1995 mercruiser 4.3 starving for fuel

[sjm32157]

First trip to the river this year didn't go so well. Prepped the boat for the season as usual, test ran in the driveway on muffs for about 15 minutes, all was fine. after about 10 minutes of running fine at 3000 rpm, typical cruise, the engine starts popping, backfiring, and finally stalls. After I checked everything out, I was finally able to idle (500 - 700 rpm) back to the ramp. Replaced the engine 2 years ago with a Jasper long block. Ran great last year. Didn't replace the carb though. I did have a few flat spots when accelerating last year. Did I just wait too long to get the carb rebuilt?? Accelerator pumps shot? Are there any screens in the carb that could be blocked that I missed? I disconnected the supply line from the carb when I got home and turned it over a few times with the kill switch off. Got a nice "full pipe" of fuel. Any suggestions appreciated.

 

[tpenfield]

Re: 1995 mercruiser 4.3 starving for fuel

My suggestions would be to start with the fuel filter (replace) and then work your way to the carburetor (clean).. See how that goes, and follow up with some posts.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

I just finished swapping out the fuel/water sep filter. I emptied the contents of the filter into a clear jar and couldn't see any signs of water or trash. Think a dose of Berrymans would be worth a shot??? My carb probably is due for a rebuild I just never thought it would strangle the engine like it did.

 

[Deese566]

Re: 1995 mercruiser 4.3 starving for fuel

Hey buddy ,i'm gonna assume you gotta two barl mercarb on this eng . No there are no screens in this carburetor other than the screen cylinder shape fuel filter. It does sound like you're having some lean issues. Disassemble that carb an you'll likely find ya problem.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

No, it's a 4bbl. I never rebuilt a carb but I do have some local guys that specialize in cleaning and rebuilding so I think it's going to get pulled off of the motor and go for a trip. Like I mentioned before, I was amazed the effect it had on the motor, pretty much crippling it. probably a combination of dirt and wear.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

No, it's a 4bbl. I never rebuilt a carb but I do have some local guys that specialize in cleaning and rebuilding so I think it's going to get pulled off of the motor and go for a trip. Like I mentioned before, I was amazed the effect it had on the motor, pretty much crippling it. probably a combination of dirt and wear.

Checked vent line this morning, clear in both directions. Changed water sep filter, will run on muffs later. Is it possible the carb float is stuck in the up position closing the needle and restricting fuel flow? I know most of the float problems are from when they waterlog and hold the needle open making the engine run rich. I'll probably start shopping for a rebuilt carb but I'm running thru the "what ifs". Thanks for the info and suggestions. It's nice to have this forum when you are banging your head on the wall trying to solve a problem.

 

[Bondo]

Re: 1995 mercruiser 4.3 starving for fuel

No, it's a 4bbl. I never rebuilt a carb but I do have some local guys that specialize in cleaning and rebuilding so I think it's going to get pulled off of the motor and go for a trip. Like I mentioned before, I was amazed the effect it had on the motor, pretty much crippling it. probably a combination of dirt and wear.

Checked vent line this morning, clear in both directions. Changed water sep filter, will run on muffs later. Is it possible the carb float is stuck in the up position closing the needle and restricting fuel flow? I know most of the float problems are from when they waterlog and hold the needle open making the engine run rich. I'll probably start shopping for a rebuilt carb but I'm running thru the "what ifs". Thanks for the info and suggestions. It's nice to have this forum when you are banging your head on the wall trying to solve a problem.

Ayuh,.... Yer carb is a carbon copy of the Edlebrock Performer carb,...

Parts are Much easier to find for the Edlebrock, than the Merc parts, 'n Cheaper too....

Rebuild it, then you'll know what the floats are doin',...

It's a reasonably Easy carb to work on, 'n Edlebrock has a Great manual for it, at their website...

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Ayuh,.... Yer carb is a carbon copy of the Edlebrock Performer carb,...

Parts are Much easier to find for the Edlebrock, than the Merc parts, 'n Cheaper too....

Rebuild it, then you'll know what the floats are doin',...

It's a reasonably Easy carb to work on, 'n Edlebrock has a Great manual for it, at their website...

Edelbrock would bolt onto my existing intake manifold? I will check the website out. Thanks

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

the 1409 is identical to my Carter/Weber, except that my Carter has a manifold choke and the Edelbrock is electric. Don't know but I can't think it would be that big of a deal to convert.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

the 1409 is identical to my Carter/Weber, except that my Carter has a manifold choke and the Edelbrock is electric. Don't know but I can't think it would be that big of a deal to convert.

Finally got a chance to run the boat on the muffs today after changing the fuel / water sep filter. Ran it from 2200 - 2600 rpm on the muffs for about 15 minutes, periodically spiking the throttle trying to make it cough, quit or starve for fuel. Ran it without the flame arrestor so i could see that the front 2 bbls were getting fuel. that should make it run a touch leaner than normal. Never got a single cough, burp or sputter the whole time. My old fuel/water sep filter was three plus years old so I am assuming I waited too long to replace. I will be carrying a spare in the tool box now.

 

[Bondo]

Re: 1995 mercruiser 4.3 starving for fuel

Finally got a chance to run the boat on the muffs today after changing the fuel / water sep filter. Ran it from 2200 - 2600 rpm on the muffs for about 15 minutes, periodically spiking the throttle trying to make it cough, quit or starve for fuel. Ran it without the flame arrestor so i could see that the front 2 bbls were getting fuel. that should make it run a touch leaner than normal. Never got a single cough, burp or sputter the whole time. My old fuel/water sep filter was three plus years old so I am assuming I waited too long to replace. I will be carrying a spare in the tool box now.

Ayuh,.... Did ya inspect it's contents....

Yer muffs Test is a waste of time,....
Without a Load, that motor can't really burn any fuel,... even at 3000 rpms....

Ya gotta splash it to see if yer Fixed, or not....

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Ayuh,.... Did ya inspect it's contents....

Yer muffs Test is a waste of time,....
Without a Load, that motor can't really burn any fuel,... even at 3000 rpms....

Ya gotta splash it to see if yer Fixed, or not....

Probably drop her in this week some night to see how/if it runs.
I limped back to the ramp not able to run much over idle, 600 - 700 RPMS so I was happy with the results of the test on the muffs.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Bond-o,
FedEx is delivering my new Edelbrock 1409 this afternoon. Couldn't resist when I saw the price. Can't wait to get it installed and see how/if it runs. It has to be an improvement over my worn out Carter-Weber.

 

[Bondo]

Re: 1995 mercruiser 4.3 starving for fuel

Bond-o,
FedEx is delivering my new Edelbrock 1409 this afternoon. Couldn't resist when I saw the price. Can't wait to get it installed and see how/if it runs. It has to be an improvement over my worn out Carter-Weber.

Ayuh,... Good Luck...

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Finally had a chance to drop the boat in the river and give it a try. Started and ran great with the new Edelbrock 1409 carb... for the first 40 minutes... Then it wouldn't run above 2000 rpm. I have changed the fuel/water sep filter. I checked the vent line and it seems to be okay. I blew into the pickup line without the anti-siphon valve and it was free and clear. The anti-siphon valve seems very restricted for some reason. I will probably try a new one.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Finally had a chance to put the boat back in the river. Removed the old anti-siphon valve and replaced with a plain nipple (test purposes only). Ran the boat for about 2 hours with no problems. Was a little hard to start a few times but I think that was from the gas draining back into the tank. I'll be ordering a new anti-siphon valve.

 

[sharkin95]

Re: 1995 mercruiser 4.3 starving for fuel

So that $10.00 siphon valve on your gas tank costs you $375.00 for a new carb that you didn't need. when it's fuel work backwards bad gas,fuel tank,fuel lines,plugged 5/8" vent lines,anti syphon, fuel filter, elec pump, carburetor is the last thing.

 

[sjm32157]

Re: 1995 mercruiser 4.3 starving for fuel

Looking backward, you are probably right. The previous owner of the boat did his own carb work so there were a lot of screws changed out, cover for the one accelerator pump was home made, choke didn't work correctly, etc. So I didn't mind spending the cash for the new carb, and now that I am getting fuel, the boat runs better than it did with the Carter-Weber.