Rochester 2bbl carb

[stratmagic]

Fixed - sort of

Fixed - sort of

Tore the carb back down and reset the float - that seems to have fixed the running rough problem. However, the engine still has trouble around 2000 rpm.

The engine starts almost instantly, runs great at idle, and runs great at 2500-3000 rpm. However, the transistion from idle to full speed is rough. If I try to set the throttle to 2000 rpm, the engine either bogs down and the RPM's drop - or it surges up to 3000.

I'm assuming that there is something wrong with the mid circuit in the carb. The engine acually did this before I rebuilt the carb so maybe there is something wrong in the carb that I missed or that the rebuild kit didn't cover. Any suggestions on what to look at next?

I will say the engine starts a 1000 times better after the rebuild. Just breathe on the ignition and the engine fires right up, even after it's been sitting over night.

I appreciate all of the suggestions and the re-build wasn't nearly as difficult as I anticipated.

 

[Willyclay]

Re: Rochester 2bbl carb

Since Don S has not jumped in to help you, looks like you are stuck with us "non-experts"! Did your rebuild kit come with a new Main Jet? If not, did you visually verify the old jet was clear by blowing compressed air through it after soaking and/or passing something like weedwacker line through it?

Additionally, since you now say the problem is occuring during throttle transition, did your rebuild kit come with a new Power Valve and Power Valve Plunger? If not, this may be a problem area to work on.

Also, as another poster already suggested, your ignition needs to be right. I had the personal experience of spending a long day in the ICW because of a weak/bad coil on an inboard engine. It started and idled great, but fell flat and ran real bad at anything above 1,500 RPM.

Finally, any chance you have bad gas? Can you put fresh gas in a remote/outboard tank and try that just to be sure?

We'll keep trying as long as you are willing! Good luck.

 

[Willyclay]

Re: Rochester 2bbl carb

Glad to hear you are making good progress. I was typing as you were posting so some of my latest post does not apply. Thanks for keeping us updated.

 

[boaty89]

Re: Rochester 2bbl carb

can anyone tell me why i have to clamp the rubber line coming from the fuel pump to the back of the carb in order for it to run?

 

[Jeepster04]

Re: Rochester 2bbl carb

can anyone tell me why i have to clamp the rubber line coming from the fuel pump to the back of the carb in order for it to run?

Incase the fuel pump goes bad the gas will go into the carb. Its a vent for the fuel pump.

Don S, Im confused why you say the info is scary but you didnt say why or help anyone?

 

[boaty89]

Re: Rochester 2bbl carb

thanks for your reply jeepster04, is it normal for fuel to be spitting from this hose with the engine running? the engine will be running perfect and as soon as you pull the clamp off the engine dies

 

[supercab78]

Re: Rochester 2bbl carb

If you are talking about the small hose that goes to the top of the carb. NO there sould NOT be any gas coming out of it! This means that one of the diaphrams in the fuel pump is leaking some fuel. This is DANGEROUS !! The small hose leaking out fuel is a taletell sign of the pump going bad. As the hole gets bigger in it will leak more and eventually float out the carb. so it no longer runs. Kind of a safty function. A car fuel pump would just pump it out onto the road or engine and maybe catch fire.

 

[Jeepster04]

Re: Rochester 2bbl carb

thanks for your reply jeepster04, is it normal for fuel to be spitting from this hose with the engine running? the engine will be running perfect and as soon as you pull the clamp off the engine dies

Nope, thats not normal. That usually tells you that the fuel pump is bad or is going bad. If it wont run without that hose pumping gas into the engine then the pump isnt giving the engine enough gas. Not a real expensive part to replace.

 

[Bondo]

Re: Rochester 2bbl carb

can anyone tell me why i have to clamp the rubber line coming from the fuel pump to the back of the carb in order for it to run?

Ayuh,... Welcome Aboard Boaty,...

This thread is a Year old,+ is about Somebodyelse's boat....
Start Your Own thread,+ tell Us about Your Boat,+ it's Problems....

 

[boaty89]

Re: Rochester 2bbl carb

thanks for your help, i'll take care of that problem as soon as possible. that probably explains the trouble i was having yesterday when i got the boat out for the first time after rebuilding the engine. thanks again.

 

[boaty89]

Re: Rochester 2bbl carb

thanks for the reply, will repair as soon as possible

 

[boaty89]

Re: Rochester 2bbl carb

how do i start a new thread? i need all the help i can get!

 

[jtybt]

Re: Rochester 2bbl carb

boaty,
you probably have a ruptured diaphram in the fuel pump.

 

[boaty89]

Re: Rochester 2bbl carb

maybe you can help me with this one. sitting in the driveway with water hooked to it the motor runs fine, once it's in the water it's hard to start, runs rough and it won't idle. any ideas?

 

[boaty89]

Re: Rochester 2bbl carb

Does anybody read these anymore?

 

[Mr Wubbs]

Re: Rochester 2bbl carb

I have 87 OMC 140 with a Rochester 2 GC. The carb was rebuilt as well as the motor by a very good shop. I am having issues with the motor idle being very rough at times and hesitation as you increase RPM. I am also seeing the plugs are getting black fouled.
The motor starts up on click.............does not stall.

I have checked all ignition and wiring, pumped all gas from tank and installed new fuel pump and filters.

I have taken the boat out and it cannot run for more than 1 hour without coming to a stop.

ANY IDEAS ?

 

[Don S]

Re: Rochester 2bbl carb

IF you have a question, start a new thread. Don't just tack on to some old thead and hope your question gets noticed.
This thread is from 2008 and about a Mercruiser carb, you have an OMC.