Im back with my carb problems

[ProfitOfDoom]

I had a post before about my carb problems about it bogging down. I called today for the carb kit but they were out and had to order so im going to use tonight to make sure this is my problem. If anyone remember this post a good majority of people said it was my pump accelerator in the carb which you get in the rebuild,so does everyone still agree?
Since my last problems Ive cleaned my spark arrester,added soem lucas carb cleaner to the gas and ran all that out about 20 gallons,then added a higher grade of gas about 30 gallons and ran the better part of that out today,it did run smoother but still didnt eliminate my problem and I also replaced my water/fuel filter.
It seems my problem is when I try to push my throttle all the way it will go,,then bog down,go,bog,go,,,then bog and will continue untill you lower the throttle. On the ride home I couldnt get it over 25mph and about 3000/3200 rpm. If I try to get over that it would not take the gas and bog down,It never shut off on me,just didnt want to go.
I dont have a problem sitting at idle or running at low speed or shifting from forward to reverse,just when I try to push it.
I would think if it was a fuel pump I would have the problems more of the time?
Are we still confident the carb rebuild kit will solve this?
Is there anywhere online t order this kit cheaper,my local guy said the kit will cost $125.00
The car is a weber 4barrel on a mercruiser 454 mag bravo 3,the guy who sold me the boat told me the engine is a 99' but I gave the engine number that was on the plastic shroud thing that goes over the carb and he's saying its coming back a 92-94 model?
Does that sound right,$125 for a rebuild kit,I thought they were in the neiborhood of $50 to $75?

 

[Quint4]

I paid $130 for a rebuild kit for my weber. Have you put in new plugs? The 7.4 will eat them after many hard starts or if it has been flooded. It will run like crap. (NGK BR6FS)

 

[ProfitOfDoom]

No I havent done that,does that sound like that could be the cause from what I said about pushing it and problems when running it at or close to WOT? Or would it just run like crap all of the time if the plugs are bad?

 

[Quint4]

Mine would run okay at lower rpms with fouled plugs. May not be your entire problem but will make a big difference if you have a fouled plug or two. I would do the rebuild also...do you have a manual?

 

[ProfitOfDoom]

No, I don't have a carb manual but they say the rebuild kit should have directions . I hope it isn't that hard to do.

 

[83searay]

I pretty much have the same problem with my Mercruiser I/O 260 with a crate 350 motor I have done all of the above and then some, good luck when you find the problem LMK.

 

[OldSkool]

Posted from another thread.

I, like so many other, have experienced the dreaded power down after 30-45 minutes of tubing. It happened again this weekend.
I was pulling at 4800-5000 rpm when the throttle started backing off. It would only do about 3000 rpm (blower running the whole time).

We went into a cove and swam for an hour and a half then decide to tube some more. The first 20 minute went fine then it happened again. By chance my son opened the engine bay lid to look at the engine while we were running. It didn’t take more than a few seconds and the engine came alive. The thing shot to 5300 rpm like a rocket. It nearly yanked the person off the tube.

We ran with the cover up for a few minute then continued tubing for another 30 minutes with no problem. I looks like there is not enough air displacement in my engine bay. I thought it was fuel related but never considered air flow. Dah.:wow: I’ll need to increase the blower or add some type of better venting.

Going out again on the 5th so I’ll keep you posted.

Update.
I had no problem on the 5th.

 

[OldSkool]

I paid $130 for a rebuild kit for my weber. Have you put in new plugs? The 7.4 will eat them after many hard starts or if it has been flooded. It will run like crap. (NGK BR6FS)

I changed from Champion to AutoLite plugs. The Autolites will survive a flooding the Champions will not. I found this out after discovering my electric choke wire had come loose. She is carb'd.

 

[Quint4]

I do not use champions. Merc recommends NGK BR6FS (marine). Never tried Autolites although they are a lot cheaper.

 

[OldSkool]

I do not use champions. Merc recommends NGK BR6FS (marine). Never tried Autolites although they are a lot cheaper.

Due to my electric choke wire issue, I have flooded a few times since changing. I found this out by chance after not being able to find a champion plug I needed on a piece of equipment I was working on back in my field service day's. Put the AutoLite in and you could run fuel right over them, dry them off, and they would fire like new.

 

[chumbley]

The accelerator pump will appear as a bog when you accelerate quickly. If you do it slowly, the problems will be less noticable. If you cannot get to full RPM no matter what you do, then it probably isn't the accelerator pump. Not that it might not be bad, but if it tries, bogs, tries, bogs as you say, then there are likely other problems as well.

 

[Danny Troy]

Does that sound right,$125 for a rebuild kit,I thought they were in the neiborhood of $50 to $75?

The last 4-bbl carb I rebuilt was many years ago, and the kit probably cost $15.00! If you have never rebuilt a carb be very careful not to drop anything in the intake manifold. I believe I used to stuff a rag in the opening, just to play it safe. Rebuilding is not hard, but use a nice clean desk area and lay out the parts in the order they were removed. Also, if you have an ultrasonic cleaner that will help get the junk out of the small openings. I bought a nice unit from Harbor Freight for less than $55.00.

BTW, buying a rebuilt carb was always a good option, but I don't know if they are still available.

 

[ProfitOfDoom]

I could try to replace the plugs today, that will be easier than a carb rebuild. Chumbly mentioned that it is probally not the accelerator pump if I can't ease up the throttle to higher rpms. I could try to run hatch off and see if it's starving for air. But what else would make it do this?

 

[Quint4]

I would say a full tune-up is in order. Plugs,wires,cap,rotor and timing check.

 

[ProfitOfDoom]

The PO said plugs and wires were changed last season. I got back from the boat now and I pulled a few plugs they all were clean and had good spark. I asked the guy who worked down there if he knew any mechanics and he said not off hand,but he also mentioned that maybe the timing is off. How do I go about checking that?

 

[Quint4]

You need a timing light (gun) and a bit of know how. Have you pulled the cap and had a look at it? Maybe it is cracked or contains moisture. You can pay a mechanic to swap parts or do it yourself on the easy stuff. Is your gas tank vent line unobstructed as well as the anti-siphon valve on tank? The thing about a full tune up is it is not wasting money as it is probably needed and you establish a baseline of "good" parts on the system you are trouble shooting. I appears you have a fuel issue or ignition component problem. Replacing ignition parts is pretty cheap and may solve your problem. I would compression check that motor when you have the plugs out.

 

[ProfitOfDoom]

I will go check the cap now,Only thing I did notice was that on the cap there is this brass looking thing where it looks like its either a drain,or a hose should be connected,there is nothing there?

 

[chumbley]

Replacing ignition parts is never a bad idea - but if the plugs and wires were replaced last year - that is probably good enough. Changing the cap is not a bad idea, but it likely isn't going to cause the symptoms you are experiencing. Same with the timing.

I'm curious about this brass connector on the cap you are referring to. How about a picture of that?

This sounds like a fuel starvation problem to me. I believe the weber uses mechanical secondaries, and separate fuel circuits (floats, needle and seet, and all) for primaries and secondaries. If you have sufficient fuel pressure (check with a gauge) and you have changed the filters, then I would look closely at the carb itself, and ensure that there is fuel in the secondary bowls and that when you get into the secondaries they are indeed pulling fuel through the venturis.

 

[shore]

You have a little filter in the inlet of the carb.It gets clogged with sediment and does what you are describing.

It takes some patience to get the two nuts loose and it helps to have line wrenchs.They are a box end wrench with a cut out to get over the fuel line.Be very careful when putting the lines back together.They are brass and aluminum.They will crossthread.Put a new gasket on the carb filter if it leaks and do not over tighten.It;s soft metal.

Seriously, try this 1st.

 

[shore]

who told you it is a weber carb?

It is supposed to be a rochester quadrajet.

Make sure you are sure on this.