b7labelle

Hi Everyone,

I'm hoping someone on here has had experience with the problem I am facing currently with my 87 318 2bbl. Any suggestions would be appreciated!

Little background story...

Drove the truck for 2 years as my daily drivers. Had to park it for 2 years. Recently got it running again (new battery), and have driven it occasionally on the weekends around town. One morning after taking it off the high idle, the engine starts to slowly loose RPM and struggles to stay running. Sometimes it does slowly come to a stall. Stalling behavior happens repeatably now when I put it in D or R and don't apply throttle, when on the low idle. If apply throttle this will stop the stall and the idle speed rises.

After doing some more reading I checked out the choke this morning...closed when cold, opens as engine warms. Issue only occurs when on the low idle and engine load is light. Stop and go traffic is terrible.

Tried spraying out the carb with some carb cleaner, does not appear to have made a difference. Last winter I replaced the mechanical fuel pump. Only vacuum noise I hear I believe is coming from the carb intake itself. Will probably pick up a fuel filter today.

Again the issue is only when engine load is light, drives fine on highway. Issue does not occur when in N or P.

-b7

bremereric

Vacuum leak or crap in the carb. Either way put a vacuum gage on it and notice the drop you get when you put it into gear. You should not drop more than 200 rpms.

TVLynn

Plugged idle jets ?? Try running some fuel system cleaner in the gas

moe7404

fire your air compreser up. count what the idle mix screws are set at. take one out blow air into the mix hole. then do the other one . put the mix screws back in. and see if it is better.

b7labelle

Hi TV and Moe,
Thanks for the suggestions. Another note that I wanted to add is that it does not act up immediately on low idle...I took it down the drive after it warmed up and let it idle in drive without any issues. Went back down the drive and back again, and when I stopped the idle issue returned. This is what makes me unsure about having clogged idle jets.

ALSO....when I first fired up the truck to check the timing, I couldn't even see the timing notch on the crank pulley. When I kicked it off high idle, the timing notch suddenly appeared at about 2* BTDC. I adjusted this back to about 7-8* BDTC.

This behavior confuses me...when is the timing moving like that? That does not sound normal, unless there is some sort of vacuum advance system that is supposed to do that. When I restarted the truck later, the timing notch was still at about the 7-8* BTDC. I took it for the above mentioned spin down the drive and all went well until I returned. When I came to a stop the issue resumed...I tried to re-hook up the timing light I purchased from Harbor Freight, and go figure, the tool no longer worked (Or i have a bigger issue on my hands). Good thing I kept my receipt.

So I think tomorrow I will return the timing light and pick up a nicer one else where, and replace the plugs/wires, as they are going on 3 years old.


Moe,
Do you know where the idle mixture screws are located on these 2bbl carbs?


-B7

moe7404

on a 87 318 the mix screws they may be hidden in side a casting at the bottom facing forward. on some you have to cut the casting off. i was still stuck in the past. and the idle jet tube in side the carb is set quite lean. it can be drilled out BUT it is not for every one to do. these things make this carb harder to set right. about all you can do is clean it as best you can.