wash down.... unless it's coming from the pump at the station, doubt that.

Bondo · Oct 6, 2009

Re: Engine quits when throttle up

So, the only way water could get in is the vent underway or during wash down....

Ayuh,... I posted the Answer to that up in the boating forum where you posted the comment about it...

Don S · Oct 6, 2009

Re: Engine quits when throttle up

Fuel/water separator into a second clear jar, pretty much the same density, but 1/4" out of 3-1/2" settling on the top (assume that's water)

After finding 3 1/4" of water in the filter, I hope you pump the water out of the tank and clean out the hoses up to the filter, or you will have a brand new filter full of water again.
Here is a method to get the water out of the tank.
http://forums.iboats.com/showthread.php?t=212830

Engine quits when throttle up

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