Engine starts ok, but immediately shuts off:

[fussfeld]

As you might know i'm almost done with a 305 to 4.3 swap.


What's happening now is that the engine will start, but it immediately shuts off after you release the key from the start position

The only thing i did was to bypass the ESC function on the distributor (All carbed 4.3's in trucks got the ESC distributor) by connecting the black and green wires on the pigtail that normally plugs into the esc computer.


Thoughts?

 

[87ChevyR10]

I got a thought... Check here: http://www.gmsquarebody.com/forum/showthread.php?t=13470

Oh wait! That's your other thread of the exact same topic! DOH!

 

[chengny]

Here are a couple of things to check/try:

1. Key in the RUN position, confirm 12 VDC on the pink lead that connects to the BAT terminal.

2. Next, while cranking the starter, use a meter or test lamp to confirm 12 VDC (or so)

3. Then check whether that voltage drops off (like below 10) when the ignition key - or remote starter button if that is what you're using - is released

4. If it does drop below 10 VDC, try running a hot wire - from the battery positive directly to the BAT terminal on the distributor.

If it fires - and stays running - with a direct battery feed, suspect a bad ignition switch


If you still don't get a consistent, healthy spark, take it one step further: provide a 12 VDC supply to the coil primary from a completely external source (e.g. a battery charger, another vehicle or just a spare battery).

Note the results of that test and report back.

 

[fussfeld]

Ok, i got it solved (i think/hope?)----there wasn't enough fuel in the bowl. So this time, i am filled it up all the way thru the vent hole.

It ran much longer this time. It did cut out after say 3-5 secs but i think this is due to the fact that this is the first time it has really run since oct 13.

 

[fussfeld]

Here are a couple of things to check/try:

1. Key in the RUN position, confirm 12 VDC on the pink lead that connects to the BAT terminal.

2. Next, while cranking the starter, use a meter or test lamp to confirm 12 VDC (or so)

3. Then check whether that voltage drops off (like below 10) when the ignition key - or remote starter button if that is what you're using - is released

4. If it does drop below 10 VDC, try running a hot wire - from the battery positive directly to the BAT terminal on the distributor.

If it fires - and stays running - with a direct battery feed, suspect a bad ignition switch


If you still don't get a consistent, healthy spark, take it one step further: provide a 12 VDC supply to the coil primary from a completely external source (e.g. a battery charger, another vehicle or just a spare battery).

Note the results of that test and report back.

Thanks for the help----hopefully the lack of fuel was the problem.

 

[chengny]

Are you frickin' kidding me?

 

[fussfeld]

No, i don't think so?