Any Ideas?

[sausageman]

Ok! now I'm a tad frustrated. Anyone have any suggestions?
I have a 302 ford engine in a 1971 Searay SRV 240 with a mercruser outdrive. I can troll all day. The engine runs like a swiss watch, as soon as I try to throttle her up everything breaks down in the 1500 RPM range. I have completely replace the ignition system with a Mallory electronic system, thinking the failure was electrical but with the same result. If left in neutral the engine will turn 4000 RPM in a heartbeat without even a hick-up.
The shortblock is new and I've replaced everything but the carborator and this is my next target. Is it possible my carb is flooding out at higher throttle settings? How tough is a carb rebuild on a Holley 4 BBL? I'm open to any suggestions and appreciate any and all help offered.

[jpollman]

Greg,

we've got some good minds here. I'm sure someone will come up with something. But in the meantime, I'd post the same question over here :

http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=forum;f=24

You'll have to register to post. But it's free and easy. There is an absolute TON of information over there. It's a nationwide forum and have gotten some good information on my outboard. (But that's a separate forum) I believe the link I posted was to their I/O forum.

If I come up with any ideas, I'll post them here. Good luck !

[POLARBEAR]

maybe it is not getting enough gas. clogged filter, bad pump. good luck!:)

[Ed Michrina]

my boat did the same thing.
I found a fitting right at the gas tank. It has a spring and ball bearing inside the fitting. I guess it keeps pressure to your engine for easy starts. this fitting is before the gass filter. Well a little bit of plastic got caught up in the spring.
you should be able to run a new gas hose to a separate gas source with out filters ect. and give it a run.
Also Check your air intake for your gas tank. Spiders like to make nest in them and clog the screen. at rpm's could also do what you described.

[kroppe]

sausageman,

Just thinking out loud here. Maybe you have ignition wires that are arcing. I had a Mazda Miata that went through plug wires like crazy, and the symptoms were missing and misfire (big time) under any load more than idle. The observable issues with the Miata were hesitation, misfire and black smoke out the tail pipe. I didn't check this, but you probably could have seen arcing under the hood if you looked at night.

For the Miata, the fix was new plug wires, and the problem went completely away for 6 months, then it was back again at which time I fed it a new set of wires.

I know you just did some ignition work, maybe you have some arcing somewhere in the system.

[ESOX]

Sure sounds like a fuel delivery problem. I'd check the flow rate from the pump before getting into any Carb work. Also a lot of Holleys have a small screen filter at the carb, right where the fuel line attaches. I have found many of those clogged, despite there being an in line filter.

[Gone Fishing]

I kind of have a hunch that Ed Michrina is on the right track. Those anti siphon valves have caused plenty of headaches. Some of them are take apart units so you could try removing the spring and ball as a quick test.

[Heavy duty]

everything breaks down in the 1500 RPM range

Breaks down as in flooding or running lean??

If your flooding it's easy to see. Start the boat let it warm up a bit. bring RPMs up around 2500. while looking down the carb shut the boat off. If gas keeps pouring down the throat then you may be due for a rebuild??


If you take the carb off your self and have shop rebuild it for you it's alot cheaper. I paid $140 last year. There are some internal setting that need to be right the first time. No way to tweek them in while the boat is running.

[Shoeman]

Have you checked for moisture in the distributor cap?
I know you replaced the system, but sometimes the gasket at the base may have been damaged during installation.

My 351 was famous for that. Condensation would build up and it wouldn't run under load.

Also check to see if the spark advance is working properly. Once the heat of the motor expands the metals, the plate may bind and not allow advance.
You can check that with a timing light.

[FishTales]

I had a similar problem with my '86 Crestliner, it would idle just fine and I could troll all day, when i tried to accelerate it would get up to about 3,000 rpm and before i could get up on plane it would bog down. I changed the water filter and same thing, then i changed the filter in the carb, it looks like a small bronze thimble, it was partially clogged and was blocking the gas flow. After changing the filter in the carb it ran ok.

[GOTCHA]

I know a great carb guy, if that's the problem, let me know, fair price to...

[Mad Jack]

Check the Distributor inside. My 89 Crestliner Saber Had a problem kinda like that.
it would troll pretty well but when you tried to take off it would spit and sputter at higher speeds.
It turned out to be a felt thing inside the Dist.
Now it runns pretty well.
Just something to check or double check.
Hope this helps.

[Banditto]

Just trying to clarify a little. When you say "breaks down" do you mean it stalls? or just sputters there and runs like crap.

One thing you can do when it is doing it is take a little spray bottle with gas in it (dangerous so don't leave it laying around) and spray a little bit straight into the carb. If it ramps up then you know for sure it is a fuel delivery problem.

And to verify if it is not spark (which it sounds like it is not) is take a timing light hooked up during your test run. If it starts to randomly cut out you need to look closer at spark. Being you just replaced your ignition system with a Mallory it probably isn't there, but rather in the power harness to your distributor. Start un-doing harness connectors and looking for green oxidation rot.

[bounty hunter]

my boat ran very good until I trolled for a few hours and it did the same as you are describing and I took it in for service and the problem was the carb. was dumping WAY too much fuel which fouled the plugs every time out..