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tbart16 06-13-2013 06:56 AM

tough starting CJ
i just picked up another 85 cj 4.2 4spd Hei and a weber carb. Problem I have if it sets over night it is a bugger to start the next day it seems like the fuel is leaking back into the tank. once started it runs and idles good there is a little flat spot inthe carb when pulling out but otherwise it runs well.

Yesterday evening I went out to try and start this thing and pumped and cranked for 15 seconds ,no spitting to sputtering just the engine turning over. So I give it a shot of starting fluid just to test my no gas theory. After a shot of starting fluid it fires up then dies so I crank for about 10 more seconds while puming the accelerator finally it spits and sputters to life.

Give me some input here thanks guys

iluvcowjuice 06-13-2013 08:35 AM

Sounds like a dying fuel pump

tbart16 06-13-2013 09:25 AM

is there a check valve or anti syphon built into the fuel pump??

LumpyGrits 06-13-2013 09:37 AM

Change the fuel filter and test the FP psi.
I had this issue till I went to a 3/8" 'feed' line from the 5/16"
Now my Carter carb'd '85 starts up real quick even if it has sat for a month or more.

tbart16 06-13-2013 09:50 AM

great advice and easily done thanks !

LumpyGrits 06-13-2013 09:56 AM

You may want to look into a ele. FP also.:thumbsup:

bkeese 06-13-2013 10:04 AM

Make sure the return line on your filter is on top, if not the gas will syphon back into the tank. Now that was real easy!!!

LumpyGrits 06-13-2013 10:16 AM

YUP :thumbsup:
Good point:tea:

tbart16 06-13-2013 11:18 AM

more great advice:D

tbart16 06-13-2013 08:59 PM

The return line is pointing towards the Carb or away from the pump. I am assuming the return line side is the side with 2 lines coming off of it. The pump and filter both look as though they have seen better days, I am probably going to replace the filter and pump regardless

BagusJeep 06-13-2013 09:03 PM

There are a number of areas you can check:

Fuel filter: It sounds lik you have the Jeep 3 way filter. Is it mounted horizontally near the carb and have the fuel return line at 12 o'clock? If so you will have an ounce of fuel sitting there. If you look at the original set up the fuel TUBE after the filter described a U bend before joining on to the carb, this would have held some fuel. You have probbaly lost this so try and get the filter higher so it is at least at the level of the inlet.

How are you starting it? Two dabs on the accelerator before turning the key?

They are swines to start if you have even a small vacuum leak. The Weber carb is designed at idle to completely close the throttle butterflies and direct all air through the air/fuel mixing tubes and idle jets, even a small vaccuum leak will lean out the idle mix, let alone if your choke device is not working. I have found replacing all the old cracked worn or loose vacuum tubes to be a great help in starting.

The mechanical fuel pump is reliable and I would not use an electric one on a stock 258, it is just another part to go wrong. The only time they fail is when the diaphragm gives up and it leaks, hopefully through the small hole underneath.

The filter can get blocked and is an annual service item.

Lastly, have a look at the choke mechanism, make sure it is operating.

I have the manual choke version of the Weber 38 but with the above all done it starts within 1.5 seconds on Bagusjeep and Puthijeep even after sitting for a month. It is such a vast improvement over the previous churning on the BBD taht I wonder why I resisted for so long having Webers.

tbart16 06-14-2013 06:40 AM

I do have the 3 way filter. it honestly takes almost a real minute of pumping the throttle to get it to start my other 85 with the Carter on it starts after 2-3 pumps 10-15 seconds. I will go through my Vac lines and try to recreate the u bend I was given a ton of paperwork about the carb when I bought the jeep so I do have some info to start with and all of the great advice from this forum also helps. I am still going to replace the filter and pump just as a preventive measure. thanks again guys

sanctified 06-14-2013 10:13 AM

When I dropped my gas tank I found that my roll over check valve (name?) and one other check valve was missing from the back end. I have the same issue that the OP describes where if it sits over night it takes some cranking before it will start. Once its going though it will start right up w/o any issues. Could those missing pieces be attributing to my start issue? I need to check the suggestions above as well.

sanctified 06-14-2013 10:37 AM


Originally Posted by bkeese (Post 15556384)
Make sure the return line on your filter is on top, if not the gas will syphon back into the tank. Now that was real easy!!!

Are you saying that on the three nipple filter the filter needs to be rotated so that the return nipple is sitting above the others? Right now my filter is flat ish and the nipples are all level on the same plane. I'm just trying to understand this better so I can adjust it if needed. I'm going to replace the filter this afternoon.

** Also, which hose is the return line?**

LumpyGrits 06-14-2013 10:41 AM

YES, return line on top.
The fuel filter fitting on the outside is the return.........

The time now is 02:03 AM.

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