Gas dripping out of carbs

[seattle scott]

I have a 1977 Chrysler 135, HG model, twin carbs and twin fuel pumps. History of engine unknow except probably sat for a few years before I bought unrunning. Wasn't getting gas past the fuel pumps with the primer bulb ( dry float bowels). Rebult both fuel pumps and can get gas coming out of both carbs with primer bulb. Engine idles but gas drips out of both carbs, at more than a drop a second. Manual tells me to look at float levels or excessive fuel pump pressure. But I see other posters talking about needle valve seating. Does the fact of both carbs having same problem help in the diagnosis? Manual says that to adjust the floats I need to remove carbs and invert the float to start the adjustment. Should I start there? The inlet needle Part F016697 in no longer available, but the main nozzle part F016133 is avilable.

 

[RogersJetboat454]

Re: Gas dripping out of carbs

I have a 1977 Chrysler 135, HG model, twin carbs and twin fuel pumps. History of engine unknow except probably sat for a few years before I bought unrunning. Wasn't getting gas past the fuel pumps with the primer bulb ( dry float bowels). Rebult both fuel pumps and can get gas coming out of both carbs with primer bulb. Engine idles but gas drips out of both carbs, at more than a drop a second. Manual tells me to look at float levels or excessive fuel pump pressure. But I see other posters talking about needle valve seating. Does the fact of both carbs having same problem help in the diagnosis? Manual says that to adjust the floats I need to remove carbs and invert the float to start the adjustment. Should I start there? The inlet needle Part F016697 in no longer available, but the main nozzle part F016133 is avilable.

Scott,
Sounds like the manual assumes the carburetors are free of varnish and trash. If the busted fuel pumps were any indication of the neglected fuel system, chances are high there is probably junk in the carburetors.

Junk between the needle and seat assembles would prevent the carburetors from fully closing off the fuel source when the bowl is full, thus the carbs start puking the excessive fuel out.

Bare minimum the bowls should be pulled off the carbs, and the needles and seats + the inlets from the pumps should be cleaned out. If it were mine, I would do a full tear down and rebuild to be sure all the passages of the carbs are clean, so you don't run the engine lean. You should also consider replacing the supply lines to the carbs if they haven't already been done, because chances are old lines on this engine would not be happy with E10 fuel, and may have already started breaking down due to age anyway.

Just my 2?...

 

[seattle scott]

Re: Gas dripping out of carbs

Thanks Rogers. I will see what I can do/clean after removing the bowls. Carbs scare me with all the little parts etc.

the other thing is that the pumps are plummed such that upper pump feeds upper carb and lower pump feeds lower carb. The book doesn't tell me how to run the gas lines. Do I keep the pumps separate or buddy them up?

 

[Frank Acampora]

Re: Gas dripping out of carbs

Believe it or not, that engine can run on one pump feeding both carbs but the manual says you may experience reduced performance.


However, as you have it now, it is dangerous. If one pump should weaken or fail, the other will continue to feed two cylinders and more than likely you will suffer engine damage on at least one of the two cylinders serviced by the weak pump.

Correct way to plumb them is: Fuel feed from tank to bottom pump--black plastic inlet. Bottom pump outlet to top pump inlet --again, black plastic. Top pump outlet to carbs.

Now, I put a cheap inline filter between the pumps and carbs. To reduce resistance, I remove the screens from both inlets.

Unfortuately, this photo doesn't show the pumps, but it does show how I pipe the filter and carbs. You can, however, see the fuel line from the top pump to the carbs. If you look closely, you can also see on the inside of it the fuel line from the bottom pump to the top one. I happen to like that particular filter. It costs around 7 bucks and I get it at Pep Boy's auto store -- Purolator F50153

Needles and seats may no longer be available but they are the same parts (press in seats) used in TC carbs up until Merc discontinued Force engines in 1999.

 

[Frank Acampora]

Re: Gas dripping out of carbs



Here are a couple of photos of the correct fuel line and pulse line routing

 

[seattle scott]

Re: Gas dripping out of carbs

Frank, do I see a tee downstream from the filter with the lines after the tee basically verticle (straight up to the upper carb and straight down to the lower carb)?

Other than that, I understand the routing and the reasoning behind it on the fuel lines. Damn I just bought new pump inlet screens. Should I hold off on removal, meaning wait until I run the engine on the boat a while to see how it goes?

thanks

 

[~Nickolas~]

Re: Gas dripping out of carbs

Thats interesting I have the same exact motor and it only has one fuel pump. Now the 140 motors I have seen all have two fuel pumps but the 135 only one. I haven't seen that many of either really as out in the water 90 % of motors I see are newer Mercury's. I would do as other's suggest and take them apart and clean them real good, blow them out with air as in the passages and you should be fine. Carb inverted the float should be level.

 

[Frank Acampora]

Re: Gas dripping out of carbs

Yes, that's a tee. 3/8 or 5/16, whatever was handy at the time-- I forget which size I used. The tee makes it easier to insert the filter which has a 90 degree outlet.

I ran mine with screens for a while and there was no problem. However, they seem triple redundant when I also have a filter after the pumps. Filter has about the same size screen inside it.

 

[seattle scott]

Re: Gas dripping out of carbs

Thanks Frank. Will get to it this weekend.