Engine Hard Starting 304

[TrackRat]

Recently picked up a '76 CJ5 with the 304 from a friend. There had been a noticeable stumble when trying to get the vehicle rolling - took a bunch more throttle than it should have. Have since installed a new 500 CFM Holley with electric choke, new fuel filter, plugs, wires, replaced malfunctioning vacuum advance, and timed the jeep. Vehicle runs much better although still feels like there is a little hesitation upon initial acceleration - noticeable when manually applying throttle at the carb while idling.

Biggest problem I am having is that the thing really doesn't want to start in the mornings (live in Northern CA - been pretty mild / warm in the evenings as of late). Cranks fine. Have to stab the throttle quite a bit to get it to catch but will die right after. Keeping my foot in the throttle will cause it to catch but will barely get going, need to maintain steady throttle and higher RPM for a couple of minutes before I can let it idle on its own. Once warmed seems to run well.

Any suggestions? Vehicle runs an electric fuel pump in the engine bay of unknown history. I need to crawl back under again and double check but feel like I saw what I would have thought would have been an inline pump further back on the frame rail (not 100% there).

 

[TSB8C]

Usually hard starting resolved by "stabbing the throttle" as you stated, then runs fine after warm up, is a mixture issue. So either carb settings, choke, or fuel pressure are where to look. If there are two fuel pumps (electric in the engine bay and your suspected possible in-line on the frame rail), check that for sure. No reason to have two electric pumps for a standard 304 with a 500 cfm carb. So verify that and if you have a gauge, check the pressure at the carb inlet. You said you have an electric choke with the carb, how's the adjustment on that as well? Since you say it runs well after it's warmed up, I wouldn't suspect carb adjustments as much. Mixture settings and/or jetting is less likely if it runs fine once warmed up.

Of course the real answer - EFI. Love mine. Cold start, warm start, even remote start.

 

[rcazparts]

Recently picked up a '76 CJ5 with the 304 from a friend. There had been a noticeable stumble when trying to get the vehicle rolling - took a bunch more throttle than it should have. Have since installed a new 500 CFM Holley with electric choke, new fuel filter, plugs, wires, replaced malfunctioning vacuum advance, and timed the jeep. Vehicle runs much better although still feels like there is a little hesitation upon initial acceleration - noticeable when manually applying throttle at the carb while idling.

Biggest problem I am having is that the thing really doesn't want to start in the mornings (live in Northern CA - been pretty mild / warm in the evenings as of late). Cranks fine. Have to stab the throttle quite a bit to get it to catch but will die right after. Keeping my foot in the throttle will cause it to catch but will barely get going, need to maintain steady throttle and higher RPM for a couple of minutes before I can let it idle on its own. Once warmed seems to run well.

Any suggestions? Vehicle runs an electric fuel pump in the engine bay of unknown history. I need to crawl back under again and double check but feel like I saw what I would have thought would have been an inline pump further back on the frame rail (not 100% there).

New Holley's are usually pretty good out of the box. I would check choke adjustment. Engine cold, the blades should be closed. Make sure you wired it correctly: ground and a key on hot. The hot wire will slowly open the blades. Make sure they open fully and stay open. There are plenty of internet instructions on how to set it properly.

You should also check idle air mixture. This will drastically affect how it idles. You don't list model of carb. Most Holleys have an adjustment screw on each side of the carb. This screw is in the jet plate. Image below is taken from this holley.com link. Read the link, it describes better than I can here in this post.

Here Is The Correct Procedure For Setting An Optimized Idle Mixture And Speed

Setting the idle mixture and speed on a carburetor isn't the most exciting or elegant subject, but it is a necessary adjustment that often is overlooked or worse, set up incorrectly. Here's the proper way to handle this basic task.

www.holley.com