Problems with first rebuild

[nothingspecial]

Re: Problems with first rebuild

Ahoy everyone, Thanks for all the good advise. Wow!-there is a lot of water drained from all plugs and hoses. That could have been costly. Well I had a nice day (25 degrees) so I wanted to adjust timing to 10 degrees past tdc. I did that but still had a lot of trouble with carb? I am still getting fuel out the exhaust with water. Even with new mechanical fuel pump. It wont stay running unless choke is about a quarter open. Wide open choke on warm motor kills it. I contacted the seller and they think it is a vacuum issue. I sent it back and will get a new one with an electric choke. I hope this is the "fix-all" solution.

 

[FreeBeeTony]

Re: Problems with first rebuild

I wanted to adjust timing to 10 degrees past tdc. I did that but still had a lot of trouble with carb? QUOTE]

Timing should be Before TDC.......not sure what you mean by Past TDC.........
If the timing is retarded and not advanced it could be causing your idle issue.......

 

[NHGuy]

Re: Problems with first rebuild

You want your timing 8 degrees BTDC. And if it needs choke to run you probably have an air leak, which I wrote about diagnosing earlier.

Merry Christmas!

 

[nothingspecial]

Re: Problems with first rebuild

Happy New Year Everyone, Well I received my replacement carb this week. It looks like a new unit manufactured by Carter to replace the Rochester Quadrajet. It came with a very thick gasket (1/4 inch) that I installed with no rtv sealant. Should I use some sealant for this job? It has an electric choke and some kind of adjustment screw for choke/vacuum setting???? I have no idea what it does or how to set it. I started up the motor without making any adjustments to the carb. I set idle screw high- about 900-1000 rpm just to keep it running so I could set timing back to 8 btdc. I had hoped to put new carb on and it would be perfect-correct all old problems no such luck. The first time I started it ,I only had fuel coming out one side of the exhaust manifold. Thats 50% better than before. However, I now have backfire coming out of that same side (1,3,5,7) I am assuming this "rough" running is from the valve adjustment I did. Could an improper valve setting cause the back firing and fuel run out of exhaust? I took a 38 second video with my phone of her running to aide in problem solving. I did not have the back firing before I did valve adjustment. I tried messing with the two carb set screws to get it to idle around 650 rpm's but the severe backfiring scared me off. Thanks in advance.

Video-IMG_1696_zps3d331099.mp4 Video by nerissa461985 | Photobucket

 

[wrench 3]

Re: Problems with first rebuild

First thing to check when you have backfiring when not under load is the firing order. Then the valve adjustment.
The only vacuum adjustment for the choke that comes to mind is the choke brake. It opens the choke enough for the engine to run after it starts. It's a mechanical adjustment that can be done on the bench, so it should have been set to factory specs when you received it. And no sealer on the gasket.
BTW most marine carburetors do not have a fast idle, so you have to apply throttle to keep them running when cold.

 

[nothingspecial]

Re: Problems with first rebuild

Ahoy! Can anyone confirm that an improper valve adjustment could cause fuel to run out exhaust manifold? There is more fuel coming out of one side than the other. View video 2 threads up to see how much. Thank you.

 

[998cc]

Re: Problems with first rebuild

Have you checked the firing order as suggested by wrench 3? It appears to either be firing order or a valve not closing. Have you done a compression test after re-setting the valves? Also, is the fuel only coming out of that one side or both?
998cc

 

[Walt T]

Re: Problems with first rebuild

Fuel coming out is not valve adjustment. It is WAY too much gas getting dumped into the engine. Float level is probably way off and fuel is pouring in.

 

[wrench 3]

Re: Problems with first rebuild

There's definitely something strange going on here. New carburetter, new fuel pump, and still dumping fuel like crazy.
Could you post pictures of all the fuel and any vacuum lines on the engine.
BTW, this would not cause the backfiring.

 

[dingdongs]

Re: Problems with first rebuild


have you rechecked your firing order as some wires may be mixed up and not burning the fuel but exhausting it.

 

[NHGuy]

Re: Problems with first rebuild

Ahoy to you! If it's a Quadrajet by Carter they are qjet clones.
What you do after checking the wires is on the very front of the carb at the base are two adjusters. You might have to get a carb adjuster tool like this to turn them.

What you do is before the next start go through and snug all the intake manifold bolts, just in case there's a vacuum leak there. Then to do the prestart adjustment on the carb you GENTLY seat the mix adjusters on the bottom front of the carb and then back them out about 2.5 turns. Set the idle screw just against the stop plus maybe 1/8 turn.
Read this attachment. Print it out and take it to the boat, makes it easier.
Then attach some cooling water, fire it up, let it warm and set it!

 

[CharlieB]

Re: Problems with first rebuild

I haven't gone back to re-read the whole thread so I dno't remember if you have mentioned how old the spark plug wires are. It is critical that all cyls have a good plug wire for the spark voltage to be delivered to each plug. You may test spark one cyl at a time using an adjustable spark gap tester set to at least 1/4 inch. You need a nice hot blue arc, if not there on all cyls then replace the wires.

The tool and instruction from NHGuy are very important, follow it to the letter.

 

[funk6294]

Re: Problems with first rebuild

If you have fouled the plugs by running them too rich too long then you might want to swap those out. As for the backfire, check the firing order, also when you set the base timing with the est distributor I believe there is a jumper that has to be flipped to keep any advance from coming in and then flipped back after the base timing is set. Moving on to the carb... If fuel is still coming out of one of the boosters then you need to look at the float setting (make sure when the needle was put on the float they did not loop it through the retainer hole on the float). If the float height is good and the needle looks good then the only other place to look would be for excess fuel pressure.